CONSERVATION TECHNOLOGY

5 DRONES FOR CONSERVATION

5 DRONES FOR CONSERVATIONCONSERVATION TECHNOLOGY

Drone technologies
for conservation
James Duffy1, Karen Anderson1, Aurélie Shapiro2, Felipe Spina Avino3, Leon
DeBell1, Paul Glover-Kapfer4. 2020. WWF Conservation Technology Series 1(5).

WWF is one of the world’s largest and most experienced independent conservation organizations, withover 5 million supporters and a global network active in more than 100 countries. WWF’s mission is tostop the degradation of the planet’s natural environment and to build a future in which humans live inharmony with nature by conserving the world’s biological diversity, ensuring that the use of renewable
natural resources is sustainable, and promoting the reduction of pollution and wasteful consumption.

Author Affiliations:
1 - University of Exeter Drone Lab
2 - Space+Science, WWF-Germany
3 - WWF-Brazil
4 - Flora & Fauna International

Cover image: Kandahalagala Island in the Huvadhu Atoll, The Maldives. Photo captured with a Ricoh GRII
mounted on a 3DR Solo © James Duffy
Report designed by Anita Drbohlav (www.paneemadesign.com), editorial support Espin Bowder
Recommended Citation:
Duffy, J.P., Anderson, K., Shapiro, A.C., Spina Avino, F. L. DeBell & Glover-Kapfer, P. 2020.
Drone Technologies for Conservation. WWF Conservation Technology Series 1(5). WWF.
© WWF

Aerial view of rice cultivation, Ubud, Bali, Indonesia.
© Fabia Gysel/iStock/Getty Images

DRONES FOR CONSERVATION

4FIGURESCHAPTER 2
Figure 1

A timeline of military and civilian uses for drones –from Giomes and Brem (2017)	

20

Zipline uses drone technology to deliver urgent medical
supplies to local communities

21

Figure 3	A drone image showing dryland vegetation in the New Mexico Desert,
taken by a DJI Phantom 4

28

Figure 4	Orangutan nest spotted during aerial drone survey in
Bukit Puton Forest Reserve	30

Figure 5

Fishing boats offloading their catches in Kayar, Senegal	

31

Figure 6

Drone-based survey of Amazon river dolphins, Brazil	

32

Figure 7

Using drones to estimate body characteristics of cetaceans	

34

Figure 2

CHAPTER 3

Figure 8	Seven points of good practice for drone operations– adapted from Hodgson and Koh (2016)	

35

Figure 9	Training Indigenous groups in the Amazon forest to monitor
forest fires and deforestation with the help of drones	37

CHAPTER 5
Figure 10	Commercial multi-rotor drones make up most of the accessible
consumer drone market	

41

Figure 11	Custom-built fixed wing drone. X-UAV Skua frame with 3DR
Pixhawk autopilot, uBlox M8N GNSS, Purple Power PO-3548-1100
Professional Brushless Motor, 10x6 wooden propeller, 60A t-motor
ESC, FrSky digital metal servos and 10000mAh battery

44

Figure 12

Commercial fixed-wing eBee survey drone	

45

Figure 13

Calculating the landing area for fixed wing drones	

45

Figure 14

Amazon prototype Prime Air Drone	

45

Figure 15

A low-cost fixed wing system used by “Conservation Drones”	46

Figure 16

Depiction of wind dihedral and impact on flight stability	

47

Figure 17

Parachute landing capability for a fixed wing drone	47

5

DRONES FOR CONSERVATION

Figure 18	Commercial drones: left is the 3DR Solo and right is the Phantom 4.
Both include gimballed cameras, weigh <2kg take-off weight andcan fly for 15–25 minutes on a single battery (<1500€).	

48

Figure 19	Modified Tarot 650 frame quadcopter with 3DR pixhawk autopilot,
multistar motor and propellors, ublox M8N GNSS and 1000mAhbattery	

49

Figure 20	Assembling low cost multi-rotor drones using Pixhawk in
the Brazilian Cerrado	

50

Figure 21	A 3DR Solo drone is outfitted with several cameras and extra batteries,
which are checked before every flight	53
Figure 22	This custom-built drone has 6 rotors to carry an SLR camera for professional photography	
54
Figure 23

Ortho-mosaic and DSM over an illegally burned forest in a
Brazilian Amazon protected area	

58

CHAPTER 7
Figure 24	Example DROTAM map for the south-west United States on
September 9, 2020. DROTAMS in red and purple are restricted
UAV airspace, due to military or other planned activities. Circle
contain information denoting other airspace restriction to certain
heights above ground level

70

Figure 25	The complex volumetry “airspace” designations that broadly apply
globally	

70

Figure 26	Drone recommendations from the civil aviation authorityof Singapore	

72

Figure 27	Left: Screenshot from the NATS-Assist app on 20 December 2018.
The blue dot shows the drone operator’s location, and the coloured
circular areas are those places where airspace restrictions exist.
Using this app, users can raise NOTAMs for drone operations.
Right: Screenshots from the B4UFLY app/	73

Figure 28	The use of a ground-based RTK survey system includes abase station (left) and ground control points reference markers
deployed within the survey area (right).	

75

Figure 29 	A drone-based survey of gharials in Nepal, a critically endangered
crocodile species known for their significant length	81

CHAPTER 8

Chapter 9
Figure 30

 raining Indigenous groups in the Amazon forest to monitor fires andT
deforestation with the help of drones	88DRONES FOR CONSERVATION

6CHAPTER 10
Figure 31	Humpback whales, honorable mention Wildlife category, 2018 Drone
Awards	

94

Figure 32

96

The Skyrunner is a polish UAV Blimp made by sky&you 	

CHAPTER 11
Figure 33	A visible RGB drone image (top) and the thermal vision appraoch fordetecting hidden fawns in spring meadows. The fawns are automaticallydetected by AI software and rescued before mowing operations	
99
Figure 34

Protective cage for DJI Mavic 2	100

Figure 35

Drone swarm over the city wall of Xi’an	

102

Figure 36

Example of solar-powered wing drone	

104

Figure 37

Airspace classification and requirements for pilots	

106

Figure 38	Airspace management system that incoroporates lightweight drones

107

Figure 39

Unmanned Traffic Management System being explored by the FAA108

Table 1

Examples of lightweight drone systems used in ecological research

24

Table 2

Summary of different drone capabilities

60

Table 3	A summary of operational modes for most lightweightconsumer-grade drones

74

Table 4	UAV industry and legislation for the major economic regionsof the world.	76

Table 5

Available third-party drone planning software and apps

82

Table 6

A non-exhaustive list of photogrammetry software packages. 	

83

TABLES

7

DRONES FOR CONSERVATIONGLOSSARY OF TERMS
AGL
AOI
ARF
ATC
BEC
B-VLOS
CAA
CHDK
CMOS
CW
CCW
DSM
DJI
ESC
FL
FLIR
FPV
GIS
GPS
GNSS
IATA
ICAO
KAP
LiDAR
LiPo
LRS
MP
NATS
NDVI
NGO
NOTAM
OPTO
OSD
PfAW
PNP
PPK
RC
RGB
RPAS
RTF
RTH
RTK
RTL
SfM-MVS
TLS
TOW
UAV
UTM
VFR
VLOS

Above Ground Level
Area of Interest
Almost Ready to Fly
Air Traffic Control
Battery Eliminator Circuit
Beyond Visual Line of Site
Civil Aviation Authority
Canon Hack Development Kit
Complementary Metal-Oxide-Semiconductor
Clockwise
Counter-clockwise
Digital Surface Model
Da-Jiang Innovations
Electronic Speed Controller
Flight Level
Forward Looking Infrared Radar
First Person View
Geographical Information Systems
Global Positioning System
Global Navigation Satellite System
International Air Transport Association
International Civil Aviation Organisation
Kite Aerial Photography
Light Detection and Ranging
Lithium Polymer
Long Range Systems
Megapixels
National Air Traffic Services
Normalised Difference Vegetation Index
Non-governmental Organisation
Notice to Airmen (sic)Optoisolators
On-screen Display
Permission for Aerial Work
Plug and Play
Post Processing Kinematics
Radio Controlled
Red, Green, Blue
Remotely Piloted Aircraft System
Ready to Fly
Return to Home
Real Time Kinematics
Return to Launch
Structure-from-Motion Multi-View Stereo
Terrestrial Laser Scanner
Take-off Weight
Unmanned (sic) Aerial Vehicle
Unmanned (sic) Aircraft Systems Traffic Management
Visual Flight Rules
Visual Line of Sight

DRONES FOR CONSERVATION

8TABLE OF CONTENTS
1

2

Preface	

16

1.1
1.2
1.3

16
17
17

Introduction	
Scope	The structure of this guide	

Drone Evolution	

19

2.1
2.1
2.3

Military beginnings	The drone dichotomy in conservation	
Hobbyist platforms for science and conservation	

19
20
22

So, you want to use a drone for conservation?	

27

3.1
3.2
3.3
3.4
3.5
3.6
3.7

State-of-the-art drones in conservation	
Terrestrial flora	
Terrestrial fauna	
Marine/coastal flora	
Aquatic systems	
Human-drone-wildlife nexus	Protected Area management 	

27
27
30
31
32
36
36

4

Executing a drone survey in 10 clear steps	39

5

Drone Anatomy	

41

5.1
5.1.1
5.1.2
5.1.3
5.2
5.3
5.3.1
5.3.2
5.3.3
5.3.4
5.4
5.4.1
5.4.2
5.4.3
5.4.4

42
43
43
48
50
51
51
53
54
55
56
56
57
59
59

3

6

Aircraft types	Tethered balloons and kites	
Fixed Wing	Multi-rotor drones	Flight control	
Batteries	Safety of LiPos	
Charge, discharge and battery life	Travelling with LiPo batteries	Summary	Motors, propellers and electronic speed controllers	Motors	
Propellers	Electronic Speed Controllers (ESCs)	
Radio control (Rx/Tx) and telemetry	Drone sensors	

63

6.1
6.2

63
64

Introduction	
Overview of drone sensors	9DRONES FOR CONSERVATION

7

8Flight planning and operations	

69

7.1
7.2
7.3
7.4
7.5
7.6

69
69
74
75
76
77

Introduction	
Airspace	Flight modes	
Navigation and accuracy	Legal issues and permits	Best practice	Drone Data	

79

8.1
8.2
8.2.1
8.2.2
8.2.3
8.3

The drone’s niche	
Available software and costs	
Mission planning software
Ground station software	
Data processing and analysis software 	
Data processing approaches	

79
81
81
82
83
84

9

Highlights from WWF’s conservation activities	8710Technological limitations, caveats and solutions	

91

10.1
10.2
10.3
10.4

91
92
95
95

11

Platform Limitations 	Sensor Limitations	Legislative Limitations	
Alternative proximal sensing approaches	

Future trends and potentials	

99

11.1
First Person View (FPV) flying	
11.2
Caged drones	
11.3
Autonomous guidance	
11.4
Differential GPS PPK/RTK	
11.5
Swarms	
11.6
Autonomy in power and charging	
11.7
Upscaling, data assimilation, remote sensing workflow	
11.8	Legislative framework – better integration of drones into airspace	

99
100
100
101
102
104
105
106

12

Summary of Case Studies	

111

13

References	113

DRONES FOR CONSERVATION10DRONES FOR CONSERVATION FAQ
What is a drone? (Chapter 5)
In the context of conservation and science, drones are lightweight aircraft platforms which
can be purchased ‘ready to fly’ or be assembled & personalized by the user and equippedwith integrated sensors, such as cameras or laser scanners. Less frequently, the platform ispurchased with no integrated sensors, and adapted to carry sensors for different purposes,
e.g. thermal imaging for detecting nocturnal animals, or multispectral/hyperspectral
sensors for use in plant science applications. Drones come in all shapes and sizes andare manufactured by a wide range of suppliers. They are usually equipped with GPS andsophisticated autopilots and many models can be programmed to fly along ‘waypointed’(GPS-guided) routes for executing robust aerial surveys, much like a piloted survey aircraft
would do. The autopilots in most modern consumer drones allow the aircraft to be flown
by non-expert pilots, since they provide excellent control and stability of the aircraft inflight. Drones may be multi-rotor or fixed wing. The application and the geographic setting
for surveys dictates which type of platform is best for the job.
How are drone data collected?
The way that data are collected from drones varies from one application to another. Typically, a drone will be fitted with a sensor (a camera, a thermal imager or something moresophisticated such as a hyperspectral radiometer). The drone is then flown over the area ofinterest and the sensor captures data in flight. The data will usually be stored on a memory
card within the sensor, or on the drone itself, depending on whether or how the sensor is
integrated into the drone hardware. The way that the drone is flown and the type of sensor
on board will affect the quality and spatial resolution of the data captured. In many cases,
the sensor can be programmed to trigger an image capture at regular intervals during theflight (for stills) or as a video. The application will determine which of these trigger methods is most suitable. For survey applications, where a map or photogrammetry productis desired, the drone will often be flown in a ‘lawnmower’ pattern over the site of interest,
going back and forth to cover the required survey area. The pilot can programme this survey flight to have different levels of overlap, depending on the desired quality of the output.
For more bespoke applications, for example, sampling whale sputum onto a petri dish, or
filming animal behaviour, the pilot may need to fly the drone manually using visual control
either using line-of-sight operation or from the first-person-view camera on board. The
latter gives the pilot a real-time view of the position of the drone relative to the subject ofinterest and allows the drone to be positioned precisely through manual pilot control.
What can drone data be used for? (Chapter 3)This report details the wide variety of applications that scientists and conservationists
have already implemented with drones. Reading about these examples may give you ideas
about whether a drone is fit for your specific application. Broadly speaking, any application
where imaging data can answer questions (e.g. about the spatial pattern in landscapes or
temporal dynamics of an environmental phenomena) may be a suitable target for drone
research. In non-imaging studies, the drone is an agile device that can be used to manoeuvre all kinds of payloads into difficult positions. With some ingenuity and careful planning,a drone can perform sampling functions not possible with other equipment.

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DRONES FOR CONSERVATION

Can drone data be used without any post-processing?
The conversion of data to information usually requires some data ‘processing’ but thisdoes not always have to be computationally demanding. For example, an expert mightview the raw video output from a camera mounted on a drone and use this to record species/population counts. In this case, the data would require minimal processing, but thetime investment of the expert reviewing the video would be quite high. To produce photogrammetric products or to stitch together high quality orthomosaics requires detailed
image processing workflows, and demands a capable desktop PC, or an on-demand
cloud-based processing services. Processing of high quality radiometric multispectralor hyperspectral drone imaging products, or extracting information from drone-derived
laser scanning data, will further add to the processing demands and will likely require
bespoke software.
How are drone data processed? (chapter 8)
This depends on the data and the application. On a basic level, a single drone aerial
photography survey of 10-20 minutes, with the camera triggering every 2–3 seconds can
produce hundreds of geotagged photographs. On their own, each photograph may containuseful information, but the power of these data lies in combining the photographs to produce geographic layers (e.g. orthomosaics, GeoTIFFs, point clouds, digital surface models)that can be analysed rigorously using geospatial workflows. To generate such products
requires access to software that can perform this image stitching. There are open-source
options and commercial products for doing so, with varying levels of technical capability required to extract high quality outputs. Open-source tools can be more flexible inthis regard but often require a higher level understanding of scripting/coding languages(Forsmoo et al., 2019). To execute these workflows a decent desktop PC is needed as theprocessing demands grow with greater numbers of photographs - although there are new
options for processing becoming increasingly available for processing and storing big
data in the cloud. For videographic analysis, equally, there will be requirements for video
editing software and a good computer processor to allow the researcher to extract useful
information from the drone video capture. More specialised research sensors, and thermal
imagers will usually have their own software and workflows for extracting information.
How much area can a drone survey cover in a single flight? (Chapter 5)
The answer depends on various site-specific factors, data requirements and the platform
being used. Concerning the platform, fixed wing aircraft are typically more aerodynamic
than multi-rotor aircraft and have fewer motors to power, meaning less power required
to travel the same distance, under the same conditions. Fixed wing aircraft are therefore
more suitable for large surveys areas (>100 ha) because of their improved endurance.
Beyond visual line of sight surveys also typically use fixed wing aircraft for the same
reason, although these longer distance flights may require special permissions. Additionally, fixed wing aircraft are more prone to forces such as wind and therefore controllingthe speed of the platform can be challenging in ceratain weather conditions. Multi-rotor
aircraft on the other hand can achieve relative stability in position and constancy in
speed even in high wind situations, making the data from these more reproducible andless prone to errors caused by such factors (e.g. image smear or blur if the platform ismoving very fast or being buffered by wind). As a general rule the latest consumer grade
multirotor platforms from leading manufacturers offer endurance of 18–25 minutes per
battery (as of September 2020), which is considerably lower than the expected flight timeof a similar grade fixed wing system. It is ultimately the battery life which limits the sizeof area that can be surveyed in a single flight. Second, site specific factors might dictate

DRONES FOR CONSERVATION

12

more complex flight plans being used (e.g. complex topography), and such issues can
reduce endurance in the platform if the drone is having to ascend and descend regularly
during the survey.
Third, the data requirements are a key consideration. Photogrammetric workflows may
require high levels of image overlap between images, necessitating a denser networkof flight lines. This means that the capacity to cover a larger area is reduced, and thisbecomes more extreme at lower flight altitudes. It can be addressed by increasing theflying height (since overlap increases as the camera is raised higher) but at the cost of
reduced spatial resolution.
What spatial resolution can I expect from a drone survey?
This depends on flying height and the sensor being used. Expected ground sampling distance can be calculated with some simple equations. As a rule of thumb, drones fitted withhigh quality (>10 MP) cameras are expected to achieve around 1–2 cm spatial resolution
at a flying height of 20–50 m. Climbing to 100 m, the resolution may coarsen to 2–5 cm.
For more specialised sensors the spatial resolution capability will depend on the optics ofthe camera, and we advise users to consult specific user manuals since there can be considerable variability from sensor to sensor. Thermal cameras suitable for deployment ondrones currently deliver data at a spatial resolution that is around an order of magnitude
coarser than optical camera images (e.g. 1 cm RGB = 10 cm Thermal).
What are the ethical issues with drone surveys?
There are many ethical considerations that need to be considered before you take to theskies with your drone. The drone can be a democratic instrument in the right hands – itprovides humans with access to airspace that otherwise lies outside of our gravitational
capability. From this new viewpoint we can observe and measure things from a different perspective, but that perspective is a powerful one which should be used carefully
and with an open view of the ethical issues in mind. Flying drones around human andnon-human subjects can give rise to a range of emotional and physiological effects inyour subjects, many of which are poorly understood in the case of non-humans. We
discuss some of these considerations in section 3.6 and Figure 8 provides some bullet
points for consideration prior to flights. Due to the fact that drones are synonymous with‘flying cameras’ researchers must always consider issues around data protection andprivacy – for which there are stringent national and international laws. Photographing
people without their prior permission violates privacy laws in most countries. Flying overprivate property without obtaining permission is similarly problematic. Some people just
don’t like drones – this may be for unexplainable reasons, or it may be due to spiritual or
religious beliefs; the latter particularly applies to the case of indigenous communities in13

DRONES FOR CONSERVATION

some parts of the world (Sandbrook, 2015). We advise all researchers and conservationists to discuss and seek ethical approval for their operations from within their institutional structures.
What are the legal issues associated with drone surveys? (Chapter 7)

The online community
diydrones.com offer a
excellent forum for homebuilt drones and related
topics.

Similarly to ethics, legality of drone use is complex and varies spatially and temporally.
At the time of writing, national and international aviation authorities are grappling withdrone laws to decide how the aerial volume should be divided, and whether (and where)
drones fit within the management of future airspace. Presently, there are some general
guidelines that can offer some reassurance. Small drones with a total take-off-mass ofless than 7 kg, are relatively free to explore the near-surface airspace up to around 100 m
above ground level in most countries of the world, as long as these are in ‘uncongested’
zones free of other air traffic and away from densely populated areas. In doing so the pilot
in command must maintain visual line of sight to the aircraft and typically, this meansthat the aircraft cannot travel more than 500 m away from its pilot. There are exceptions
to this rule, most obviously in no-fly-zones around airports for example, where flying
a drone of any size or type is strictly forbidden, and could lead to arrest and a fine, atthe very least. The best course of action for any drone pilot would be to first check theaviation laws in the planned country of operation, ensuring first that there is no nationalban on drones. In some countries there are special areas where drones may only be flown
with a government permit (e.g. in the national park around mount Everest), and drone
pilots should therefore prepare well in advance of any fieldtrip to ensure that they havethe paperwork in place. There are nuanced rules globally about drone piloting and competence that we urge all pilots to be cautious and mindful of. For example, in the USA,drones can only be flown by pilots who have passed their Federal Aviation Authority Part
107 exam, and some national parks and state parks operate under drone bans. In many
countries across Europe a different model exists for ‘commercial operation’ compared to‘research operation’ of a drone. If you are being paid for the services you will deliver fromyour drone (e.g. aerial photography, or video capture) you will normally need to complete a government-approved course to register as a drone pilot, producing an operations
manual and proving that you are sufficiently insured before you can legally fly (Cunliffe etal., 2017). For all these reasons, preparation is key – read up on what’s allowed and what
paperwork you need before travelling, and before you take off.
How much does a survey drone cost?
Highly capable lightweight (<7 kg take off weight) ‘consumer’ grade drones manufactured by the major brands are now very suitable for performing geospatial surveys. These
can cost anywhere between €1,000 and €10,000 depending on capability and the sensors
fitted. The more expensive end of the range would include drones fitted with differential
GPS positioning (e.g. using RTK or PPK protocols to provide <2 cm spatial accuracy of
products) or multispectral sensors. At the lower end of this range, you could expect toget a highly sophisticated multirotor system with all the necessary failsafes included(e.g. obstacle avoidance) as well as capabilities such as ‘follow me’, and a gimballed highquality RGB camera. Lidar-equipped drones are considerably more expensive and heavier machines – you could expect to pay up to €100,000 for one of these, and to fly themwould require a special license in most countries owing to the size and take off weight ofthe drone (>20 kg in some cases). It is also possible to buy off-the-shelf ‘hobbyist’ drone
platforms with no integrated sensors for considerably less than €1000. These would
require a more ‘grassroots’ experimental approach (Anderson et al., 2016) and the user
would have to modify the airframe to hold a sensor/sensors. It is likely that if you wanted
to follow this route of ‘build your own’ you would need to take advice of radio-controlled

DRONES FOR CONSERVATION

14

aircraft experts. In this case, the online community diydrones.com provide excellent user
forums with extensive information on a whole variety of relevant topics. You would alsoneed access to basic electronics equipment to adjust wiring and add components(e.g. sensor triggers).
How are drone data different from other types of remote sensing data?
(Chapter 6)
The main differences are spatial resolution and coverage. Drone data typically coversmaller spatial extents (10–100 ha per survey, typically) but provide finer spatial resolution data than those captured by survey aircraft or satellites. Drone surveys can be flown
on demand providing a custom or finer temporal resolution than other remote sensing
data. Drone data provide a localised picture of environments and ecosystems which
can be useful for scaling up or validation experiments, or validating, calibrating coarser-grained satellite observations, for example. In many cases, drone data are useful on
their own for studying individual animals or plants within a specific setting.
Can drone data be used with other geospatial datasets?
As explained above, yes. Once the drone data have been processed to generate a series ofgeospatial data layers (e.g. orthomosaic, multispectral map, point cloud or digital surface
model) these layers can be imported into geospatial analysis software (e.g. GIS) and usedalongside any other datasets of your choosing. Accuracy considerations are critical here –the GPS on board the drone will only have the same accuracy as a normal handheld GPS(nominally +/- 10 m, and potentially worse in the vertical domain than horizontal). If you
wish to improve the spatial positioning of your drone data it is possible to do that using
ground control points (localized features on the ground, which are visible in imagery andgeo-positioned using high accuracy survey GPS) which constrain the bundle adjustment
during processing. This requires additional equipment and processing effort.
Besides a drone, what other pieces of equipment necessary for drone
surveys?
Survey drones equipped with cameras and in-built GPS have all you will need to generatebasic mapping products. However, if you need enhanced accuracy or a means of vali­
dating the quality of the data you collect, you may also want to consider including thefollowing in your field kit:
1.

Targets can be deployed in the field to provide ground control, for improving theaccuracy of the photogrammetric build (if applicable) and for validation. Usuallythese are 30 x 30 cm sprayed plastic targets, held in place with tent pegs. Ideally, you
should deploy between 5 and 15 of these across the site for robust results, although
this is debated in the literature (James et al., 2017a). Cunliffe and Anderson (2019)provide further details (see section 7.4).

2.

A high accuracy GPS which exceeds that of the on-board GPS on the drone. This canbe used to survey the ground control points to a higher spatial accuracy, and thearising data used to constrain the build within photogrammetric workflows.

3.

Calibration targets, which are coloured in different shades, to provide a variety ofsurface reflectances across the visible and near infra red range, will be necessary/
essential if using multispectral/hyperspectral fully radiometric sensors.

4.

Field notebooks are essential for recording the details of each flight (take off/landing

15

DRONES FOR CONSERVATION

times, illumination conditions, issues encountered, battery number and drain).
5.

A waterproof carry case is useful for sheltering the drone in case of unexpected
wet weather.

6.

Field spectroradiometers to measure the reflectance of objects in situ may berequired if also using multispectral/hyperspectral fully radiometric sensors

7.

Lens cleaning cloths are especially useful to ensure good image quality.

In specific field scenarios, there may be other pieces of kit you need. We recommend
referring to Duffy et al. (2017) for insights into methodological pitfalls of working inchallenging remote environments with drones, including various suggestions for extra
items of field kit for use in high latitude, high altitude, wet tropical or dry desert climates.

Drones were used to assess
the world’s largest green
turtle rookery on the
Great Barrier reef.
© Queensland Government

DRONES FOR CONSERVATION

16PREFACE
1.1

Introduction

The Anthropocene – the current epoch in which we live in – defines the current geological time period of rapid global change (Steffen et al., 2011, Dirzo et al., 2014). Alongside
the negative aspects of life in the Anthropocene (pollution, habitat loss and degradation,
extinction, and rapid climate change) parallel positive developments are occurring –technology is rapidly evolving, and there are vast and expanding frontiers for exploration and observation. In this age of rapid technological and global change, humans facemultifaceted challenges associated with managing and mitigating changes in climate,
population growth, over-exploitation of natural resources and their subsequent impacts.
Data (particularly spatial data) provide a crucially important underpinning to environmental decision-making for a sustainable future. As presented in previous issues of the
WWF Conservation Technologies and Methodologies Series (Melin et al., 2017, Wearn
and Glover-Kaepfer, 2017, Browning et al., 2017, Pettorelli et al., 2018a), remote sensing
data (spatial ‘imaging’ data and products delivered by sensors on board satellites or aircraft) can provide a means by which ecosystems can be mapped at multiple scales to allow
countermeasures to be planned and implemented at appropriate scales. Whilst data fromsatellites can provide a large-extent picture of contemporary change across continents
and oceans, the spatial resolution (i.e. grain, or pixel size) of such data, or the timingof data collection, or quality due to clouds or atmosphere may not meet the needs forsite-specific investigations. Many of the management issues relating to individual species
or sensitive habitat areas require data at a finer spatial and temporal resolution for which
sensors mounted on piloted airplanes can provide. However, such data can be expensive
to acquire, they burn fossil fuels and require access to a suitably equipped scientific-grade
aircraft, pilot and permissions, which may be out of reach for many researchers. Furthermore, survey flights over remote territories or unstable areas can be risky, placing conservationists and field staff at risk of injury and death.

Drones provide aself-service capability
so the timing, resolution
and extent of surveys
are entirely usercontrolled.

Drones, or remotely piloted aerial systems, have now emerged into the consumer market
and are of great utility for local-extent (1-100 ha per flight) surveys and observations,and are widely being used by researchers (Schiffman, 2014), following a long historyof military use for surveillance and warfare. Conservationists have rapidly adapted
consumer grade drone technology for ‘proximal’ sensing purposes and other applications(Sandbrook, 2015, Koh and Wich, 2012). At the time of writing, drone use is booming inconservation, with lightweight platforms being put to use in diverse fields, from sampling
whale blow (sputum) samples (Geoghegan et al., 2018) to acquisition of aerial data forvegetation surveys (Dandois and Ellis, 2010, Zahawi et al., 2015), animal monitoring(Pomeroy et al., 2015), anti-poaching operations (Massé, 2018), and underwater coral reef
habitats and species associated with them (Casella et al., 2017, Chirayath and Earle, 2016,
Kiszka et al., 2016). After approximately a decade of experimentation with consumer
drone technology, this report seeks to illuminate the opportunities that customized,
low cost (generally €100-€2000) drone technology can deliver to conservation. Withcentimetre spatial resolution, proximal sensing products derived from drones overcome
the spatial and temporal resolution and cost problem of their satellite counterparts, aswell as the cost and safety issues associated with airplane surveys. Drones’ self-service
capability means that the timing, resolution, extent of surveys can be entirely usercontrolled, offering considerable benefits over other remote sensing tools, particularly
where environmental, climate variables hinder collection from space or airborne
platforms. However, if drone methodologies were completely lacking any complexities,

17

DRONES FOR CONSERVATION

there would be no need for a user guide. Hence, we present a series of chapters thatelucidate the key considerations associated with drone deployments specifically forconservation and ecology, and the emerging issues associated with drone-collected
information.

1.2

Scope

This guide serves as an introductory text for the interested drone conservationist.
We do not seek to provide a detailed introduction to remote sensing or proximal sensing
principles, but through a series of informative chapters, conservation-based case studies
and applications, the technical aspects of drone science or drone sensing will come tolife. We assume that readers of this guide possess a basic background in ecology and/or
conservation and an understanding of basic remote sensing principles (Pettorelli et al.,2018a). Good introductory texts covering drone methodologies in remote sensing andecology and conservation include those by Anderson and Gaston (2013), Duffy et al.
(2017), Sandbrook (2015), Koh and Wich (2012). Importantly, we seek to guide users
towards critical, considered and ethical deployment of lightweight drone technology foranswering a broad range of conservation questions. It is beyond the scope of this reportto consider all types of drone technology, so we focus on lightweight systems, which aredefined in most countries to not exceed a total take-off-weight (including sensors andall batteries) of 7 kg. The lowest weight class generally confers a low legislative hurdle
for users in most regions of the world. The rules governing how, where and when suchaircraft may be flown will change according to local, national and international policy(Chapter 7). All users are expected to read and abide by their country’s civil aviation
authority operational procedures before taking to the skies, regardless of their science
or conservation mission.

1.3

The structure of this guide

Although this guide is aimed at those with little to no knowledge of, or experience with,lightweight drones, the content will address the ever-changing applications of conservation drones to a wider seasoned audience. The authors have made every effort to balance
breadth, depth, and accessibility for more complex material. We cover a wide range ofmaterial starting with the evolution of the conservation drone (Chapter 2);
a literature review summarising the state of the art in drones for conservation science,and key considerations for drone applications (Chapter 3). We then provide advice on
executing a drone survey in 10 clear steps (Chapter 4), followed by details on drone
anatomy (Chapter 5) and the wide range of sensor payloads now available (Chapter 6).
Following this, we explore operational guidelines for flight planning and data collection(Chapter 7), and analysis (Chapter 8). We then shine a spotlight on how WWF areusing drones in operational conservation research (Chapter 9). We capture the techno­
logical limitations of current drone technology, caveats and solutions (Chapter 10); andthen finish by summarising the future potentials and trends in the rapidly evolving drone
industry and how these might benefit conservation scientists (Chapter 11).

A group of wild Sumatran elephants are tracked via drone in the community plantation inMusarapakat, Aceh, Indonesia. © Mahmud Yani/WWF-Indonesia

19

DRONES FOR CONSERVATIONDRONE EVOLUTION
We begin this report by situating drones within their long history of military develop­
ment and experimentation. We, alongside others, argue that this is an important consi­
deration for drone users from all disciplines, because the emergence of drones from amilitary milieu can influence public perception of drone practices (Garrett and Anderson,2017). For such reasons, the appearance of a drone in the field can give rise to a rangeof responses amongst the public, some positive, some less so. Indeed, in some settings,
conservation drone deployments may be met with resistance, fear, animosity, demands forpaperwork, and proof of pilot competence. Humle et al. (2014) argue that within conservation settings, drones may be considered by some to represent the “sinister technologies
of surveillance or be associated with warfare and civilian casualties”, with such negative
perceptions potentially viewed as a return to “fortress conservation, reducing support
for protected areas and undermining the relationships on which successful research andconservation projects are built”. Some agencies will simply refuse to grant permission fordrone flights, on various grounds. We propose that in understanding the drone’s militaryhistory, conservationists will be better equipped to navigate these complex scenarios.
Importantly this can allow for a more sensitive re-situation of conservation drones as
positive forces for good, rather than, as may be seen by some stakeholders, an extension ofsurveillance technologies that could, in some contexts, be considered capable of delivering
harm.

2.1
The first pilotless aircraft
were developed during
the first world war andlaunched via catapult.
For more information visit:https://www.iwm.org.uk/
history/a-brief-history-ofdrones

Military beginnings

Consumer drone technology, like remote sensing and geographic information systems,
has a military heritage (Garrett and Anderson, 2018). The first drones were developed
during the first world war, and launched via catapult. These systems were very large compared to most modern day consumer drones and they were designed for use in reconnaissance missions or as aerial weapons. During world war II, the US radioplane company
produced thousands of unpiloted ‘drones’ for use as gunnery targets. Military applications continued to be the primary focus for drones through the mid twentieth century,with large numbers being deployed during the Vietnam war for delivery of propaganda,
and as military decoys. From this heritage modern drones have evolved to perform amuch wider range of functions, and although the military still use drones widely, they
are no longer the sole user of the technology in today’s world. The word ‘drone’ itself isa simple descriptor that belies its complex origins and taxonomy – yet most drones
possess a unifying capability, described succinctly by Wallace-Wells (2014): “Each ofthese machines gives its human operator the same power: it allows us to project our
intelligence into the air and to exert our influence over vast expanses of space”.
Every drone, if equipped with a camera, can provide a ‘view from above’, a capability long
critiqued by human geographers in the context of the aerial characteristics of the drone
gaze (Klauser and Pedrozo, 2015). Until the recent upsurge in consumer drone technology, the drone was best known for its role in exercising military/government power,
across and within space; exerting superiority over humans (or non-humans) below. Thisconnects the drone’s view from above to a long history of subjugation through aerial
spatial visualisation (Graham, 2016). Through this lens, drones can be considered part ofan aerial assemblage that spans: aerial photography, warfare surveillance, aerial policing, photographic reconnaissance, satellite communications and spatial mapping; all ofwhich have underlying, and associated “power dynamics” (Klauser and Pedrozo, 2015,
Adey, 2010). The top-down view afforded by an aerial camera, if considered in a military

DRONES FOR CONSERVATION

20

context, can give the drone operator a sense of an “inherent superiority” over people orobjects “beneath the gaze” (Graham, 2016, Garrett and Anderson, 2017). Figure 1, takenfrom Giones and Brem (2017) evidences the entwined strands of drone develop­ment,from military beginnings, to civilian appli­cations.

Target Drones
developed

Drones used forreconnaissancemissions

Drones usedas decoy

Drones with real-time
surveillance & radar

1950–1960s

1970s

1980s

Drones for combat,
surveillance andcarrying armaments

Drones forcombat, attack
targets withmissilesMilitary
Civilian

1900s

1990s

2000s

2010s

Drones for mapping,aerial photography

2015

Drones forrecrea­tionaluse

Drones forindustrial inspections & secutirty,
precesion
agriculture

Drones forfilming &broadcasting

Drones forlogistics – first
packet delivery

Figure 1: A timeline of military and civilian uses for drones – taken from Giones and Brem (2017).

2.1

The drone dichotomy in conservation

The dichotomy of the drone led Wallace-Wells (2014) to call for a more nuanced ecological taxonomy to be imposed on drone classification. There are now thousands of different
kinds or ‘species’ of drone, with a diversity of uses for different settings (see Figure 2)– and Wallace-Wells (2014) argues that many of those used by scientists and conservationists could be classified in a separate family to military or police drones. Even within
civilian applications, there is a great diversity of drone use – a conservation drone has different traits compared to a racing drone. Indeed the operational methods of flying and theunderlying purpose for flying, are completely different across the examples shown here.
Such classifications however, are confused by the fact that at the time of writing, widely
available consumer-grade drones such as the DJI phantom, are being used in parallel bydifferent groups: for example, within science and conservation (Rush et al., 2018), as well
as by the military and police (Wall, 2016). Conservation ecology is in fact, a nexus of thespectrum of drone applications – with drones now widely used for surveying and inventory of ‘at risk’ animals (Wich et al., 2015, Linchant et al., 2013, van Gemert et al., 2015)
and in reducing human-wildlife conflict (e.g. using drones to deter elephants from villages(Hahn et al., 2016). Alongside, drones are widely used by anti-poaching agencies (termed“green militarisation” by Lunstrum (2014) or “militarised”/“weaponised” conservation(Duffy, 2014, Wall and McClanahan, 2015), whilst there is new evidence emerging of apoaching ‘arms race’, where wildlife poachers themselves might engage lightweight drone
technology to target their prey more effectively (EcologicalSociety of America, 2018).
Conservation and ecology provide a lens on the complex, sometimes, fuzzy boundaries

21

DRONES FOR CONSERVATION

between drone surveillance and drone science, giving rise to what Massé (2018) terms,“the multiple spatialities of conservation power”. It is precisely for this reason that weemphasize the military beginnings of drones in this report. Most often, this blurring of
definitions can generate confusion amongst stakeholders with whom practitioners may
wish to build trust prior to deployment of drones for conservation-related activities.
Such issues should be critically considered and discussed with stakeholders prior toaerial experiments. Whilst the temptation is often to consider just the methodologicalsteps (e.g. how, where and when to fly) in relation to scientific questions, the history ofthe drone means that conservation drone practitioners should consider also the social,geopolitical and ethical implications of their praxes. Sandbrook (2015), in this frame,
provides an excellent starting point from which ecologists can consider the ethical basisof planned drone deployments.
For further insight into this philosophical area, refer to Adey (2010), Garrett andAnderson (2018), and Chamayou (2015) to unpack this debate in more detail. Instead,
we suggest there is a need to view the drone through a lens of environmental optimism.
Like many geospatial technologies that have proven useful in ecology and conservation,drones are not alone in having military origins. Satellite data, geographic information
systems and toolkits such as Google Earth, all have similar military beginnings, yet havebeen re-appropriated successfully to “socially productive ends” – allowing for moreparticipatory and bottom-up democratic mapping approaches to emerge from a militarygenesis (Garrett and Anderson, 2018). In the past five years, drone metamorphosis has
occurred to such an extent that there is a great diversity of drone activities around andabove us and many imagined futures for what drone technology may deliver, both physically and philosophically, to the human race.

2.3

Hobbyist platforms for science and conservation

Figure 2: Zipline uses drone technology to deliver urgent medical supplies to local
communities. © Sarah Farhat/World BankDRONES FOR CONSERVATION

22

Modern consumer-grade platforms form the basis for most of the drone-based ecologicalor conservation research undertaken in proximal airspace (i.e. close to the ground, within
which most conservation/ecology drones fly (<400 ft /120 m)). The miniaturization ofelectronic components, lighter and cheaper materials, increased computing power on eversmaller chipsets, alongside the miniaturization of digital camera sensor arrays, have madelightweight drones more affordable and accessible (Giones and Brem, 2017). Highly specialized ‘surveying drones’ are also on the market, e.g. from companies such as Leica1, but
their relatively higher cost and presumably, commercially closed-source capabilities, haveprecluded more widespread use within ecology and conservation applications. Amongst
ecology and conservation groups there has been an upsurge in the deployment of commercial hobbyist systems over the past decade, either where drones are configured specificallyfor particular applications, or where systems are flown ‘out of the box’ to collect data
(González-Jorge et al., 2017). In drone sensing there is something of a dichotomy between
the rather low-cost data acquisition method, relying on affordable consumer grade aircraft to capture data, followed by the relatively high geospatial skillset needed to extract
information from those data (e.g. using advanced software to generate point clouds, 2- or
3-dimensional datasets for mapping habitats or species). Arguably, this barrier is similar
with many conservation technologies for example LiDAR (Melin et al., 2017) – the complexity lies in the stage where data are converted into information.
All the same, the workflow of drone science is new and different from well understood
remote sensing methods of the past. Those data were more often captured by sensors
flown on airplanes, navigated by skilled pilots; or from space-borne satellites operated bymulti-national agencies and pre-processed for specific uses. Now, drone scientists are thedata providers, the pilots and the data analysts, and with this, comes a need to understandthe impacts of survey design, photogrammetry, image overlap, ground-control-point
distribution, and camera settings on the quality of the data product generated.

California based
photographer Chris
Willis has integrated
drones into his craft© snapchris.com

1

https://leica-geosystems.com/en-GB/products/uav-systems

DRONES FOR CONSERVATION

23

Fixed wing drones Table 1 provides an overview of the most widely used drones with some highlighted
can cover more area scientific publications showing their use in ecology and conservation applications.
per survey, with To summarise, there are two main families of lightweight drone available for use in ecology
conservation work – the fixed wing, and the multi-rotor system. Fixed wing systems
a longer flight time, but andoffer considerably greater endurance (1–2 hours per battery in some cases) – allowing larger
require a larger space for areal coverage per survey, since they are more aerodynamic. Where local legislation allows –take-off and landing. beyond-visual-line-of-sight (BVLOS) surveys can be carried out effectively with these kinds
Copters have shorter
flight times, are noisier,but more maneuverable,
can hover and requireless space for take-off
and landing.

For more information visit:
Drones - Open Access
JournalJournal of Unmanned
Vehicle Systems
Remote Sensing in Ecology
and Conservation
Remote Sensing ofEnvironment
Remote Sensing - Open
Access Journalof platforms. For this reason they have been put to good use in surveying remote areas ofrainforest, for example. Multi-rotor or copter drones, on the other hand, are less aerodynamic, and deliver lower flight times per battery, but tend to be more stable and maneuverable, and more common on the commercial market than fixed wing systems, becoming themainstay of most ecological and conservation drone research. Advancements in autopiloting
software means that on the whole, multi-rotor and fixed wing systems can stabilize theirflight with minimal need for pilot input. Multi-rotors are noisier than fixed wing drones,
since they have more rotors and engines, and therefore can cause disturbance to wildlife,
which may undermine the purpose of a survey. Hence, flight plans that are sensitive to theseissues should be designed to generate minimal stress amongst target organisms. On theother hand, launch and landing for fixed wing drones requires more pilot skill, more space,and sometimes more infrastructure than multi-rotors which take off vertically. For example,
some fixed-wing systems may be hand-launched while other requier propulsion such as aspring-loaded catapult. We explore these drone types in further detail in Chapter 5.
There are a wide variety of academic papers that now summarise the capacities andcapabilities of these ‘lightweight’ (sub 7 kg) drone systems for ecological and conservation work. We refer readers to a few key papers that provide useful insights, including
Anderson and Gaston (2013), which provide a basis for understanding the capabilities
of different drone platforms of varying sizes and payload capacities, with a particularfocus on terrestrial ecology. Rees et al. (2018) provide a detailed account of the provenand potential uses of drone approaches for sea turtle survey. Woodget et al. (2017)
similarly provide great insights on drone methods for fluvial habitat survey. Many of
the approaches described therein, could be adapted readily to the monitoring of otherspecies and their habitats: across terrestrial, aquatic, and coastal settings. There are also
peer-reviewed journals focusing on drone-based research, for example ‘Drones’, andthe ‘Journal of Unmanned Vehicle Systems’; alongside broader remote sensing journals
which feature articles employing drone methodologies, e.g. Remote Sensing in Ecology
and Conservation, Remote Sensing of Environment, and Remote Sensing. Some of thesejournals have also featured special issues on drone applications in the past, see for example, the Remote Sensing in Ecology and Conservation special issue on “RPAS applications
in conservation and ecology”.

DRONES FOR CONSERVATION

24

Table 1: Examples of lightweight drone systems used in ecological research

MAXIMUM OR TYPICAL TAKE OFF WEIGHT (TOW)INCLUDING BATTERIES AND SENSORS (IF APPLICABLE)

TYPE

MANUFACTURER AND MODELMULTI-ROTOR

DJI Phantom(versions 1 to 4
and ‘Pro’)

Typical TOW is 1.4kg if fitted with standard DJI
camera on gimbal.

€1–2,000

3DRobotics Solo

Maximum TOW of 1.8kg but actual weight willvary depending on user-fitted sensor systems.

€400–800

3D Robotics Y6

Maximum TOW of 1.8kg but actual weight willvary depending on user-fitted sensor systems.

<€500

Draganflyer X6

Payload capacity 2.6kg€10,000

DJI Mavic Pro/Mavic Air

TOW when ready to fly, with built-in camera
is 0.4kg (Air) – 0.725kg (Pro)€700–€1,500

Parrot Anafi

TOW 374 g with built-in camera€1–2K

Skywalker 2013

Variable depending on payload€700–1,000

Parrot Disco

700g, flying time of 45 minutes
top speed of 80km/h€800

TBS Caipirinha

650g typically, if fitted with go-pro camera€500

SenseFly Ebee

700g

€15,000

FIXED WING

COST

25

DRONES FOR CONSERVATIONBUILT-IN SENSOR?

COMMENTSAPPLICATIONS

Yes, Camera. Phantom 4 Pro
includes a 1-inch 20-megapixel
CMOS sensor suitable for stillor video capture.

Ready to fly out of the box. Inbuilt
camera with gimbal, and easy to use
control software. Relatively closedsource compared to 3DR.

Bevan et al., 2015, McLelland et al.,2016, Kiszka et al., 2016, Marcaccio etal., 2015, McNeil et al., 2016

No but there are a wealth of camera
mounts and gimbals than can be fitted
to enable most cameras to be carried.

Ready to fly out of the box, but to fit
sensors or gimbals requires some basic
technical knowledge. Flies with a 3DR
pixhawk autopilot which is fully opensource, so all flight parameters can beobtained easily. Open source Mission
Planner software can be used to planand execute autonomous flights.

Duffy et al., 2018b, Vattapparamban etal., 2016,
Hogan et al., 2017,
Crutsinger et al., 2016,
Fernandes et al., 2018

No, camera mounts can becommercially purchased or 3D printed.

Typically must be built from a kit but isfully customizable. Uses a pixhawk (seenotes for 3DR solo).

Cunliffe et al., 2016,
Puttock et al., 2015

No, users report fixing ruggedized
cameras to the underside using bespoke
fixings.

Ready to fly system, but to fit sensors or
gimbals requires some basic technicalknowledge. Commercial

Woodget et al., 2017,
Woodget et al., 2015

Yes

12 MP camera is integral to the drone

Fernandes et al., 2018

Yes

21 MP camera is integral to the drone

Borrelli et al., 2019

No, must be customized by the user.
Consumer-grade cameras often used,
e.g. Canon S100 operating ‘canon
hack development kit’ (CHDK) for
autonomous triggering.

Uses a HK 2.7 autopilot which iscompatible with open-source Mission
Planner software.

Wich et al., 2015

Built-in 14MP camera

Ready to fly out of the box, automatedtake-off and landing; Parrot FreeFlight
Pro software for mission planning

Cerreta and Kiernan, 2019No, but users report easy fitting of GoPro camera

Equipped with APM2 flight controller,
compatible with open-source Mission
Planner software.

Thapa et al., 2018

Yes – it can include the SenseFly S.O.D.A
RGB camera or be fitted with a Parrot
Sequoia for multispectral surveys

A relatively high-end version of a fixed
wing aircraft but well supported bycommercial suppliers.

Scobie and Hugenholtz, 2016

The Amoron’i Onilahy Protected Area in Madagascar is managed by local communities in partnership with WWF, who protect their natural wealth through ecotourism promoting biodiversity.
© Martina Lippuner/WWF-Africa

27

DRONES FOR CONSERVATION

SO, YOU WANT TO USE A DRONE FOR CONSERVATION?
You are probably reading this report because you are interested in whether dronebased data might be useful for your ecology/conservation application. The chances arethat some of the questions you need answering have already been addressed by others
through experimenting with the technology, and in carrying out scientific or other investigations with drones. In this chapter we will:•

Summarise the current state-of-the-art in drone methodologies
within ecology/conservation;•

Outline the key considerations that all drone operators must address
before taking to the skies (best practices, Figure 8);•

Signpost to sections of this report providing details about the types of datathat can be captured, and how;•

Briefly summarise the operational pitfalls and challenges facing drone
operators in particular situations.

3.1

State-of-the-art drones in conservation

New research has shown that data from drones can deliver improved scientific measurements of natural phenomena compared to human observation. Hodgson et al. (2018), forexample have evidenced more accurate animal counts from drone-based image data. Similarly, drones can deliver more accurate geospatial data at lower cost as compared to othersurveying technologies (Glendell et al., 2017, Castillo et al., 2012) and are also often visuallycompelling and easy for non-experts to interpret and understand – so they can directly
influence and inform policy change in a direct manner (Stark et al., 2018). Drone-captured
data are therefore increasingly being used to support park managers and local communities to monitor and protect their areas in real-time (Ancin-Murguzur et al., 2020, López J,
Mulero-Pázmány, 2019; see section 3.7). In the context of animal ecology, Koh and Wich
(2012) argue that drones offer a non-technical approach for data acquisition at fine spatial and temporal resolutions. The following sections give a brief flavour of the breadth ofscientific applications where drone data have contributed to an advanced understanding of
ecology or conservation related issues.

3.2

Terrestrial flora

In the sphere of terrestrial ecology, drones have been used effectively for low-cost sur­veying of forest habitats for carbon assessment (Mlambo et al., 2017), and for spatial
and volumetric assessment of forest structure (Dandois et al., 2015, Dandois and Ellis,
2010, Dandois and Ellis, 2013, Zahawi et al., 2015). In the Brazilian Amazon, d’Oliveira
et al. (2020) have derived aboveground biomass (AGB) estimations as well as informa­tion on crown structure, leaf area density distribution from drone-mounted LiDAR.
Baena et al. (2018) have shown how drone data can be used to inform terrestrial eco­system assessment and also provide useful information for guiding management strategies for wildlife and plant communities (Lyons et al., 2018b). In drylands, early foun­dational work showed the promise of drone methodologies for mapping major vegetation
types across landscapes – the fine spatial resolution of drone data revealed patterns
hidden within coarser-scale satellite pixels (Laliberte and Rango, 2009, Rango et al.,2006). More recent work has shown that point clouds derived from drone-captured

28

DRONES FOR CONSERVATION

aerial photography can deliver crucial information about desert plant structures and above ground biomass (Cunliffe et al., 2016), leading to developmentof a new reproducible protocol for expanding such observations to a wide
range of ecological systems (Cunliffe and Anderson, 2019). In low stature
grassland ecosystems, new research has proven the capability of drone data todeliver information about grassland sward heights, crucial for understanding
the spatio-temporal distribution of ecosystem services in systems where LiDAR
would not deliver useful data on ecological structure (Forsmoo et al., 2018).
Drones can also offer a new perspective – Liang et al. (2019) demonstrate thevalue of laser scanning data from drone platforms by showing how currently
available off-the-shelf drone-based laser scanners can deliver “excellent treeheight/tops measurement performance”. Although they demonstrate that thegeometric accuracy of stem retrieval is less accurate than terrestrial laser scanning, the “high mobility and fast data acquisition” (ibid) offers benefits over
TLS in forest systems.

Figure 3: A drone image showing dryland vegetation in the New Mexico Desert, taken by a DJI Phantom 4.
© Dr. Andy Cunliffe

DRONES FOR CONSERVATIONMONITORING PLANT BIOMASS WITH DRONE PHOTOGRAMMETRY
Dr. Andrew Cunliffe, University of Exeter

Andy is a Research Fellow investigating the carbon dynamics of terrestrial ecosystems. He uses drone photogrammetry as a versatile tool to collect fine-grain observations of plants and landscapes at sites around the world.
Plants are critical components of most ecosystems, mediating exchanges of waterand carbon between the land and the atmosphere, and forming the basis of most foodwebs. Conservation practitioners can use drones as tools to observe plants, looking
for changes within and between ecosystems that inform understanding of plant health, forage availability,
fuel loads, and ecological responses to environmental change.
Drones can acquire photographs of ecosystems from above in a reproducible and minimally invasive manner.
These aerial photographs can be processed with photogrammetry techniques, generating geolocated mosaic
images and 3-dimensional models. These images can be analysed to detect the presence of particular organisms,
such as invasive species. The models also support extraction of canopy heights and associated attributes suchas biovolume, which can be used to infer aboveground biomass. With repeated surveys, it is possible to monitorchanges in vegetation cover, canopy height and biomass carbon storage through time.

Key advice for the new drone scientist:
1.
2.

Take the time to think about how the remotely sensed attributes relate to the properties
you are interested in measuring.
When working with new approaches, undertake field trials to ensure that your data collection efforts
will meet your needs.

Further information:
Andrew M. Cunliffe, Richard E. Brazier, Karen Anderson. 2016. Ultra-fine grain landscape-scale quantificationof dryland vegetation structure with drone-acquired structure-from-motion photogrammetry, Remote Sensing
of Environment, Volume 183, Pages 129–143.

29

DRONES FOR CONSERVATION

30

3.3

Terrestrial fauna

Within faunal studies, drones have delivered novel data. For example, drone data havebeen used to understand more about the ecology of proboscis monkeys complementing
satellite tracking and habitat mapping (Stark et al., 2018). Orang-utans (Wich et al.,2015) and chimpanzee nests (Bonnin et al., 2018), have been surveyed from drones where
the fine spatial resolution data are essential for distinguishing the canopy characteristics associated with nesting sites. Thermal sensors on drones have been instrumental inmonitoring canopy dwelling animals such as monkeys (Kays et al., 2019). Van Gemert etal. (2015) have pioneered the application of automatic counting systems to drone data forthe purposes of population counts, whilst Weimerskirch et al. (2018) have used drones toadvance understanding of animal behaviour and physiology. On the terrestrial – marine
interface, emerging work by Nowlin et al. (2019) has begun to evaluate the role of drone
data in monitoring human behaviour within conservation projects. Through this work
they discuss the “legal and regulatory landscapes that scientists confront when people are
their primary study subjects” and resultantly offer a useful set of guidelines for researchers studying human interactions with natural resources in the marine environment.

Figure 4: Orangutan nest spotted during aerial drone survey in Bukit
Puton Forest Reserve. © WWF-Malaysia/Mazidi Abd Ghani

31

DRONES FOR CONSERVATION

Figure 5: Fishing boats offloading their catches in Kayar, Senegal. © Aurélie Shapiro/WWF

3.4

Marine/coastal flora

In the near-shore coastal zone, seagrass surveys have been successfully delivered bydrone (Duffy et al., 2018b). In sand-dunes, drones have been used to deliver spatial ecological data, and volumetric geomorphic information (Duffy et al., 2018a, Mancini et al.,2013). In marine turtle conservation Varela et al. (2019) have demonstrated the value offine-grained coastal topographic models delivered from structure-from-motion photogrammetry workflows for assessing coastal squeeze and the impact of rising sea levels on
turtle nesting beaches. Coastal assessment of vegetation zones using lightweight drones
has also been carried out successfully by Ventura et al. (2018). Work by Gray et al. (2018)evidences that drone data are “highly effective” for training classification algorithms
and validating fine-spatial resolution satellite data: in their example, they demonstrate
this approach with regards to coastal habitat mapping products generated from coarser-­grained satellite data.

DRONES FOR CONSERVATION

32

3.5

Aquatic systems

In aquatic systems the presence of water and spatial/temporally variant surface structures (e.g. waves, whitecaps) can create uncertainty in drone data making it difficult tostitch together images or generate high quality imaging products. There is cutting edge
science being undertaken to try to address this problem, using ‘fluid lensing’ (i.e. “using
water-transmitting wavelengths to passively image underwater objects at high-resolution
by exploiting time-varying optical lensing events caused by surface waves” (Chirayathand Earle, 2016)) to overcome the problem. This technique relies on experimental
complex algorithms to model the effect of surface motion on remotely sensed signals. It
would probably be out of reach of most conservation practitioners at present, but in the
future it is possible that it may form part of more standard marine processing workflows. On the other hand, if ideal conditions exist, with minimal wind, there are great
opportunities for conservationists to benefit from drone data. Coral reef scientists havecapitalised on the drone methodology because the shallow nature of many reefs, whichmeans that in calm conditions, the reef structure can be effectively sensed from drones.
For example, Casella et al. (2017) show how submerged reef morphology can be obtainedby applying photogrammetric workflows to overlapping aerial images. Marine mammals
have received much attention in this sphere – with surveys of dugongs (Hodgson et al.,2013), sharks and rays (Kiszka et al., 2016), seals (Pomeroy et al., 2015), jellyfish agglomerations (Schaub et al., 2018), cetaceans (Gray et al., 2019) and whales (see case study,
page 33). Indeed, in the case of cetaceans, Gray et al. (2019) have demonstrated thatin using state-of-the-art photogrammetric workflows and neural networks, it is possible
to correctly classify whale species from drone imagery with 98% accuracy (57/58) for
humpback whales, minke whales, and blue whales – meaning that automatic recognitionof species from image data is a possibility in the future. Also in whales, recent work by
Christiansen et al. (2019) has highlighted the capacity for ‘weighing’ marine mammals
vicariously using photogrammetry techniques that describe the volumetric characteristics of individuals. In the freshwater domain, there are also studies which are starting toshowcase the capability of drone technology for delivering new insights into the structureand function of rivers (Woodget et al., 2017, Husson et al., 2016, Husson et al., 2014).

Figur 6: Drone-based survey of Amazon river dolphins, Brazil. © Mauro/AFPDRONES FOR CONSERVATIONUSING DRONES TO COLLECT WHALE LUNG SAMPLES
Dr. Vanessa Pirotta, Macquarie University

Vanessa Pirotta is a conservation biologist and science communicator who has
recently completed her PhD at Macquarie University. Her research focuses on identifying conservation gaps for cetaceans : whales, dolphins and porpoises.
As part of Vanessa’s PhD, waterproof drones were designed and built to sample
whale lung microbiota for an assessment of whale health. Previously, sampling whale
health was limited to whales that had either stranded, in which case their health wascompromised or those that were hunted. The transition to sampling from live, free swimming whales originally
included poles with petri dishes extended over whale blowholes from boats. This was and still is a successful
method to collect lung microbiota however, this application requires close boat approaches to whales, which canbe dangerous and invasive.
The application of drones to sample humpback whale lung microbiota off Sydney has been incredibly successful.
In collaboration with industry (Heliguy Scientific), a remotely operated flip-lid mechanism on the drone allows apetri dish to be open and closed during flight to minimise sample contamination. From this, lung microbiota andviruses have been collected via this non-invasive method.

Key advice for conservation practitioners:
1.
2.

Collaborate with industry to develop tools for your research.
Go beyond your field of expertise and learn from others doing similar things in different environments.

Further information:
Pirotta, V., Smith, A., Ostrowski, M., Russell, D., Jonsen, I.D., Grech, A., et al. (2017). An economical Custom
Built drone for assessing whale health. Frontiers in Marine Science, 4.
www.vanessapirotta.com

Whale lung sampling in action. Using drones to collect lung microbiota for a remote assessment of whale
health off Sydney, Australia. © Vanessa Pirotta

33

DRONES FOR CONSERVATION

34

Example aerial photographs of the dorsal surface of a southern right whale, used to measure body length
and width (W) at 5 % increaments along the body axis from 5 % to 85 % body length from the rostrum(white arrows).

Lateral side of the same whale, used to extract body height (dorso-ventral distance) along the samemeasurement sites. The white solid lines indicate the location of the predicted girths (at 25,50 and
72 % BL from the rostrum) along the body axis (dotted white line).

A 3D model of the same whale, used to estimate body volume. The cross-sectional ellipses illustrate thevariation in height-width ratio across the body of the whale.

Figure 7: Using drones to estimating body characteristics of cetaceans– from Christiansen et al. 2019.

35

DRONES FOR CONSERVATION

3.6

Human-drone-wildlife nexus

Drone ‘interference’ has long been the concern of ecologists, because drones create visualand noise disturbance, and they occupy the same airspace as birds. Thankfully, there area great many papers evaluating the ethical implications of drone operations near wildlife,
or in ‘wild’ spaces. Lyons et al. (2018a) studied bird behavioral changes towards drones
during the breeding season, as well as interactions with raptors, and effects on nesting
birds in large colonies. They report that in more than 70 hours of flying they encounteredno ‘incidents’ with birds, despite some aggressive behaviour from solitary breeding individuals. Our own experience from hundreds of hours of drone flights is similar – often
birds (particularly large raptors or corvids) will notice the drone and find it of interest.
We have not experienced any bird attacks on our drones, both multirotor and fixed
wing. Corroborating this, Vas et al. (2015) showed that across 204 approach flights with
quadcopter drone, 80% allowed approaches to within 4 m distance with no measurable
behavioural effect of approach speed and drone colour on birds, with a slightly stronger
reaction to drones approaching vertically. They recommended launching drones >100
m from any target organisms and “adjusting the approach distance according to species”(Vas et al., 2015). Amongst non-birds, the physiological response of large mammals todrone stimuli has been tested. American black bears showed raised heart rates when
exposed to drones, with a declining physiological response with repeated exposure(Ditmer et al., 2019). Pomeroy et al. (2015) studied grey and harbour seals in the UK withdrones and showed ‘variable’ responses to UAS flights, which they explained as being
related to the animals’ prior exposure to disturbance. In fur seal surveys, which would
normally have to be undertaken on foot, McIntosh et al. (2018) showed that “with appropriate testing and ethical consideration; for many situations, RPAS can perform surveys
with increased frequency, higher data resolution [sic] and less disturbance” than in situ
methods. For those seeking general guidance about best practice for using drones aroundnon-humans, we point readers to the work of Hodgson and Koh (2016) who provide a
simple set of points (we have distilled these in Figure 8) for guiding all drone surveys.
We argue that these guidance points are pragmatic for all drone users regardless of thesurvey type or target species. Further to Hodgson and Koh’s (2016) guidance points,
Mulero-Pázmány et al. (2017), and Sandbrook (2015), provide excellent critical reviews
covering disturbance and ethics of drone surveys that all conservation and scientific practitioners would do well to read in advance of any airborne operation.

3.7

Protected area management

Well-managed protected areas (PAs), including sustainable use PAs with local traditional
communities within, can play a great role in forest conservation, providing protection
for biodiversity and serving as a reservoir for future restoration efforts. However, poorly
governed and under-resourced PAs are unlikely to withstand the growing pressures they
face, and while protected areas must be expanded it is imperative that they are also better
managed and monitored. Monitoring and protecting vast PAs and wildlife, with limited
resources and small teams, is a huge challenge in many tropical forest-rich countries,
but conservation technologies such as drones can play an important role in assisting
front-line conservationist and complementing resources to manage and protect PAs(Ancin-Murguzur et al., 2020, López J & Mulero-Pázmány, 2019).

DRONES FOR CONSERVATION36

ADOPT THE PRECAUTIONARY PRINCIPLE IN LIEU OF EVIDENCE.
••

Extra care should be taken if endangered species or sensitive habitats are
involved.
The range of animals and environments evaluated for drone sensitivity
is limited – remember that your target organism’s response may be
unexpected. Seek expert advice if unsure.

UTILISE THE INSTITUTIONAL ANIMAL ETHICS PROCESS TO PROVIDE OVERSIGHT
TO UAV-DERIVED ANIMAL OBSERVATIONS AND EXPERIMENTS.
•

Ensure all drone methodologies are in accordance with approved
institutional ethics permits.

ADHERE TO RELEVANT CIVIL AVIATION RULES AND ADOPT EQUIPMENT
MAINTENANCE AND OPERATOR TRAINING SCHEDULES.
••••

Note local restrictions and national laws.
Where rules are not clear, exercise extra caution.
Regularly service drone equipment and keep maintenance/flight logs.
Seek approval for flight from indigenous or local communities whereappropriate.

SELECT APPROPRIATE UAV AND SENSOR EQUIPMENT.
•••

Choose the right drone to keep noise and visual stimulus to a minimum forboth target and non-target organisms, considering motion type, shape, sizeand colour.
Consider modifying drones if necessary to reduce noise or disturbance.
Choose a sensor that enables sufficient data capture from a safe distance.

EXERCISE MINIMUM WILDLIFE DISTURBANCE FLIGHT PRACTICES.
••••

Locate site launch and recovery sites in advance and away from animals(out of sight if possible)
Keep your distance from animals at all times during flight.
Avoid threatening approach trajectories and sporadic flight movements.
Develop protocols that minimise disturbance to your target species andothers living around them.

CEASE UAV OPERATIONS IF THEY ARE EXCESSIVELY DISRUPTIVE.
••

Monitor non-human and human behaviour during the drone flight.
Cease drone operations if the response of subjects is adverse.

DETAILED, ACCURATE REPORTING OF METHODS AND RESULTS IN PUBLICATIONS.
•

Ensure that you share your methodologies and experiences with othersby undertaking reproducible, traceable research. Good practice will guide
further good practice by others.

Figure 8: Seven points of good practice for drone operations – adapted from
Hodgson and Koh (2016).

37

DRONES FOR CONSERVATION

On top of being used for wildlife and vegetation studies, drones can be a great asset toassist park managers and local communities to monitor and protect their areas. In thecontext of PA management, drones have been used to assist a multitude of tasks such as
anti-poaching patrolling (Hambrecht et al., 2019); forest fire detection and fighting (Ferreira et al., 2019, Merino et al., 2012); to document illegal logging and mining(Koh & Wich, 2012); to support search and rescue (Burke et al, 2019, Goodrich etal., 2008); public-use (Ancin-Murguzur et al., 2020, Sabella et al., 2017); mapping(Paneque-Gálvez, 2014, 2017, d’Oliveira et al., 2020), among other uses.
Nonetheless, the use of drones for PA management is restricted by many factors, suchas cost and technological constraints, as well as practicality and ease of use. Often mostcommercial drones have an insufficient range and flying time to cover PA’s vast areas, but
technology has evolved rapidly, and localized use of drones has been promising. Legaland ethical implications of using drones for PA management also need to be carefully
taken into account as, many countries have restrictions for flying drones beyond thevisual line of sight or above a certain altitude, or there might be cultural, religious orpolitical sensitivities with regards to traditional communities.
Despite the challenges, drones can increase the detail and efficiency of PA monitoring
efforts, be a great tool to assist management, and help to monitor conservation impacts
and threats. Furthermore, the low cost and time economy of applying drones for tasks
such as mapping or forest inventory, as opposed to traditional fieldwork, can increase
the detail and efficiency of data gathering and assessment, more comprehensively, ona larger spatial scale, appropriate temporal interval, and at a finer resolution. Drones
can also be used paired with satellite images, which can previously detect early signs ofdisturbance, in areas where the drones can be rapidly deployed for further
investigations and documentation.

Figure 9: Training Indigenous groups in the Amazon forest to monitor forest fires anddeforestation with the help of drones. © Marizilda Cruppe/WWF-UK

The Quirimbas National Park and UNESCO Biosphere Reserve in Northern Mozambique is home
to rich marine resources, supporting a vibrant fishery. © WWF-Mozambique

39

DRONES FOR CONSERVATIONEXECUTING A DRONE SURVEY IN 10 CLEAR STEPS
Here we present a typical workflow for successful execution of a drone-basedlandscape survey and the relevant chapter of this report to provide more information.

STEPCONSIDERATIONSCHAPTER1. Form researchquestion/selectstudy site

Are drones the optimal tool for this task?
Do you have access to equipment and relevant
expertise?
Are there any legislative hurdles or
considerations, are permits required?

3, 5, 6 & 7

2. Equipment
selection andpreparation

Which type of drone is best suited to the datacollection?
Which sensor will capture data at desired scale/wavelengths?

5&6

3. Test operationof equipment
and sensor
capabilities

Did you test the equipment in a ‘safe’ testing
environment?
Does the technology perform as expected?
Does the sensor collect data suitable for yourapplication?

5, 6, 7, 8 & 10

4. Study site
assessment

Is a license or permit required to fly?
How accessible is the site?
Is there a safe spot for take-off and landing
and do you have landowner permission
to access this area?
What hazards are present at the site?
Can they be seen using satellite imagery
or only in person? (e.g. telegraph cables).
Are there any airspace restrictions?

3&7

5. Flight planning

What is the footprint of your sensor?
Do you require redundancy in the datacollected (e.g. double the number of photos)?
Do you require redundancy in hardware?
Check weather forecasts – implications
for safety and data quality.

3, 6, 7 & 10

6. Survey Flights

Do you have the required personnel tooperate safely?
What are your emergency plans should
something go wrong?

7 & 107. Backup data

Data should be backed up in the field if possible,
or at least removed from the drone/sensor after
each flight (if multiple flights are undertaken).
Data should be backed up when out of the field(i.e. onto the cloud or external hard drives).

8

8. Clean data andpre-process ifnecessary

How are you going to organise and store
the data for processing?
Methods and workflow for removing
unwanted data to streamline processing

8

9. Process data

Would a test run with a data subset help
identify issues in processing?
Do you have enough storage for theprocessed data?
Do you have the necessary software andhardware?

8

10. Disseminate
information

Processing software such as photogrammetry
can produce a lot of information. Distil what
information is critical to your project.

8

“The hidden forest” showing differences in photosynthetic activity based on
Near-Infrared-Reflectance, this mosaic was created from 431 images takenin the Southern Black Forest, Germany. © Adrian Meyer

41

DRONES FOR CONSERVATIONDRONE ANATOMY
Web search an image with the keyword “drone”, and you will likely be presented withpictures of commercial multi-rotor drones (Figure 10). These have become synonymous.with the description and definition of a drone and probably justifiably so. Yet, there
is an entire taxonomy of drones across the spectrum from military to civilian, research torecreation. Wallace-Wells (2014) writes, if you were developing “a taxonomy to describe
all machines, these drones would not belong to the same species. They would probably
not belong to the same phylum.” Drone technology has diversified so quickly, with over
1,500 different kinds of drones being manufactured, with so many applications, resulting
in “a whole flying-robot ecology so vast that to call every one by the same name can seemabsurd.” Multi-rotor drones have certainly inspired an entire consumer market, spawning new opportunities in science, commerce and play.

Figure 10: The consumer drone market is largely comprised of multi-rotor drones. © University of Exeter Drone Lab

As with all things, and despite the versatility and dominance of the multi-rotor within thedrone world, there are flaws and limitations that may not make it the most suitable tool
for a conservationist to capture the required data. An understanding of the typical abilities and limitations of each type of platform can help users make an informed decision inchoosing the correct tool for the job, as part of any overall mission plan. Limited funds,
difficult terrain, remote locations and inexperience are all problems that can be anticipated and mitigated (Duffy et al., 2017), whether fully or in part, with a small amountof drone anatomy knowledge going a long way in helping to secure the capture of therequired data.

DRONES FOR CONSERVATION

42

A fundamental reason to have a deeper understanding of the anatomy of drones, is oneof safety. This is not just for the pilot, wider team or population at large, but also for theenvironment in which the operator(s) are working in. Without a working knowledge of
how your drone functions, and therefore its limitations, accidents related to misuse canlead to injury and property damage, animal disturbance (adverse physical responses,
stress events; (Ditmer et al., 2015, Ditmer et al., 2019, Hodgson and Koh, 2016, Mulero-Pázmány et al., 2017)), plastic pollution, noxious gases and even fires, all of which,depending on the local environment, could be potentially catastrophic.
There are a myriad of forum posts and other sources of information that discuss anddebate the qualities and specifications of drone components, and the physics of flight iscomplex at best, especially for those not versed in mathematics, physics or engineering.
The aim of this chapter is to synthesise this knowledge and introduce the reader to thevarious types of aircraft platform available for use. In this chapter we provide an insight
into what can be expected from each type of platform with regards to its flying capabilities and limits, along with a dissection of the major components that come together toform a drone, for those with a non-technical background. We include essential elementsof safety and law that are vital to successful operation and deployment.

5.1

Aircraft types

As described by DeBell et al. (2015), there are four main types of drone; fixed wing, multi-rotor, tethered (line flown) kite or balloon and lastly, blimp (the latter can be poweredor tethered). More traditional helicopter-like aircraft (single large rotor, smaller stabilising tail rotor) can be used as drone platforms, but tend to be more of a niche product,with drone specific airframes (e.g. allowing accommodation for extra electronics required
such as the autopilot) not being widely available. Traditional helicopters have their merits for surveying – they tend to be more stable and efficient than multi-rotors – but theirmechanical complexity generally precludes them as a low-cost drone option, and hence
we do not add further discussion of those platforms here. Whilst there has also been
recent development with blimp drones, that focus has shifted towards either indoor useor systems that are beyond the budgets discussed in Chapter 3 and as such the focus inthis chapter will be placed on the other three major types of drone which are widely usedwithin the environmental sciences.
The more complex a system is, the greater the chance of increased costs, reduction in
long-term stability, and potential decrease in the reliability and robustness of the systemitself. For a conservationist wanting to collect remotely sensed data, the most straightforward option is the one most likely to succeed, and this may mean that choosing a simple
kite or balloon could in fact be the best option (Duffy and Anderson, 2016), especiallywhen factors such as cost and transportation of equipment, remoteness, wind speeds,
terrain and above sea level altitude are taken into consideration. It is also why simpler, low cost options may be favourable to expensive proprietary systems, which have
replacement parts or entire components readily available, and in some instances flightcontrols that have been simplified with limited functionality for the novice pilot.

43

DRONES FOR CONSERVATION

5.1.1

Tethered balloons and kites

The simplicity of these platforms is their strength. Tethered balloons and kites are mostly
self-explanatory. Drone kites for aerial photography or Kite Aerial Photography (KAP)
are fixed single line so they are easy to fly, and stable. They are usually constructed outof a lightweight and robust ripstop nylon material to create a simple airfoil. Tethered
balloons can be constructed out of a number of different materials, but generally lookexactly like the latex globes we are all familiar with. Balloons and kites don’t require
power supplies, meaning they can operate more consistently in remote locations, or inareas with limited access to power supplies or high capacity renewables. It is only theweather conditions that present limiting factors. The main difference between balloons and kites is their respective capabilities in wind. Whereas a kite needs wind tofly, balloons don’t function well in windy conditions. Both systems are more suited toapplications based on aerial photography, as opposed to data collection requiring video
or motion sensitive devices (i.e. multispectral and hyperspectral sensors). Where location
based data are required, utilising GPS enabled cameras or smartphones (Anderson et al.,2016) allows a balloon or kite user to collect geo-positioned aerial photos. Neither kites
nor balloons are designed to carry heavy payloads, with typical balloons having a payload
capacity of 0.2–0.3 kg, whereas kites can carry upwards of 1 kg. Despite their inherent limitations, kites and balloons can be effectively used in applications where otherdrones may not be viable due to wind conditions or terrain. Whilst kites and balloons cansometimes help in challenging environments, this can also potentially present personalhazards. As kites and balloons are tethered, they must be manually manoeuvred over thearea of interest. Areas with difficult terrain or obstacles may not be conducive, or require
extensive physical effort, to effectively manoeuvre the equipment during surveys.

Balloons and Kites
can remain airborne
as long as there is wind,affording the opportunity
to cover large areas,
but cannot be preprogrammed forsurveys like drones.

Since neither kites nor balloons require power to remain aloft, the area they are able tosurvey is principally determined by the physical condition of the operator, and the ease of
traverse of the terrain. However, as balloons are able to remain aloft for 2–4 days and kites
are able to remain airborne as long as there is a suitable wind, both possess the potential tocover large areas. Static survey heights or exact repeated surveys are also difficult as, unlikewith fixed wing or multi-rotors with autopilots, a defined flying height or flight path cannot
be specified or programmed and is subject to wind conditions. As such, if repeat surveys
with identical surveying methods are required, un-powered systems may not provide therequisite level of pilot control. For analyses involving photogrammetry derived products,
such limitations can now be overcome with complex monte-carlo based modelling methods
which allow the resultant survey-to-survey uncertainties to be accounted for (for details see
Duffy et al., 2018a, James et al., 2017b).

5.1.2

Fixed wing

Fixed wing drones (e.g. Figures 11, Figure 12), are most recognisable by their visual
similarity to piloted aircraft. They have a long body (fuselage), typically cylindrical ornearly cylindrical in shape, with rigid, immobile, wings extending from the fuselage at
outward angles. Modern fixed-wing drones are not strictly limited to this shape alone,with a broad variety of forms and functions. These drones owe much of their development
to the traditional radio control enthusiast community. Early research employed model
aircraft equipped with 35 mm film cameras, but at the time wider adoption was limitedby the high level of expertise required to build and fly these machines. As discussed in
Chapter 1, and in large part due to the burgeoning First Person View (FPV) community,
there are now numerous airframe designs available that offer excellent, low-cost, versatile
platforms for collecting proximal remotely sensed data. Numerous examples of fixed-wingdrones can be found at ConservationDrones.org along with detailed guides for purchasing

44

Numerous examples of
fixed-wing drone models
and detailed guides forpurchasing or building themfrom scratch are available atConservationDrones.org

DRONES FOR CONSERVATION

and building them from scratch (Figures 11, Figure 15; Wich, Serge & Koh, Lian Pin,2012). Aside from build-your-own options, there are a variety of more expensive, readyto-fly fixed wing survey drones, equipped with a variety of built-in sensors. These include
the Ebee survey drone (Figure 12), which can be flown straight out of the box, but the costof these often exceeds €10,000 and thus is only a viable option for those with access tolarge budgets.
One of the key considerations when using fixed-wing drones is the amount of space
available for take-off and landing. For novice users, linear take-off and landing must be
into the wind. Creating a suitable area for linear take-off and landing requires enoughexcess space to accommodate necessary adjustment due to changes in wind direction,
without introducing hazards such as bushes, trees, vehicles, or buildings. To identify theamount of area required, a simple formula can be used where a typical landing approach
for a fixed-wing drone is utilised (a glide slope with the recommended maximum novice
pilot value of 10 %; Figure 13). Applying this calculation from a flying altitude at last
waypoint of 50 m, then the length of glide slope (or distance required for landing) would
be 500 m.
Wind direction for take-off and landing, the need for space and, in some instances, alaunch system that typically uses something akin to a catapult or bungee, also make fixed
wing launches slightly more complex with regards to the overall autonomy when compared to other drone systems. Vertical take-off and landing (VTOL) fixed wing drones
are now commercially available, and being tested for use by delivery companies such as
Amazon (Figure 14). These are commercially expensive platforms but they offer theadvantages of more controlled multi-rotor-like take-off and landing capabilities with theefficiency and glide of fixed wing systems in flight. At the time of writing these platforms
tend to be more expensive than standard fixed wing systems and they are not widely
tested within conservation science, so we do not discuss these further. Perhaps in the
future these will become more widely available at lower cost as the technology develops.

Figure 11: Custom-built fixed wing drone. X-UAV Skua frame with 3DR Pixhawk autopilot, uBlox M8N GNSS,
Purple Power PO-3548-1100 Professional Brushless Motor, 10x6 wooden propeller, 60A t-motor ESC, FrSky digital
metal servos and 10000mAh battery. ©University of Exeter DroneLab

45

DRONES FOR CONSERVATION

Figure 12: Commercial fixed-wing eBee survey drone. © Tegan Sampson

Altitude at last waypoint = 50m

Distance to land at 10 % glide slope = 500m

Figure 13: Calculating landing position for fixed wing drones.

Figure 14: Amazon Prototype Prime Air Drone. © Amazon

DRONES FOR CONSERVATION

46

With regards to payload, most lightweight, fixed-wing drones can carry 0.5 kg off-theshelf, but could be capable of carrying 1.5–2 kg if components are carefully selected ordesigned rather than relying on pre-made or almost ready to fly (RTF) systems. A flighttime of at least 30 minutes should also be expected and up to an hour is easily achievable.
Typically a hobbyist-grade fixed-wing drone such as those used by the organisation “Conservation Drones” (Figure 15) is capable of covering from 10–100 ha in a single flight,
when flying within the UK and EU-wide legal limits of 500 m line of sight and 120 m
above ground level (AGL). Because the speeds at which fixed wings operate are generally
much greater than that of other drone options, it is best to consider using these for larger
area surveys. Consider that fixed wings also need to fly with more altitude to reduce any
potential blur in data captured (for example, from a digital camera) due to the relative
ground speeds. Fixed wings are manoeuvrable, but a change in direction needs to happen
over a wider scale than that of a multi-rotor and flying at lower altitudes could potentiallyresult in either unsafe turns or gaps in data.

Figure 15: A low-cost fixed wing system used by “Conservation Drones”

Wind is a major factor in any type of drone operation, and the type of airframe in a fixedwing system is important to consider for successful operation in windier conditions. An
aircraft with a dihedral wing (a wing that angles upward from the body towards the tip;
Figure 16), can provide some inbuilt flight stability, exclusive of the autopilot. However,this design may be more susceptible to poor flight in higher wind conditions. The samecan also be said of airframes that incorporate a large fuselage, since wind shear or gusts
can act upon the body to render the aircraft unstable. Flying wing designs (e.g. see eBee
design in Figure 12), which are popular in more expensive, proprietary drone systems,
offer better performance in windy conditions due to their lower profiles, but tend to needto fly at higher speeds and may exhibit unstable behaviour when operated in manualmode. The level of manual control is worth consideration for inexperienced operators,
and as per the discussion in Chapter 7, is an integral part of any safe operation.

47

DRONES FOR CONSERVATION

One final consideration for fixed wing systems is the cost and fragility of the onboard
sensors that are being used to collect data. In most instances, and certainly in the lower
cost end of the drone market, fixed wing will offer more protection for the sensors inquestion. Many can be housed on top of a wing or within the fuselage for protection in
the event of a propulsion failure, and there is the opportunity to bring a fixed wing down
through a glide (as per a normal landing) or using a parachute deployment to slow therate of fall. This greatly reduces the likelihood that fixed-wing sensors will experience thefull force of a vertical fall from height. The QuestUAV ‘data hawk’ is a commercial fixed
wing ‘flying wing’ style system that offers parachute landing capability for precisely thisreason (Figure 17).

DihedralMore lift

Less lift

Figure 16: Depiction of wing dihedral - the upward angle of a wing in relation to its
body/fuselage - is designed to have an impact on flight stability and impact on flightstability

Figure 17: Parachute landing capability for a fixed wing drone © Quest UAV.

DRONES FOR CONSERVATION

48

5.1.3

If your objective is tocapture stabilised video,
a multi-rotoris the best option

You can also build yourown multi-rotor within a
500–1,000€ budget thatoffers stable, repeatable
missions with the ability tocarry custom payloads.

Multi-rotor drones

Multi-rotor drones come in all shapes and sizes, but are hallmarked by arms that protrude from a central body and house a motor and propeller on each (Figure 18). Arms
are always even in number and range from four, six, or even eight on any given machine.
If your objectives require capturing stabilised video, for wildlife monitoring or observation perhaps, then the multi-rotor is without doubt the best option available. Many
commercial off-the-shelf systems now come complete with built-in gimbal mounted
cameras, which are purposely designed for image stabilization and angle control. Within
this market, the Chinese company, DJI have come to dominate the market by offeringhigh quality products that are relatively affordable (from €700–€5,000 depending on
capability) and simple to use. Even though the primary focus of DJI has been video,
they have also become popular within the scientific community for their ease of flight,
programming and the high quality of still image capture. Most of their systems now comeready equipped with auto take-off and landing, GPS failsafes, automatic geofencing andobstacle avoidance as standard. If you want to plan and collect fully autonomous flights
using pre-programmed waypoints, DJI provide software for this (currently called ‘groundstation pro’). For other non-DJI systems, there are several options available such as
droneDeploy, and Pix4D.
If you wish to attach third-party sensors to drones there are a range of options. A California-based company called MAPIR2 offer high quality, low cost upgrades like post-market
mounts for near-infrared cameras for DJI multi-rotor systems. Unfortunately, due tomarket forces, DJI’s competitors who previously offered multi-rotors with more flexible
and open-source features are not so widely available, as both 3D Robotics and HobbyKing have discontinued their open source Arducopter-based products. However, there
are still pre-built options available from small manufacturers such as Drotek in France3.
For the more adventurous, and because of their mechanical simplicity, it is also relatively
simple to build your own multi-rotor easily within a €500–1,000 budget that will offer
stable, fully automated, repeatable missions with the ability to carry custom payloads –Figure 19 is one such self-built example, costing <€500 (without sensor).

Figure 18: Commercial drones: left is the 3DR Solo and right is the DJI Phantom 4.
Both include gimballed cameras, weigh <2kg take-off weight and can fly for
15–25 minutes on a single battery (<1,500€). © University of Exeter DroneLab2

https://www.mapir.camera/3

https://drotek.com/

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Figure 19: Modified Tarot 650 fram quadcopter with 3DR pixhawk autopilot,
multistar motor and propellors, ublox M8N GNSS and 1000mAh battery.
© University of Exeter DroneLab

There are overall fewer factors for a pilot to consider in conducting a safe and successful
mission with a multi-rotor drone. One of the key advantages of the multi-rotor is the
VTOL capability. It is not uncommon for a pilot to find themselves in an environmentthat does not provide the necessary space for take-off and landing with a fixed-wingdrone (Duffy et al., 2017). Multi-rotors are also not affected by wind direction in thesame way that fixed wing systems can be, and therefore provide more flexible use cases.
The design of the multi-rotor also means that manoeuvrability is very precise. Relative
to their fixed-wing counterparts, multi-rotor systems are capable of changing direction
in small areas. The ease with which multi-rotors can be manoeuvred also results in fully
automatic missions being much more straightforward to execute, and in some cases, oncethe pre-programmed mission has been uploaded to the multi-rotor, pre-checks completed and the motors started, only a single tap of a button or flick of the switch can allow
the machine to complete its task with virtually no pilot input.
As with fixed-wing drones, the typical payload capacity of a lightweight, off-the-shelf
multi-rotor tends to be up to 0.5 kg. However, custom multi-rotors can be built withrelative ease, increasing payload capacity to 2.5–3 kg if you carefully select components
rather than relying on pre-made systems. A typical flight time of 15–25 minutes can be
expected although multi-rotor flight time is affected much more by factors such as payload and wind speed by comparison to fixed wing, and an operator could quite easily findthat only 10-15 minutes is available for the safe, conservative completion of a mission. It
may be necessary to experiment with airspeeds to establish a “sweet spot” for maximising
distance, while maintaining data quality.

Expect to achieve Pilots should expect to achieve 20–30 ha of coverage when flying at the typical legal limit
20–30 ha of of 120 m AGL with a low-cost, lightweight multi-rotor. However, the precision of mulalso means that, as is the case with tethered kites and balloons, the altitude thatcoverage during ti-rotors
they can fly at to collect data is much more flexible than that of fixed wings, which must
one multi-rotor flight fly at a greater altitude in order to reduce blur. Because of relative ground speed and theat the typical legal blur it causes to image data, the lower an aircraft flies, the slower it must also fly. Whichlimit of 120 m AGL. means fewer ha may be covered within a single mission due to the slower speeds andlower altitude. This is particularly the case when collecting precision data with required
overlap, for photogrammetry or 3-dimensional mapping.

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50

5.2

Flight control software isdependent on the drone
and piloting device (laptop,
phone or tablet).
For a list of common flightplanning and control
software, see table 5,chapter 8.

Flight control

There are two main components for drone flight control: the autopilot and the Global
Navigation Satellite System (GNSS). The autopilot is a combination of both hardwareand firmware that functions as the machine brain, controlling a range of functions, from
simple stabilisation to fully automated missions, including the triggering of the sensor
payload. The autopilot communicates with associated software, enabling remote controlof the drone, typically via a laptop or tablet. The GNSS, whilst not entirely necessary forflight, provides the location information to the autopilot, thereby facilitating autonomy,
and can associate sensor-collected data (e.g. aerial imagery) with temporal and spatial
coordinates, as well as providing real-time tracking of the drone for the pilot.
Physical hardware options (autopilots) at the low-cost end of the self-build drone market
are varied, but the firmware and associated software that goes with them is limited.
DJI does offer a stand-alone autopilot, however the firmware is proprietary and locked,
preventing a user from amending certain programs and is far less customizable thanthose of other manufacturers. Furthermore, DJI’s autopilot is specifically for multirotors whereas autopilots that run the PX4/Ardupilot firmware allow for conversion of
any type of radio-controlled vehicle. The PX4/Ardupilot can also communicate with awider variety of sensors and associated software allowing a greater level of customization, which makes them especially popular in the self-build community. There are othertypes of flight controllers which provide some basic features and allow for an on-screen
display (OSD) but these are squarely aimed at the FPV community and aren’t as muchuse for survey purposes.

Figure 20: Assembling low cost multi-rotor drones using a Pixhawk autopilot in
the Brazilian Cerrado. © WWF-Brazil

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Because drones are capable of flying beyond radio control and/or falling out of the sky,
it’s important to have an autopilot that can provide assistance in the form of failsafes.
Some common failsafes include: providing a return to launch/home function (RTL/
RTH) at the press of a button, creating a predefined geofence defined by specific heightor distance, which serves as a virtual boundary for a particular drone flight, ensuringthat it doesn’t stray too far or too high, or low battery warnings which trigger specific
events such as RTL/RTH or an immediate landing. Other events that can trigger failsafes
include loss of radio control and loss of GNSS.
For remote sensing applications, an important functionality is the triggering of a sensor
at predefined times or locations, giving the pilot the ability to control data collection intime and space. Autopilots such as the Pixhawk, and variations upon this flight controller, allow for this. There are also autopilots utilising a Raspberry Pi (RPi) via an arduino
hat, such as that made by Emlid4. These utilise PX4/Ardupilot firmware, and allow for
the use of the typical array of sensors. These also allow the utilisation of the RPi as an
onboard Linux computer to control sensors, collect, and process data in ways that aren’t
possible from any other autopilot in this price range.

5.3

Batteries

From smartphones and laptops, to hybrid or fully electric cars and trucks, and all the way
up to home and industrial energy storage, lithium-ion (Li-ion) and more recently, lithium-polymer (Li-Po or LiPo) batteries have been key to their successes and evolution, andthe same is true of drones. The power to weight ratio offered by new generation batteries
have made electronics more mobile, but also, because of this same energy density andthe chemical compounds involved, these need to be treated with caution and recycled
responsibly. Although LiPo batteries are generally safe (Wang et al., 2012), mishandling,misuse or accidents with lithium batteries can have unintended consequences that aren’teasy to deal with, such as unexpected combustion that cannot be extinguished withwater. There are a number of precautionary measures that can be taken to lessen therisk of serious accidents allowing an operator to safely utilise lithium batteries, which we
discuss in the following sections.

5.3.1

Safety of LiPos

The most commonly used battery type within drones is the Lithium Polymer battery(LiPo). Some LiPo batteries, such as those manufactured by DJI or 3DR, are considered
to be “smart”, whereby the charge and discharge rates, and current status are monitoredby the battery itself so the battery health can be relayed back to the drone and pilot. Some
batteries, including the Parrot Anafi, discharge automatically after a period ofinactivity. The majority of LiPo batteries however, do not have these features, but thebasic principles of LiPo batteries apply to all.
Voltage (V) is an important indicator to be aware of and can be used to trigger a failsafe
automated drone response. Each cell in a LiPo battery is rated at 3.7 V (its nominal voltage) and a given storage capacity rated in amp-hours (Ah), or more frequently with drone
batteries, milliamp-hours (mAh – note, there are a 1000 mAh in 1 Ah). The amp-hours
rating indicates the number of amps that can be drawn constantly to provide power for
one hour. These individual cells are combined into packs, either in series or parallel(sometimes both) to produce desired power outputs. These combinations are labelledon the LiPO battery packs, with an ‘S’ representing the number of cells in ‘series’ or ‘P’

4https://emlid.com/

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DRONES FOR CONSERVATION

to indicate the number of packs in ‘parallel’, followed by the total nominal voltage. The
other indicator of note on LiPo batteries are the ‘C’ ratings, whereby C is the multiplierof the mAh capacity in the LiPo to indicate the maximum number of amps available at asafe constant discharge. To recap with an example; a 3S1P 3,000 mAh 20 C battery = a
11.1 V single pack 3,000 mAh battery, that can provide 3A (1C) of power for one hour, or
can provide a maximum constant safe discharge of 60 A (20C).
Thermal runaway, or spontaneous heating is the major safety concern with lithium
batteries and can be caused by a number of different catalysts, including overcharge/
discharge, physical damage, overheating or short circuits (Wang et al., 2012). Lithium
batteries that undergo thermal runaway can give off toxic gases, cause fires and, in somecases, explode. Lithium battery fires are also difficult to extinguish at source due to thepotential for the battery to generate its own oxygen and hydrogen.
When powering drone launches, all LiPo batteries will experience some form of ‘batterysag’ which will typically display as a voltage drop of approximately 0.2–0.3 V per cell (S).
For safe flying, it is recommended to only fly until you have a minimum charge of 3.5 V
per cell, at which point the drone should have already, or be very close to having, landed.
Under load during flight, and even more so with multi-rotors, once a LiPo has dropped
to 3.4 V per cell, voltage undergoes a relatively rapid exponential drop in power that canvery quickly lead to a crash or thermal runaway. In smart LiPo battery systems the drone
will often have failsafes set up, so that once the battery reaches a low threshold, the controller will beep to notify the pilot of the need to bring the drone to land (25% remaining
energy) or will automatically return to home and land (10% remaining energy).

Always check your
LiPo battery for signsof damage before While LiPo batteries can quickly become unsafe if improperly cared for, being acutely
every flight to prevent aware of any early warning signs of damage or overuse can drastically reduce potential
dangerous accidents. accidents. Knowing when a battery should be deemed unusable is paramount to their
Indications a battery safe function. An early warning sign of a LiPo becoming unsafe is when it becomes ‘puffy’is no longer flight safe or distorted from its original shape. Internally, the battery has begun to produce gas,include puffing expanding the container and should be retired from use. Any visible signs of damage
or distortion. to the exterior of the battery should also be considered as having rendered the battery
unusable and, in the event of an accident or crash with a drone, even without puffing orvisible damage, a LiPo battery should be treated as unusable until it has been thoroughly
checked for signs of deterioration or visible puffing.

There are a myriad of ‘proper disposal’ techniques discussed in forums and blog posts on
the internet, should a battery be deemed unusable. The only advice that can be given hereis that of following the manufacturer’s guidelines and, where possible, finding an appropriate, local e-waste or hazardous waste disposal facility. If working in a location where
this is not viable, research the disposal method prior to undertaking fieldwork. Decide on
an appropriate solution should the disposal need arise and prepare for the worst. Make
sure you are fully aware of the potential hazards involved with any given method andhave adequate mitigation protocols in place. Disposal methods are an individual choice
and responsibility falls upon every drone user. Some municipal recycling centres will
accept LiPO batteries for recycling.

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5.3.2

Always read the LiPo
manufacturer’s instructions and guidance for theproper use, anddisposal of batteries.

For batteries that aren’t‘smart’ i.e do not assess theircharge and discharge, it isworth considering keeping abattery logbook, recording
each charge/discharge andlog flight amp values andflight times.
When the fully charged
amp rate starts to diminish,
or flight times shorten,
consider replacing thebattery.

Charge, discharge and battery life

If not using a manufacturer supplied charger, it is important to use one that has a specific function for LiPo batteries, including a dedicated ‘balancing’ port that can handle
the equivalent number of cells as your LiPo (S value). Typical charging rates should notexceed 1C of the battery and so using our example from the previous section, that battery
should be charged at a maximum of 3 A and to a maximum of 12.6 V. Most LiPo battery
chargers will automatically control the maximum voltage of a given battery based on the
S value input into the charger, but the input amperage can normally be adjusted, and it ispossible to charge at a rate lower than 1C which may help to extend the life of the battery.
In addition to the general advice above, always read the LiPo manufacturer’s instructions
and guidance as that should always supersede what is written here or elsewhere. Impropercharging can lead to charge/discharge internally between cells (balance), or over/undercharge of the entire pack, and both can subsequently lead to thermal runaway, and potentially, a drone crash.
Whilst LiPo batteries are considered to have a relatively long lifespan (Scrosati andGarche, 2010), typically lasting 300 charge cycles, this lifespan is based upon usage where
the draw on the battery is low relative to its capacity (≤ 1C). In drone operation, this israrely achievable, and batteries undergo stress that decreases their lifespan, with somelasting as few as 20 or 30 flights. Because LiPos possess a higher comparative C rating to
the drone’s amp draw, they tend to be less stressed and hence exhibit longer lifespans. For
example, if your drone typically draws 15 A during normal flight, and your two 3000 mAhbatteries are rated at 10 C and 20 C respectively, then it is likely that your 20 C battery will
have a longer lifespan. For batteries that aren’t ‘smart’, it is worth considering keeping abattery logbook, recording each charge/discharge/flight, logging amp values and flighttimes. As the fully charged amp rate starts to diminish, or the flight times start to shorten,
then it is likely that the battery is becoming worn and replacement should be considered.

Figure 21: A 3DR Solo drone is equipped with several cameras and extra batteries,
which are checked before every flight. © University of Exeter DroneLabDRONES FOR CONSERVATION

54

5.3.3
If you are travelling by
airplane with your drone it
is vital that you check therules about carrying drone
batteries with your airline,
prior to travel.
There are strong restrictions
preventing check-in or
carry-on for Lithium-based
batteries.

Travelling with LiPo batteries

Travelling with LiPo batteries has become more complicated in recent years with mostairlines tightening restrictions on the transport of these batteries. These restrictions don’t
just apply to airline passengers either, many postal and delivery services are now limiting
the size of batteries they will transport or ship. As a result, it may be necessary to use more
specialist certified services for transport of hazardous materials, although these can be relatively costly. Airlines now specify the total energy density a passenger is allowed to carry,with this normally being described in watt-hour (Wh). Wh can be calculated by multiplying the number of volts in the battery by the Ah of the battery (if working in mAh divideby 1000). These guidelines are provided by most national aviation authorities but always
check with your airline for exact Wh and individual item limits before travel.
It is important to remember that when travelling with LiPo batteries, they should always
be charged/discharged to the nominal voltage level, stored in LiPo safe bags at all times
and where applicable, terminal ends should be protected with electrically insulated tapeor covers. We recommend carrying an official letter detailing the contents of your LiPO
bags with you whilst travelling to defuse confrontations at security.

Figure 22: This custom-built drone has 6 rotors to carry an SLR camera for professional
photography. © Chris Hunkeler/Creative Commons

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5.3.4

Summary•

Always transport and store batteries in a LiPo safe bag or fire-safe locker.

•

Keep batteries cool and never leave in direct sunlight. Room temperature isnormally sufficient but in hotter climates, a cooler, shaded space may be required.

•

LiPo cells have an absolute minimum discharge level of 3 V per cell andnever should never be charged beyond 4.2 V per cell.

•

Check battery voltages before charging/discharging to ensure within normal
limits.

•If possible, charge/discharge batteries within a LiPo safe bag but ensure that thebattery is visible to check for excessive heat build-up, puffing or smoke.

•

Charge away from any flammable materials or liquids, and where possible,
on top of non-combustible surfaces such as concrete or marble.

•

Do not leave charging/discharging batteries unattended.

•

Keep a class D fire extinguisher at hand. In remote locations or where this is not
feasible, a bucket of sand. Never try to extinguish with water.

•

Do not leave batteries fully charged for extended periods of time. If a battery has
been charged for use but is not utilised within a few days, it is best to discharge tostorage capacity.

•

Allow batteries to cool before charging (post flight) or after charging (pre-flight).

•

Another useful option for transportation, charge/discharge and storage (alongside
or in conjunction with LiPo safe bags) is an ex-military ammunition box. It isessential to drill holes into the ammunition box though so as to allow any gas
build up to dissipate in the unlikely event of thermal runaway.

•

Finally, NEVER post, dispatch or carry a damaged, puffy, or a suspected defective
LiPo on an airplane (and be cautious if transporting by any other means).

•

For transportation on commercial airliners, check the service providers regula­tions with regards to LiPo batteries. The Federal Aviation Authority in the US givea good example of the general rules5 but these will vary from country to country
and airline to airline.

5	https://www.faa.gov/about/office_org/headquarters_offices/ash/ash_programs/hazmat/passenger_info/
media/Airline_passengers_and_batteries.pdf

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5.4

Motors, Propellers and Electronic Speed Controllers

Too much payload leading to an underpowered aircraft can quickly lead to an accident.
Understanding of electronic speed controllers (ESCs), brushless motors and propellers
and their relationship to the basic principles of drone flight can help minimize the chanceof accidents prior to take-off.
At their most basic, ESCs, motors and propellers use the chemical energy of a LiPo battery as electricity, and then convert it into mechanical energy and finally thrust. The ESC
is responsible for regulating the power supplied to the motor(s). The motor(s) in turn,provide(s) a combination of speed and torque to the propeller(s), and these then generate
the thrust required for flight.
In order to calculate required thrust, you must consider the type of drone you are using,as the calculations vary for each machine. In comparison to fixed-wing drones, calculating the thrust required for multi-rotors to fly is fairly straightforward: a sum greater than
100% of the aircraft’s mass is needed for flight, meaning that whatever an aircraft weighs,
you’ll need motors and propellers capable of generating thrust greater than that of themachine’s weight. A general principal for any multi-rotor is that it will ideally create
twice the mass in thrust at 100% throttle. For example, a multi-rotor that weighs 2 kg will
generate 4 kg of thrust at full throttle. Representing an overall thrust to weight ratio of
2:1. It is essentially aviation by brute force.
For fixed-wing drones, the amount of thrust required to achieve flight is based upon watts(W) per unit of mass (e.g. kg) and can vary de­pen­ding on the airframe and type of flying
style required. Factors such as lift generated from the wings, and the drag of airframe play
an important role. It’s also important to be aware that the thrust required to sustain flightwill likely be lower than that required for take-off. Fixed-wing drones with an autopilot incontrol of the flight are incredibly stable and almost static in their flight patterns by comparison to the nuanced control of manual flying. However, they tend to be heavier thanmulti-rotors, and are likely to require a bungee/catapult or hand launch to take off. Hand
launching requires a co-pilot to physically throw the drone into the air, whereas a bungee/
catapult take-off is achieved by using a thick elastic cord to fire the drone forward. If notusing an off-the-shelf drone, much of the more detailed information available for selecting
the correct motor can be confusing. Airframe kits that come “ready-to-fly” (RTF), or “plugand-play” (PNP) are considered “off-the-shelf” and can simplify the selection process. If
it’s an “almost ready-to-fly” (ARF), then follow the manufacturers guidelines but be awareof the additional weight of any extra electronics or sensors that need to be added.

5.4.1

Motors

While there are two distinct types of motors – brushed and brushless – brushed motors
are an older technology that are now obsolete within the drone community, with brushless motors now the preferred and most commonly used. Brushless motors all follow anomenclature system that denotes their name, size, and the revolution per minute pervolt (Kv) rating that allows for quick selection based on a manufacturer’s guidelines. The
first 4 numbers are essentially two pairs of measurements in millimetres, the first pairis for the motor diameter, but can either be the full external diameter (outside edges of
the rotor, the moving part of the motor) or the diameter of the internal stator (the fixedpart of the motor). The second pair of numbers indicate the height of the motor, again
either of the internal stator, or the external rotor. Next is the Kv rating (not the same as
kV – kilovolts), which is the motor rpm (revolutions per minute) per volt applied, (i.e. itsconstant velocity). The Kv rating is also an indicator of the size of propeller a motor can

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spin. Higher Kv ratings will spin a smaller propeller, faster, a lower Kv rating will spin alarger propeller, slower. It is essentially a torque versus speed offset.
To select the right motor and propeller combination it is important to know a set of
information about the motor. Manufacturers will also provide details on the minimum/
maximum input voltage, maximum amps and with more recent changes for multi-rotors, specification sheets to advise on the various battery voltage, motor and propeller
combinations and their subsequent power demands and outputs in amps (A), watts(W), and thrust in grams (g). This can be a significant help when trying to select theright motor and propeller combinations, but most motors specifically designed for fixed
wing airframes forgo the additional data on thrust (g). They normally provide only
battery voltage and propeller combination with the subsequent amps and watts. It is also
becoming more common for multi-rotor motors to be specified as either CW (clockwise)or CCW (counter-clockwise) as multi-rotors rely on equal paired numbers of each (2CW
and 2CCW for a quadcopter). If this information is missing, then the motor can easily bemade to spin in either direction simply by swapping the positive and negative connections to the ESC (it is also possible to specify the direction of turn within the firmware of
the ESC but is more complex than just switching the positive and negative connections).

5.4.2

Propellers

Propellers are a type of airfoil, not unlike wings on an aircraft except that they are notstatic in relationship to the body of the aircraft. When a propeller turns/spins, it’s airfoil
is designed to screw the blade through the air, with changes in air pressure generated by
the propeller providing the thrust. It is akin to using a corkscrew to open a bottle of wine,or inserting a screw into wood – a propeller “screws” into the air. With multi-rotors, it isalso possible to gain some transitional lift from the propellers when in forward motion,
whereby the propellers act as both a fixed wing and a propeller at the same time. If you
notice your multi-rotor drawing less power than expected at a given forward velocity, it’s
likely to be transitional lift (a sweet spot for efficiency).
As with the motors on a multi-rotor, propellers are required in equal paired numbersof CW and CCW and need to be fitted to their corresponding motor (CW propeller onto
CW motor). In fixed-wing terminology, the CCW is known as either a normal or tractor
and the CW as either reverse or pusher. Propellers are sized in inches, with the overall
diameter proceeding the blade pitch. Essentially, the blade pitch is the distance the propeller will screw through the air with each revolution. As thrust and lift both relate to theoverall surface area of the propeller, and propeller efficiency increases with size, it could
be tempting to always choose large, high-pitched propellers. However, both an increasein pitch and an increase in the diameter of the propeller will increase the required torqueand subsequent amps drawn (and relates to the motor Kv mentioned earlier) and apoorly matched set up can quickly overheat and burn out components.
Generally, multi-rotors tend to utilise pitches from 8 to 12 cm, with lower pitches allowing for quicker acceleration, and then rely on increasing the diameter of the propellers
to generate any extra thrust required. They have also evolved to include a flatter, wider
blade profile. Fixed wing drones are the opposite, with pitch playing a bigger role because
they equate to a greater top speed, which is more important in the forward velocity
needed by the aircraft.

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58

Plastic propellers
are cheaper, but more
flexible. Wooden pro­pellers provide a moreenvironmentally friendly
option with the added bonusof being quieter in operation

Propellers come in a range of materials including plastic, carbon fibre, plastic/carbon
fibre hybrids and wood. Weight of the propeller generally has a marginal impact on
power draw, whereas the material’s flexibility can have a greater impact. Propeller tips
that are too flexible can bend upwards at high speeds because most of the thrust/lift isgenerated towards the tip, causing a difference in force at either end of the blade that will
deform the propeller. If this happens then there will be a reduction in propeller efficiency
and may – in the case of overburdened multi-rotors – result in instability and ultimately,a crash. Propellers are one of the components most likely to be damaged during generaluse. As such, because they are less expensive, users may be tempted to use plastic propellers, but because of their flexibility and non-recyclable properties, other propeller types,
especially wooden, should be considered as an environmentally friendly option.
For most drone users, drone noise is of limited importance, but when utilizing drones
for conservation or ecological research purposes, especially where animal welfare is con­cerned, it is an important consideration, as drones can disturb or stress the subjects ofinterest (see section 3.6). Lowering the Kv of the motor and choosing to fly with larger
propellers with a stiffer material can reduce the overall noise generated by the aircraft.

Always check propellers
for damage such as
nicks, chips or cracks
before flight, andreplace if needed.

In addition to propeller size and material, balance is also an important consideration when
discussing propellers at large. Propeller balance can affect flight efficiency and stability, as
well as the quality of data recorded by onboard sensors. Improperly balanced propellers
will be less efficient in flight, and will also result in vibrations that can nega­tively affect sensor-gathered data. One of the reasons DJI has become so successful is due to the stabilityof their camera gimbals. However, where sensors aren’t mounted on a gimbal, vibration
remains an issue. At a minimum, propellers should always be cleaned and checked fordamage such as nicks or chips. Light scratches can be counter balanced using a propellerbalancer or light sanding, the application of masking tape or light brushes of correction
fluid. If a propeller is chipped or cracked then it needs to be replaced.

Figure 22: Ortho-mosaic and DSM over an illegally burned forest in a Brazilian Amazon
protected area. © Felipe Spina Avino/WWF Brazil

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5.4.3

Electronic Speed Controllers (ESCs)

ESCs function as a regulatory system that is initiated by the autopilot as a mechanism tocontrol the amount of energy the motor is supplied from the battery. The autopilot tells
the ESC how much energy is required by the motor, in turn, the ESC regulates the flow ofenergy from the battery to the motor accordingly.
Although uncommon, some motor and ESC combinations don’t work well together
and, where possible, users constructing their own drones should select an ESC that’s
recommended by the motor manufacturer. A good rule of thumb when choosing an
ESC, whether for a multi-rotor or a fixed wing, is to have an ESC that has an amp rating
at least 20% higher than what is expected to be required by the motor and propeller
combination. ESCs can generate a lot of heat when under load and excessive heat can bedamaging, leading to an ESC failure and possible crash.
ESCs can be classified into one of two types based on whether they possess a battery
eliminator circuit (BEC) or not. BECs allow for the ESC to power other electronics inconjunction with motor(s). ESCs without a BEC are referred to as optoisolators, or OPTO
for short, and cannot power additional electronics. For fixed-wing drones, having an ESC
with an incorporated BEC can reduce the amount of electronics required because the BEC
can provide a stable 5 V to the servo rail of the flight controller, and can also act as flightcontroller backup power supply. The same is possible with multi-rotors, but only one ESC
should be used as a BEC, with the others having the power supply pins removed from theconnector to the flight controller. This is necessary to avoid interfering signals from eachof the 4 BEC power supplies to the flight controller causing what is known as a “brown out”
(confusion within the system caused by competing signals), which can result in issues withthe motor’s power delivery. The downside to this is that one ESC will be working harderand generating more heat than the others, and subsequently is at greater risk of failure. If
one ESC fails on a quadcopter, there’s a much higher likelihood of a crash than with a hex/
octocopter or fixed wing. As such, choosing a dedicated 4in1 ESC for a quadcopter can bea good choice as these have smaller footprints, are easy to incorporate, and typically comewith a dedicated BEC that has less of an impact on the ESC’s workload. Post installation of
ESCs and before the first test flight of a new drone, it is very important to follow the flightcontroller guidelines for the calibration of ESCs. This is to ensure that the signal processing
and power delivery are synchronised so that all motors are working correctly.

5.4.4

Radio control (Rx/Tx) and telemetryRadio control and telemetry facilitate radio communications between the pilot, drone, andco-pilot, making them an essential system within any drone design. Off-the-shelf drones
typically come with systems that use the Wi-Fi frequencies of 2.4 or 5.8 GHz (gigahertz).
These are excellent for carrying multiple data streams such as high definition video, telemetry, and control all within a wide bandwidth on a single frequency. However, it’s important
to note that these Wi-Fi systems are not ubiquitous amongst all drone set-ups. In most use
cases when flying across areas of 1–100 ha, 2.4 or 5.8 GHz should provide sufficient range
for continuous connectivity, but in areas with potential obstacles (e.g. trees) that could
interfere with signals, these frequencies may not be optimal. The right frequency for a given
situation depends on balancing transmission distance, obstacles, and the type/volume ofdata needing to be transmitted. Higher frequencies, such as those used by Wi-Fi, are able
to transmit a high volume of data across short distances, but are not particularly suited topenetrating obstacles, whereas lower frequencies are able to transmit across long distancesand penetrate obstacles, but are limited in the amount of data they can transmit. Common
alternative frequencies options are 433, 868, 915 MHz (megahertz) and 1.2/1.3 GHz.

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60

Radio control and video systems consist of two units, the transmitter (Tx) and theonboard receiver (Rx). The frequencies of 433, 868, and 915 MHz, and 2.4 (5.8 is lessuseful here because of its limited range) GHz, are typically used for control and telemetry, whereas the 1.2/1.3 and 2.4 or 5.8 GHz are used for video transmission. Most readyto use handheld radio control units now come as standard with 2.4 GHz Tx’s and Rx’s but
many can be swapped out for long range systems (LRS) that utilise 433, 868 or 915 MHz
and can potentially control drones over 10’s or even 100’s of kilometres.
Importantly, the use of radio frequencies is governed by national and governmental laws,
and this must be given due constraint when purchasing a drone for use in a particularcountry. A couple of important points with regards to radio frequencies are that nationallaws govern their use. This includes bands and associated power supply (see Chapter
7). The frequency of 2.4 GHz is a common and widely used band due to Wi-Fi infrastructure, and while this is unlikely to be an issue when operating in remote areas, it is still
important to switch off other sources of Wi-Fi on mobile phones, in some cases activating
flight mode, to avoid interference from Wi-Fi enabled sensors being carried by the drone
such as GoPro cameras. Signals can easily become swamped and a drone control can belost due to these competing signals. If trying to utilise a video relay system or FPV, it isimportant to use control and tele­metry frequencies that are different to the video relay.
Because all of these frequencies are sine waves, using 2.4 for control and 1.2 for video will
result in interference when the two sine waves synchronise.
Table 2: Summary of different drone capabilities

Fixed Wing

Multi-Rotor

BalloonKite

Takeoff/landing space

Large

Small

small

mediumEndurance

30–60 mins

20 mins

2–4 dayshours

Payload0.5–2 kg

0.5–3 kg

0.3 kg

0.5 kg

AgilityMediumHigh

Low/Low

Low

Manoeuvrability

MediumHigh

Low/Low

Low

Autonomy

Full

Full

CameraCamera61

DRONES FOR CONSERVATIONEMPOWERING TRADITIONAL COMMUNITIES AND FRONT-LINE STAFF
TO USE DRONES FOR CONSERVATION.
Felipe Spina Avino, WWF-Brazil

Felipe Spina Avino is a Brazilian Conservation Biologist who has worked in SouthAmerica, Africa, and Europe. Currently, he leads the work on Conservation Technologies at the WWF-Brazil Science team, where has been building the capacity of
local communities, Rangers, and PA managers to use Conservation Technologies,
including drones, to monitor and protect their landscapes.
Felipe and colleagues have been promoting drones as a powerful way to involve traditional communities, combining traditional knowledge, technology, and science to assist in monitoring and combating deforestation andfires in protected areas in the Amazon and Cerrado.

Key advice for conservation practitioners:
1.

Before you decide to buy a drone, learn from others through research, for example, the review by PanequeGálvez et al. on Small Drones for Community-Based Forest Monitoring, and the online platforms: Wildlabs
and ConservationDrones.

2.

To be more effective, especially in larger areas, drones should be used in combination with other technologies, such as satellite data, to provide near-real-time data on deforestation and forest-fires.
3.	If you are working with community
members, it is critical to engage them inall project phases to enable them to work
independently to protect and monitor
their territories. Ensure they are skilled
in all project aspects, including flying
and maintenance skills, the capacity toeffectively gather data, and analyze it.

Further information:
Ferreira, Manuel Eduardo et al. “Zoning
the Fire-Risk in Protected Areas in Brazil
with Drones: A Study Case for the Brasília
National Park.” IGARSS 2019 - 2019 IEEE
International Geoscience and Remote
Sensing Symposium (2019): 9097-9100.
DOI:10.1109/IGARSS.2019.8900421

Training traditional communities andPA’s managers to use drones to assist with
Cerrado conservation and Non-timber
forest products sustainable management.
© Paulo Henrique-Funatura/WWF-Brazil

The Little Wild Horse & Bell Canyon is a remarkable hiking area in the desert landscapeof Green River, Utah, USA. © Michael Tuszynski/Unsplash.com

63

DRONES FOR CONSERVATIONDRONE SENSORS
6.1

Introduction

There are a wide variety of sensors available for drones and, while it’s not possible tocover them all here in detail, we review some of the typical constraints and considerations when trying to incorporate an after-market sensor into a drone system. The following points cover some of these major considerations:•

Understanding how the data need to be collected and whether the sensor canfacilitate this is important. Blindly purchasing a sensor to do so without these
considerations can quickly lead to owning a device that can’t deliver and will likely
not meet expectations. The user must carefully consider whether a sensor needs
to be triggered remotely. If not, the sensor may need to be triggered to record dataprior to take-off, which will require additional data storage capabilities and theediting of extra data, post flight. Alternatively, some sensors will provide a timelapse or intervalometer function via internal firmware/software (allowing users to
capture data at set time intervals), while others won’t. In some cases behaviour
can be modified via firmware hacks such as the Canon Hack Development Kit6.
Some sensors may also be activated via a hot-shoe (the metal contact point foundon top of some sensors) or a dedicated control port (via a cable connecting to thesensor), or possibly even via dedicated servo acting as a finger (a physical mechanism used to push the shutter button), all of which can be controlled via theautopilot.

•

Sensor sensitivity relative to the flight characteristics of the drone is worthy of
consideration to assure high quality data are collected. With more sensitive sensors, the vibrations produced from the motors and propellers on drones can distort images or introduce aberrations into the data. Velocity or unstable flight cancause issues and is why gimbals or other forms of stabilisation are so important
for recording video from drones, or using cameras with adjustable shutter speeds.

•

For most types of sensor, weight isn’t as much of a factor as it used to be. In recent
years, an increasing number of devices have been adapted for drone use (mainly
through miniaturisation of parts), but the overall physical size of the sensor stillneeds to be considered. If the sensor cannot be housed securely on, within or
onboard the drone platform, then it should not be used.

•

Cost is also a factor as many sensors may be more valuable than the drone itself,
and as discussed in Chapter 3, choosing the sensor may determine which drone touse, simply from a sensor-protection standpoint.

•

One final point is the use of position data (e.g. from an onboard GPS or GNSS)
and whether it needs to be used or merged into the data collected from the sensor,
for example via a camera that incorporates latitude and longitude in the EXIF
data of collected photos. Again, some may come with simple GNSS built in thatis sufficient, but in cases where GNSS is needed, working out how that can beachieved may play a role in which sensor to choose.

6

http://chdk.wikia.com/wiki/CHDK

6.2

Overview of drone sensors

Drones can be equipped and customized with a variety of sensor types, depending on thedata requirements for your survey or study area, and the weight capacity of your drone.
Here we showcase the different types of drone sensors, their costs, advantages and somecommon examples. The references provide more specific applications and uses.

MULTISPECTRAL — LOW-COST

MULTISPECTRAL — FULL RADIOMETRIC

AGROCAM

PARROT SEQUOIAExample Models

Agrocam, MAPIR Survey2

Example Models

Tetracam Mini-MCA, Parrot Sequoia,
Micasense Altum

Typical Price Range€200–500

Typical Price Range€2,000–8,000

Typical Weight Range 50–150 g

Typical Weight Range 500–1,500 g

ExampleApplications

Plant health, landcover classification

ExampleApplications

Plant health, landcover classification

Notes

Usually flown in pairs or as part of an array

Notes

Full radiometric could allow for better
integration with other RS products

References

Koucká et al. 2018

References

Ahmed et al., 2017

OPTICAL — ACTION CAMERASOPTICAL — COMPACT CONSUMER GRADE CAMERASGOPRO HERO 3+

CANON S110

Example Models

GoPro,Yi Action Camera

Example Models

Ricoh GR II,
Canon S110

Typical Price Range€100–500

Typical Price Range€200–500

Typical Weight Range 100–150 g

Typical Weight Range 200–400 g

ExampleApplications

 ilming animal movements,
F
creating films, orthomosaics, point clouds

ExampleApplications

Orthomosaics, point clouds

Notes an provide live feed to pilot; beware of wideC
angle views which distort data

Notes

Look out for manual modes, RAW and inter­
valometers which will allow more flexibility

References

Ventura et al. 2016

References

Jensen & Mathews 2016

OPTICAL — SINGLE LENS REFLEX (SLR)OPTICAL — MOBILE PHONESNIKON D 700

SMARTPHONE

Example Models

Nikon D3000, Canon 5D

Example Models

iPhone, Android phones

Typical Price Range€400–3,000

Typical Price Range€50–500

Typical Weight Range 750 –1,500 g

Typical Weight Range 100–200 g

ExampleApplications

Orthomosaics, point clouds

ExampleApplications

Orthomosaics, point clouds

Notes

Tend to require larger drones to carry theheavier payload

Notes

Need to use an app to automatically collectsensor data

ReferencesHodgson et al. 2013

References

Anderson et al. 2016

HYPERSPECTRAL

LIGHT DETECTION AND RANGING (LIDAR)SENOP HSC-2

YELLOWSCAN VX-20

Example Models

Senop HSC-2,
Optronics Hyperspectral

Example Models

RIEGL VUX-1UAV, YellowScan Vx,
Velodyne puck

Typical Price Range>€30,000

Typical Price Range€6,000-€30,000

Typical Weight Range 600 g-1000 g

Typical Weight Range 1kg - 3.5 kg

ExampleApplications

Forestry, plant health, landcoverclassification

ExampleApplications

Point clouds

Notes

Can involve complex radiometric andgeometric processing

Notes

May not come with inbuilt inertial
measurement unit or GNSS

References

Nezami et al., 2020; senop.fi

References

www.yellowscan-lidar.com

THERMAL

FLIR VUE PRO
Example Models

FLIR Vue Pro

Typical Price Range€2000-€5000

Typical Weight Range 100–300g
ExampleApplications

 opulation counts, cryptic featureP
detection

Notes

Beware of differences between radiometricand relative measurements

References

Kays et al. 2018

67

DRONES FOR CONSERVATIONUAS4ECOLOGY: DRONES FOR ECOLOGICAL RESEARCH

Urs A. Treier & Signe Normand, Ecoinformatics & Biodiversity,
Aarhus University, Denmark.

Urs A. Treier and Signe Normand are ecologists using drone-based
remote sensing to address questions in ecology and conservation.
They are running the UAS4Ecology Lab founded and led by Signe
Normand and managed by Urs Treier.
They apply UAS technology to understand vegetation changes in Arctic environments under global change by
combining extensive ground-based sampling with information derived from drone-based remote sensing. Theyuse simple consumer-based cameras, multispectral sensor or LiDAR carried by rather light quad- or octocopters.
Besides documenting field sites before sampling, they aim to quantify vegetation cover, productivity, and othersite-specific parameters that can be derived from the point-clouds, spectral information or ultra-high spatial
resolution. Drones provide the link between the highly valued field-based observations, and the large-scale earth
observations from satellites, ultimately allowing to up-scale information important for nature conservation andmanagement. Applying drones in Arctic environments is challenging. Harsh conditions and remote field sites
only reachable by helicopter, boat and foot demand robust, ultra-light, and modular equipment. Furthermore,when spending longer periods of time at a remote field camp they must produce power with solar panels torecharge batteries. Even though the drone industry has developed quickly in recent years, new solutions need to
be engineered and optimized for specific needs.

Key advice for the new drone scientist:
1.

Make your data collection as easy, simple, light, and cheap as possible - be question driven. Consider theobjective and hypothesis, data collection and processing, and results before starting your drone endeavour.

2.

Reference and standardise your drone data with independent ground control, ground truth and reflectancedata, especially if your aim is monitoring or change detection.

Further information:
https://twitter.com/UAS4Ecology© Urs. A. TrierFixed-wing drones are being used in Malaysia to monitor orangutan nests. Using a drone
is not only cost-effective, but more accurate than surveys from the ground or helicopter.
© K. Yoganand/WWF-Malaysia

69

DRONES FOR CONSERVATIONFLIGHT PLANNING AND OPERATIONS
7.1

Introduction

When planning drone flights, it is very important that drone operators consider thecomplex volumetric ‘airspace’ within which flight operations will occur. Knowing therules of this airspace is an essential part of becoming a drone pilot, and for countries
with national regulations, commercial drone pilots must sit examinations to prove thatthey know and understand these basic rules. For scientific researchers, or those working
within non-profit organisations, many countries have no requirement for pilots to obtaina special license from the aviation authorities since research-type flights in remote areas
are often classified separately to those undertaken for commercial operations. However,keep in mind licensing is rapidly changing, and familiarizing oneself with the following
basic information about airspace is essential for drone operations.
Understanding the capabilities of drones when operated in specific modes is also critical,
as these factors and settings will define the drone’s mobility, and the pilot’s control of theaircraft within the airspace. With increased availability of drone technology worldwide,users must be aware that there are a wide variety of legislative responses that individual
governments have implemented to control, or police, drone use. Being aware of thesevariations in national policy is critical, since in some countries, or areas, the legislation
will completely preclude drone use. This chapter provides a relatively brief, but critical
overview of these key issues, framing them for the conservation practitioner, concluding
with some key recommendations for ‘best practice’.

7.2

Airspace

Airspace should actually be considered as ‘air volume’. Airspace is a broad term thatdefines the complex invisible volumetric infrastructure that controls aircraft movementsin the atmosphere above our heads. Airspace globally is generally classified into volumetric blocks labelled with the letters ‘A’ to ‘G’. These volumetric zones vary in their level ofuse from one country to another, but include two important extremes of airspace:•

Class A (very tightly controlled: reserved for high speed jets and for ‘instrument
flight rules’ flights)•

Class G (uncontrolled: where aircraft must only follow simple rules)

In between classes A and G exist a series of other airspace zones, where pilots must maintain some level of radio contact with air traffic controllers. Airspace zones can extend
to different heights above ground level, depending on the types of operations that they
are designed to control. The best source of information on permanent air traffic zones
is a formal airspace map, which can be obtained from national civil aviation authorities– but note, these can be changed regularly, so users should consult the most up-to-date
information sources. Temporary air traffic zones can be set up to support certain typesof military civilian operations, and these tend to use a ‘NOTAM’ (notice to airmen (sic))route. Information about NOTAMs can be obtained online7 (Figure 24) – and the maps
shown also include permanent NOTAMs as well as temporary ones. Temporary NOTAMs
can include activities as diverse as military exercises, air shows, parachute jumps, firework displays and the presence of cranes extending into useable airspace.
7

https://notaminfo.com/ukmap,
https://skyvector.com/

DRONES FOR CONSERVATION

70

Figure 24: Example NOTAM map for the south-west United States on September 9,2020. NOTAMS in red and purple are restricted UAV airspace, due to military or otherplanned activities. Circles contain information denoting other airspace restriction tocertain heights above ground level.

It pays to think of these airspace designations volumetrically as a series of conical segments extending towards the upper atmosphere, as often there will be a series of concentric airspace designations extending outwards from major airports at different heights toallow for holding patterns and ascent/descent trajectories for large jets (Figure 25).

Class AFL 60018,000 MSL

Class E

14,500 MSL

Class BClass CClass D
700 AGL
Nontowered
AirportClass G

1,200 AGLClass GClass G

Figure 25: The complex volumetry “airspace” designations that broadly apply globally.
AGL = above ground level. FL = flight level (= height above ground level/100).
MSL = mean sea level

71

DRONES FOR CONSERVATION

For the most part, this user guide relates to the use of lightweight (<7 kg) drones, whichthemselves have operational limits related to battery life and restricted operational distance from pilot (imposed by radio control, wi-fi or visual line of sight limits). Also, giventhat it is illegal to operate drones within close proximity of major airports (and a terrible
idea to do so), and that most key conservation and ecology priority areas are situated far
from such infrastructures, we assume that such drones will mainly be operating withinclass G airspace (Garrett and Anderson, 2018). If we follow the UK Civil Aviation Authority Guidance (which is common to many other countries with drone regulations
in place), we find that the following rules of flight apply:
As a general rule, all drones
must fly within line of sightof the operator, and below
120 m.

The aircraft must stay within line of sight of the operator, and must not fly above
400 ft (120 m) from the ground level at take-off point. The maximum distancefor a single line-of-sight flight is 500 m from the pilot in command.
“Although operators of drones weighing 7 kg or less are not required to have thepermission of Air Traffic Control (even when flying within controlled airspace orwithin an aerodrome traffic zone), the Air Navigation Order requires that any person in
charge of a small drone may only fly the aircraft if reasonably satisfied that theflight can safely be made; and must maintain direct, unaided visual contact
with the aircraft”8Further, the responsibility “lies with the operator to determine if the area he (sic)has chosen to fly in is suitable”
Importantly, for drones equipped with cameras – those who do not have an additional
permission from the CAA, are “restricted to remaining at least 150 metres fromcongested areas or any organised, open-air assembly of more than
1,000 people. Drone operators must not fly camera fitted drones within adistance of 50 metres of any person, vessel, vehicle or structure that is
not under the control of the person in charge of the said aircraft (during take-off
and landing this distance may be reduced to 30 metres). This means that each flightwill carry a ground ‘footprint’ below the aircraft, within which there should be no
uninvolved members of the public.”
The term ‘bringing under control of the pilot’ is ambiguous, and cannot be interpreted
as simply requiring ‘notification’, since a person notified of your flight and potentiallyinterfering with it may not be under your control. If you cannot keep your drone morethan 50 m from subjects (volumetrically), you should not fly. Furthermore, any images
captured that compromise the privacy of non-consensual people should be deleted fromthe camera memory immediately after landing and never shared.

8

https://www.caa.co.uk/Consumers/Unmanned-aircraft/Our-role/Airspace-restrictions-for-unmanned-aircraft-and-drones/

72

DRONES FOR CONSERVATION

These rules are provided by civil aviation authorities around the world, an example fromSingapore shown in Figure 26. Importantly, the requirement to fly within ‘visual flightrules’ where the drone is always within the pilot’s line of sight is very pertinent to thoseflying small drones – the smaller the drone, the shorter the distance from the pilot(vertically or horizontally) that the pilot will lose sight of the aircraft, so the smaller thearea that can be surveyed per-flight.

Figure 26: Drone recommendations from the civil aviation authority of Singapore© Civil Aviation Authority of Singapore

73

DRONES FOR CONSERVATIONIn the UK, there is now a mobile phone application called ‘NATS assist’ which isexpressly designed for drone users. It is free to download and provides pilots with upto-date NOTAM information for their current location. It can also be used to raise
NOTAMs – so that once a pilot arrives at a site, they can drop a pin and enter a few
details that are then released as a temporary NOTAM to notify other air users of thedrone operation. Figure 27 shows a screenshot from this app, with the blue dot as thelocation of the user. Airspace restrictions are shown as yellow or red circles. In the USA,
B4UFLY9 is an app that checks for local flight restrictions and permissions around a
selected location.
Perhaps the best advice we can provide on airspace is that pilots should both check airspace prior to, (desk-based, and in situ) and during flights, and then make every effort to
notify other users of their intended flight operations, no matter how low the flights will be,
and even if short in duration. In Class G airspace, any air user can enter and fly throughthe volume using visual flight rules, which means that these uncongested zones are often
the places where military forces may perform unexpected low flight operations or practicemissions, or emergency aircraft such as helicopters will operate. For these reasons a goodsuggestion is to also make a courtesy phone call to any near-by air traffic control towers to
notify them of your location, time window of operations, maximum flight height and typeof aircraft. As long-term operators of drones we can say that information is power – airtraffic operators would rather know that you are there, they do not have the powers to stop
you from flying and they can notify other air users of your presence.

Figure 27: Left: Screenshot from the NATS-Assist app on 20 December 2018, in the
UK. The blue dot shows the drone operator’s location, and the coloured circular areas arethose places where airspace restrictions exist. Using this app, users can raise NOTAMs
for drone operations. Right: Screenshots from the B4UFLY app.

9

https://www.faa.gov/uas/recreational_fliers/where_can_i_fly/b4ufly/

DRONES FOR CONSERVATION

74

7.3

Flight modes

The increasing number of drones on the market means that a full digest of the variationsin flight modes available is impossible. However, we have summarised the major typesof flights that can be operated from many consumer drones on the market in Table 3.
These settings apply to multi-rotors for the most part, but some can also be used with
fixed wing systems.
Table 3: A summary of operational modes for most lightweight consumer-grade drones

MODE

FIXED WING
OR COPTER?

WHAT IT DOES

WHEN TO USE IT

Stabilised or‘positioning’mode, also
called hoveror loiter

CopterAll drone’s sensors (including GPS) will be
active, ensuring self-stabilisation of the dronein the air. If the pilot lets go of the controller’s
sticks, the aircraft should stop and hover overa fixed position. Flight can then be controlled in
x,y,z directions by manual control on the radio
controller. For some DJI drones this function
includes automatic obstacle avoidance

For manual surveys, reconnaissance,
following individuals, targeting specificareas or sampling things like whale
sputum (see case study page 33)

Attitudehold or‘ATTI’ (A)
mode

Both

This mode holds the drone at a fixed altitude,
but can drift in x,y. This mode can kick in if GPS
hold is lost during stabilised flight. The pilot is incontrol of all other commands

This is a sub-standard control compared
to stabilised mode, but it can be useful forsurveying complex areas, or remaining
above tree canopy, if an experienced pilot
is in charge. Best avoided for beginners.

Sport mode

CopterThis is a relatively new option available on
many DJI drones. It uses GPS for positioning but
disables forward and downward vision systems
so there is no obstacle avoidance capability. The
sensitivity on the controls is enhanced in ATTI
(attitude mode) making the drone responsive topilot input compared to stabilised modeThis is a faster velocity mode designed
to give pilots a thrill ride, and not ideal
for surveying. Images captured in thismode are likely to be blurry. It may only
be useful if you need to get your drone
somewhere fast, or bring it back to alanding spot quickly in the event of an
emergency.

GPSwaypoint
mode

Both

This mode allows the pilot to pre-plan a waypointed route that the drone will follow. An
automatic take off and landing point can be
defined, and the drone can be programmed
to complete a fully autonomous flight. Camera
parameters can sometimes be used to define
the flight settings on the basis of desired
overlap and sidelap (e.g. for photogrammetricpurposes). The pilot must be able to take controlof the aircraft and interrupt the autonomous
flight in the event of an emergency

This is a widely used method for capturing
reproducible survey data for mapping,orthomosaic generation or structure-frommotion photogrammetric workflows.

Fully manual

Both

Many of the drone’s sensors are disabled andthe pilot must control everything. In reality mostdrones will not permit full manual control since
it is risky for all but most advanced pilots

Probably best avoided unless you are a
professional drone racer or have extensive
experience.

Return tolaunch (RTL)or Return toHome (RTH)

BothThis is a common feature of most GPScontrolled consumer drones. The take-off site isstored in the drone’s memory and the drone canreturn to hover over this position if RTL mode istriggered. RTH returns to a pre-defined locationor the loaction of pilot/controller

This is useful at the end of a GPS-guided
survey, or if the battery becomes drained
and a rapid landing sequence is required.
The drone will usually fly back quickly to a
RTL or RTH position at a pre-determinedheightAir brake

Copters

This is a recent feature in some multi-rotor
drones. It allows the pilot to interrupt a GPSwaypoint mission and pauses the drone in
mid-air by starting ATTI or stabilised mode. The
GPS waypoint route can be re-started from thepaused position

This is very useful if something strange
happens mid-survey. E.g. an obstacle isencountered, wind speed suddenly picks
up, a bird shows interest in the drone or amob of crows appear overhead. It can givethe pilot some time to decide on whether
it is safe to continue with the survey or RTL
or RTH to land.

75

DRONES FOR CONSERVATION

7.4

Navigation and accuracy

GPS capabilities on board drones are typically basic consumer-grade systems, whichmeans that users can expect spatial accuracy in x,y,z to be typically +/-2-5 m or as low
as +/- 10 m. For this reason, the positional accuracy of your drone in volumetric spaceis at best, approximate within these limits. For these reasons it is essential for the pilot(and preferably a co-pilot or spotter) to maintain eye contact with the drone as it flies inorder to be able to take prompt action if the drone comes closer than one would wish toa feature (e.g. building). Some drone companies give full access to the flight logs (such as
3DR or self-built), others make accessing this information more difficult (DJI), but even
if you retrieve these flight logs they will only provide a general idea of position withinthose abovementioned accuracy limits.
For improved accuracy of the location of the drone, one needs on-board high accuracy
GPS, known also as real-time-kinematic (RTK) GPS. This is where the drone will communicate with a base station whose position is known to within a few cm in x,y,z. The
differential correction to this base station will allow a much more precise location of thedrone to be determined. Whilst most consumer drone systems do not include RTK capabilities, in Spring 2019, DJI released a Phantom 4 RTK-capable system, although the costremains relatively high (at the time of writing the cost for the drone plus base station was
in excess of €8,000). PPK (post-processing kinematic) GNSS solutions are also available
which deliver similar accuracy to RTK, but require post-processing of flight logs.
Without RTK capabilities on the drone, geo-positional information about features within
the scene can only be obtained via independent reference to ground control points
deployed within the scene and referenced using a differential GNSS system (Figure 28
shows such a methodology in operation). For many applications this level of accuracy will
not be necessary – such detail is only needed if the absolute position of objects on the
Earth’s surface is needed. For some applications hand-held GPS survey of such markers
can provide useful validation of drone products, for example, markers can be used toconstrain the location of pixels within a geospatial workflow (e.g. orthomosaic generation) or to check the quality of resultant builds relative to an independent measurement(e.g. compare the location of a pixel in the model build vs. its position measured on the
ground).

Figure 28: The use of a ground-based RTK survey system includes a base station (left)
and ground control points reference markers deployed within the survey area (right).

DRONES FOR CONSERVATION

76

7.5

Legal issues and permits

All countries have some form of legislation covering aviation practice and airspace management, however there is variability in the strength of legislation as it applies to different types of drone operations. Table 4, from DeBell et al., (2015), evidences the diversityof drone legislation across some regions of the world.
Table 4: UAV industry and legislation for the major economic regions of the world. From DeBell et al. (2015), but note
this information was published several years prior to the publication of this WWF report, so some information may now
have changed.

REGULATED?

COMMERCIALUAV FLIGHTSPERMITTED?

HOBBYISTUAV FLIGHTSPERMITTED?

Y

Y

Y

Y

2 kg defines “small” UAV(including payload);
license required.

CanadaYYYY

UAV flights permissible
under license.

China

Y

Nb

Yb

Y

Europea

Y

Yc

Y

Y

India

Y

N

N

?

MexicoY

NYY

Liberal attitudes to UAV use(Garcia 2013)

UAV RELATEDINDUSTRY
Australia

OTHER NOTES

Variation in definitions acrossdifferent EU member statessee (Silverburn 2013)

d

USA

Y

Y

N

Y

Commercial use currently
under revision y the FAA.
No fly zones implemented incertain regions.

BrazilY

YYYCurrently a complete banon commercial UAV use

Note: data collated in January 2015.
aEurope has been included as a single entity due to its unified trade and legislation.
b
China appears to allow operation by authorization at a provincial or town planning level but has nothing in place at a national level.
c	While there are overarching EU guidelines, it is also stated that each member state is responsible for applying their own law
relating to UAV use.
d	There are competitions involving UAVs and plenty of hobbyists flying, but regulation relating to hobby pursuits has been difficult
to find.

To provide an example of the diversity of international regulations: in the UK, researchor recreational flights with small drones weighing less than 7 kg TOW require an online
exam, drone registration with a unique identifier10 (see Figure 26). Research pilots
should also obtain permission from the landowner from whose land the drone will takeoff and land prior to flights. In the USA, all pilots must be registered with the Federal
Aviation Authority and hold a current drone pilot’s license11. To obtain this license pilots
undertake a theory and practical test, preceded by several days of classroom teaching.
The USA also requires all drone users to register with the FAA and fit their drones with a10https://www.caa.co.uk/Consumers/Unmanned-aircraft-and-drones/

11

https://www.faa.gov/uas/77

DRONES FOR CONSERVATION

Some websites to check fordrone regulations:
Australia:
https://www.casa.gov.au/
dronesUSA:
https://faadronezone.faa.
gov/

license plate and ID. Similar rules are being implemented in Europe12. Permits may also
be required depending on the location of surveys, with tighter controls on federal land
and in National Parks, for example. Much like the fast-paced technological changes (e.g.
B-VLOS, swarm flying and, detect and avoidance technology (Chapter 11)), the associated regulation is struggling to keep apace of drone developments, therefore it is criticalthat all pilots themselves obtain timely information on the rules within their operating
country prior to flying.

7.6

We provide here a set of key recommendations and actions that drone pilots can follow tohelp ensure that operational problems do not arise.
•

If travelling, be mindful that large drones attract attention at customs and you
should always carry appropriate official paperwork with you to ensure smooth
entry into the country. This also includes receipt of purchase, insurance infor­
mation and import permits. Smaller drones or fold-up models concealed withincarry-on bags attract less attention, but still require proof of ownership and permits where needed. Do not transport a drone battery (typically LiPo) in checked
luggage (see Section 5.3.1).

•

Check the drone laws for the operating country prior to flights.

•

If a licence to fly a drone is required, leave plenty of time to fill paperwork andobtain permits, since this can sometimes be a lengthy process, depending on the
country.

•

Notify, and where necessary, obtain permission from landowner/s prior tooperations.

•Notify other airspace users of your intention to fly, operational flight plans andon completion of your survey, repeat the same.

•

Use geofences within your flight planning software to ensure that you do not
encroach into unauthorised airspace in both height and lateral bounds.

•

Be aware of privacy issues and remove all images of non-consenting people
from your image sets.

•

If you encounter resistance or conflicts during your drone operations,land your drone before discussing.

•

Carry all your paperwork with you to site.

•

Wherever possible, when you fly take a co-pilot or a spotter along with you towatch out for aerial and terrestrial hazards and manage inquisitive bystanders
while you focus on flying.

Europe:https://www.easa.europa.
eu/domains/civil-drones/
naa
Drone bans:
https://uavcoach.com/
drone-bans/
Compiled list of regulations
by country and state:https://uavcoach.com/
drone-laws/

Best practice12

https://www.easa.europa.eu/domains/civil-drones-rpas

A polar bear leaps across the ice in Nunavut, Canada. The 2018 winner of the“Drone Awards Photographer of the Year” © Florian Ledoux/Drone Awards/Art Photo Travel

79

DRONES FOR CONSERVATIONDRONE DATA
8.1

The drone’s niche

Drones unlock the potential to capture data at finer spatial and temporal resolutions
than satellite or airborne remote sensing platforms offer. Information about a particular environment, individual, or group of organisms can be collected in greater detail,meaning smaller features can be detected, comprising a larger number of pixels at finer
resolution. Drone-based data can also be collected more frequently (i.e. surveys could be
conducted at varying frequencies, from daily to multiple times or specific times of day).
To help describe the drone’s niche, the following sections will compare proximal sensing
tech­nology to existing remote sensing platforms, such as satellites and light aircraft, andalso to in situ monitoring techniques.
Some satellite data sources:
Copernicus Sentinel Hub:
https://www.sentinel-hub.
com/
NASA Landsat Science:https://landsat.gsfc.nasa.
gov/
Planet:https://www.planet.com/
MAXAR (DigitalGlobe):
https://discover.digitalglobe.
com/
Airbus Geostore:
https://www.intelligenceairbusds.com/geostore/

Satellite platforms currently offer a broad suite of data products which can be of use toscientists, environmental managers and conservation practitioners alike (Pettorelli et al.,2018b). Some satellite programs (e.g. Landsat and Copernicus) offer freely available data,
whereas commercial operators of higher resolution imagers/sensors (MAXAR, Planet,
Airbus) charge for access to their data. Satellite platforms carry a variety of sensors that
operate both actively and passively, sensing across the electromagnetic spectrum. For
example, some platforms such as Worldview-3 or Sentinel-2 carry multispectral sensors,
spanning the visible part of the spectrum, as well as a near-infrared band (Ferreira etal., 2016). Some sensors offer spectral capabilities in the near-, short-wave and thermal
infrared part of the spectrum. Information captured within these individual bands (orcombinations of them) can provide rich information about various characteristics of the
Earth’s surface (Pettorelli et al., 2018b). While a wide range of sensors exist, they are
pre-determined by the organisations which design and run the satellite systems. It may
be the case that particular sensors do not collect sufficient information to answer someresearch questions.
The freely available data archive of the Landsat satellite program makes it a powerful tool
for analysis on multi-decadal scales, for example investigating habitat change in responseto storm events over time (Douglas et al., 2018). The ability to investigate change oversuch large temporal extents makes satellite based remote sensing useful for research,
management and conservation purposes. Satellite data can be acquired on temporal resolutions of single days or weeks. With the regular addition of new systems and constellations, revisit times (i.e. how often images over a given area will be captured) are being
significantly reduced (e.g. Sentinel platforms are expected to deliver revisits of between
1 and 6 days (Berger et al., 2012). Regardless of the expected revisit times, the orbits ofmost satellite image capture are timed to occur at the same time of day, every day, anduseable data cannot always be guaranteed. For optical sensors cloud cover and atmospheric haze is a significant obstacle, either obscuring features, or creating altered brightness in areas of cloud or cloud shadow (Zhu and Woodcock, 2012). Furthermore, otherfeatures such as the presence of water in intertidal areas or shadows at the beginning or
end of daylight can reduce the quality of, or invalidate, the data acquired. The inability toadjust the time of data acquisition from satellite platforms is significant drawback of thistype of remote sensing technique. This leads to potential uneven sampling regimes andgaps in datasets.

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DRONES FOR CONSERVATION

Airborne platforms can be used to collect remote sensing data at specific times andplaces. The advantages of using light aircraft include the finer spatial resolution data andbetter control over the timing of data collection. Therefore, dynamic processes can be
captured during times that are most suited to the application in question. Airborne campaigns can be undertaken at low tide states when intertidal environments are exposed
and not obscured by the water column, for example, or animal behaviours or movements
captured when they are most likely to occur. Airborne surveys can also cover significant
areas, e.g. 10–100 km2, which is suitable for studies at the landscape or regional scales.
The major drawbacks of airborne operations however are mainly linked to their logistical complexity. They require a team of trained individuals (e.g. pilots, sensor operators)
to undertake successful flights, as well as a suitable aircraft, fuel, infrastructure and theassociated authorisations. These factors make it an expensive and somewhat exclusive
form of data capture, where it is limited to those that have the necessary resources tolaunch such a campaign.
In situ monitoring with specialized sensors such as terrestrial laser scanners (TLS) offers
very fine-grained data measuring structural and physical variables of environmental
features at a specific point in time. Examples of TLS applications within the environmental sciences include sand dunes (Feagin et al., 2012), cliff faces (Westoby et al., 2018) andthe monitoring of landscape processes such as river catchment development (Kociuba etal., 2014). The data outputs from this technology are typically ultra-fine resolution, dense
point clouds, which if used effectively can produce a 3D representation of the landscapeor features. Compared to drones, this is a very useful approach, given the situations
where drones are unable to capture data of features hidden from the nadir viewpoint.
However, this technology remains expensive (laser scanners can cost over €20,000) andare cumbersome, making it difficult to transport in the field, while the spatial coverage islimited to relatively small range (up to 1 ha per scan). This immobility could be detrimental to data acquisition, especially if time-limited by a specific process, environmental
conditions or the presence of an individual or group of individuals. Other in situ remotesensing approaches for ecological and environmental monitoring include ground-based
photography, such as movement triggered camera traps or time-lapse photography. As
with the other techniques highlighted here, each of these are beneficial when used in particular circumstances (e.g. time-lapse to monitor the evolution of shorelines over time),
but the lack of perspective, due to the ground-based positioning, limits the spatial extent
at which data can be captured.
contrast to the aforementioned approaches, drone technology democratises theDrones are a self-service In
remote sensing workflow – allowing individuals to collect data when they want anddata capture method, where they want. Drones can be described as a self-service data capture methodology,
allowing the user allowing the user to time the acquisition of data when it is best suited in relation to envito collect information ronmental conditions or the position of features of interest (such as landscape structures
when it is best suited of organisms). For example, within intertidal coastal zones, the timing of data acquisition
to their research. is crucial, due to the presence of water during the tidal cycle. Scenarios such as these
are well suited to drone-based data collection, and it has been demonstrated throughthe mapping of spatial heterogeneity within intertidal seagrass meadows (Duffy et al.,2018b).

81

DRONES FOR CONSERVATION

Figure 29: A drone-based survey of gharials in Nepal, a critically endangered crocodile species known for theirsignificant length. © G. Jung Thapa/WWF-Nepal

Drones are also highly flexible, both in their design and the types of sensors that can be
attached to them (see Chapter 5 and Chapter 6). This means that drone users cancapture remote sensing data in the formats they require, containing the information mostuse­ful to their desired applications or research questions. As has been shown within the
spotlight features in this report, the types of sensors are wide ranging, spanning opticaland sonic data capture, as well as the acquisition of biological samples from the naturalenvironment. The flexibility in airframe design also opens opportunities to attach various
types of sensors and execute flights in a variety of manners (e.g. hovering to collect dataat the same location over a defined period of time, or flying at a faster speed to image thelargest area as possible in a single flight).

8.2

Available software and costs

Software associated with drone-based data collection and processing can broadly be
split into three categories (when considering data from optical sensors).
• mission planning software• ground station software• data processing and analysis software

8.2.1

Mission planning software

Mission planning software is used to set up the drone system and plan flights (if automated with the use of GPS onboard the drone). This software can also be used to change
parameters on the drone, such as default speeds, sensor calibration onboard the autopilot and program default behaviours (e.g. return-to-launch routines), and failsafes. Some
autopilot systems, and associated software, will even let the user manipulate how the
hardware performs (such as power output to the motors) or logging information from
specific sensors inside the autopilot.

DRONES FOR CONSERVATION

82

8.2.2

Ground station software

Ground station operations which control the drone in flight are often run on a phoneor tablet, but can also be executed on a laptop computer (depending on the softwareand associated autopilot). The key features of these software packages are to aid in the
launch, landing and operation of the drone whilst airborne. In some cases, these features
are bundled with mission planning capabilities into one software package. Some of thesesoftware packages are drone manufacturer specific, some work for multiple models, andthey are a mixture of free and paid for (Table 5). Examples include ground station Pro(for DJI models) and Solex for the 3DR Solo quadcopter. Autopilots in custom madedrones will often have compatible ground station software available, although it’s best
to check this with the manufacturer/supplier to be sure.

Table 5: Available third-party drone planning software and apps

NAME

OPERATING SYSTEMDESCRIPTIONWEBSITE

B4UFLY

Android and iOS

The Federal Aviation Adminis­tration (FAA)
has produced this app to make it very
easy to know where in the US you can,and cannot, fly your drone.

https://kittyhawk.io/b4ufly/

AirmapAndroid and iOS

A comprehensive flight planning app that
also includes regulations for more than
20 countries. Can be used to program DJI
drones.

www.airmap.com

DroneDeploy

Android and iOS

Flight planning app and cloud-processing
platform for 3D models and vegetation
indices (NDVI). Also offers an enterpriseplatform

www.dronedeploy.com

Mission Planner

Mac and Windows

Computer based open source planningsoftware and image geo-positioning.
Oriented towards custom built drones
running Ardupilot software

www.ardupilot.org/planner

DJI goAndroid and iOS

Planning software designed for all models
of DJI drones

www.dji.com/de/goapp

LitschiAndroid and iOS

Open source mission planning software
designed for DJI droneswww.flylitchi.com

Maps made easy

Web and iOS

Web system for cloud processing of drone
data, and an integrated planning app for
DJI drones

www.mapsmadeeasy.com

83

DRONES FOR CONSERVATION

8.2.3

Data processing and analysis software

The most common way to process and obtain tangible outputs from optical and multispectral data captured from drones is by using photogrammetric approaches – namely
Structure-from-Motion Multi-View Stereo (SfM-MVS). Software offering this sort ofprocessing typically allows the user to output a variety of spatial products produced fromtheir inputs. These include, but are not limited to, orthomosaics, 3-dimensional models,digital elevation models and point clouds. Each of these detailed datasets can be usedeither individually or in tandem for a variety of ecological and environmental applications. See Chapter 3 for examples of drone data usage in conservation and ecology.
Photogrammetry software packages are highly varied, and each is unique in terms of thefeatures that it offers. Care­ful consideration is required before choosing which software
package to use for pro­cess­ing your drone data. Many of the proprietary programs offer afree trial for a limited period of time. This may serve as a good to test to see if your particular processing needs can be met with it. Table 6 shows a selection of typically used
free and commercial software packages. The software used to process the data is rarely
able to perform remote sensing or spatial analyses e.g. for image classification or topographic analysis. Users must export products (e.g. orthomosaics, surface models) fromthese processing softwares and undertake such higher level processing elsewhere. There
are an infinite number of possible workflows for post-hoc handling of geospatial datasets,
including open source toolkits such as R and QGIS.

Table 6: A non-exhaustive list of photogrammetry software packages. Adapted from Forsmoo et al. (2019)

NAME

SOURCEGUIDE PRICE

Agisoft Metashapewww.agisoft.com$179 (standard)$3499 (professional)

Pix4D

www.pix4d.com$4400 dollars (standard)$240 monthly

3DFlow Zephyr Pro

www.3dflow.net/3df-zephyr-pro-3d-models-from-photos/

Free to $4300 depending on
version/features

MICMAC

github.com/micmacIGN/micmac

Free

GRAPHOSgithub.com/itos3d/GRAPHOSFreeAutodesk Recap

www.autodesk.com/products/recap/overview$310 yearly

ESRI Drone2Map

www.esri.com/en-us/arcgis/products/drone2map/overview$2500 yearly

Photomodeler Premium

www.photomodeler.com$995 (standard) $49 monthly

RealityCapture

www.capturingreality.com

Pay per input pricing
options available

OpenDroneMap

www.opendronemap.org

Free

DroneDeploy

www.dronedeploy.com$99 per month

DRONES FOR CONSERVATION

84

8.3

Data processing approaches

For data processing approaches, the planning, flying procedure and the research goal, will
impact what type of method, or processing pipeline, will be required to achieve the desired
result. For some applications minimal or no processing may be required, as individual
images may provide the information required. But where multiple images, or multiple
types of data need to be combined, processing may become slightly more complex.
Starting with our first example, it is easily possible to capture one hectare with a single
image utilising a wide-angled lens on a camera or smartphone flown at ~100 m altitude.
If this image was captured with complimentary position data (e.g. from GPS or GNSS),
the latitude and longitude could be inserted via the Exif information of the image, oradded via a GIS software, which may be enough to provide a simple base map on a local
scale. However, one of the key benefits of using proximal sensing technology is the larger
extent that can be covered with a single mission where overlapping aerial photographs,
or other images, are captured in sequence as the drone moves across the area.
Should larger areas need to be covered, or 2.5D data is required (surface or volumetricdata), if there is a need to fly at a lower altitude or flying above an object of height (forexample flying at 100 m altitude but over a tree canopy of 40 m height), then multiple
images may need to be “stitched” together, or mosaicked, to produce the desired output.
The previous section highlighted SfM-MVS as one of the most popular ways to processdrone data of this type and there are a multitude of specialist software available that
perform the SfM-MVS process.
Some of the most popular software options include Agisoft Metashape (formerly Photoscan), Pix4D and DroneDeploy, all of which are commercial products; the latter two cases
also include cloud-based options. There are many other commercial options available13,
as well as an evolving open-source option: OpenDroneMap14 (see Section 8.2.3). There
are many examples in the literature that detail SfM workflows for mosaicking image dataobtained from proximal sensing platforms. The software packages listed above also often
provide tutorials and sample data. Furthermore, thorough descriptions of the technique’s
application in a variety of fields can be found in the literature (Burns et al., 2015, Smithet al., 2016, McDowall and Lynch, 2017).
Aside from the above, it is also useful to have a plan in place for the managed storage ofany data collected, for example flight logs and their associated images. If flying multiple
missions on a regular basis, it can be easy to either lose track of which flight log corresponds to which data set, or accidentally overwrite the autopilot with logs from more
recent missions. In addition, large capacity USB sticks or external hard drives are essential assets in the field, as data collected can quickly grow to the 10’s and possibly even100’s of GB.

13

https://geo-matching.com/photogrammetric-imagery-processing-software

14

https://www.opendronemap.org/

85

DRONES FOR CONSERVATION

MAPPING HABITATS OF THE GREAT BARRIER REEF
Karen Joyce, James Cook University

Karen is a remote sensing researcher and educator in Queensland,
Australia, who loves using satellites and drones to map, measure, andmonitor from above to help look after our environment.
Karen has been working on the Great Barrier Reef since the late 1990’s,
mapping the different corals, algae, and other underwater habitats. Initially she used a lot of satellite data to create maps, but now more and more is being done with drones. One of thebiggest challenges for mapping the reef is that the water gets in the way of being able to clearly see the coral. But
drones allow us to be flexible in terms of selecting the time to capture data to align with low tide to be able to see
the reef with less interference from the water column. Karen and colleagues have collected several years’ worth ofdrone data over the Heron Reef study site, so that they can now quantify changes that are occurring at very finespatial scales. This level of detail was only previously possible by conducting in-water surveys, which often have
limited coverage.

Key advice for conservation practitioners:
1.

Figure out the minimum characteristics of the data that you need to answer your question BEFORE you
select your geospatial tool. That is, don’t buy the drone until you are sure that it will serve your purpose!

2.

Remember to include software, data storage devices, and sufficient training (for software and drone flying)
into your drone start up budget.

Further
information:www.kejoyce.com

Drones are just one tool that
we use to unlock the habitat
secrets of the Great Barrier
Reef. We also use satellites tocover large areas, and in-water
surveys for calibration andvalidation.

The mangroves of Mahafaly, Southwester Madagascar are known for their exceptional
beauty, intactness and biodiversity, but are under increasing pressure from human activities.
© Martina Lippuner/WWF-Africa

87

DRONES FOR CONSERVATIONHIGHLIGHTS FROM WWF’S CONSERVATION ACTIVITIESAs the largest international conservation NGO on earth, the World Wide Fund for Nature(WWF) applies new technology to mitigate pressing environmental issues affecting
humans and wildlife alike. In addition to the more straightforward advantage of using
drones for anti-poaching, which started with the Wildlife Crime Technology Project15, theother applications of high quality, high spatial and temporal resolution data and remote
access in a variety of environments via drones, afford flexibility and innovation to meetthe needs of conservationists working to tackle issues such as climate change, sustainable
resource use, species conservation and the fight against wildlife crime.
Drones are facilitating better interactions between scientists and species. Observationand studies of wild animals in their habitats may involve dangerous access by scientists,or, on the contrary, distance is limited by laws and regulations, limiting the impacts ofthe studies. With advancing drone technology, including more powerful sensors, quiet
motors, scientists can get up close and personal (albeit while following best practices;
Chapter 7) with the species of interest. In Romania, WWF is using drones to deal withthe delicate nature of rehabilitating bear cubs (see case study on page 97). In the
Bear Orphanage in Romania, bear cubs must learn to forage for their food, and managers need to avoid as much human interaction as possible. A custom drone has beendeveloped to bring food to the animals and replicate their wild foraging activities, while
avoiding any human scents, not to mention saving time and effort on transport.
In the western US, a similar project using customized drones has been developed by
the US Fish and Wildlife Service and WWF-US to widely inoculate prairie dogs against
a deadly plague – which is meant to help endangered black footed ferrets, who prey onthem (Ditmer et al., 2015). An octocopter drone, outfitted with a customized hopper isused to drop vaccine-laden peanut-butter pellets into prairie dog burrows. The prairie
dogs eat them and then become immune to the sylvatic plague, a non-native disease they
have little natural immunity against. The vaccine delivery method by drone is as effective
and practical, and more affordable, than manual delivery via all-terrain vehicles, or vaccination of captive raised and released animals.
Nevertheless, drones may still have impacts on wildlife, and there is an increasing needfor assessment, and development of best practices, to minimize physiological stress fromscientific study via drones. The selection of fixed-wing drones, like those being used by
WWF-Malaysia to quantify orangutan nests in Borneo, are an improvement over helicopters, which are not only costly, but loud, disruptive and not very environmentally friendly.
In terms of mapping, surveying and collecting geo-spatial data, drones are multiplying theefficacy of conservation field campaigns. In eastern Africa, the use of drones is providing
extensive information on mangroves, which are swampy forests established in intertidal
zones and deep unstable mud, which are inaccessible, difficult and dangerous to access.
There is little one can do to avoid crocodiles, snakes and aggressive hippos, or virtually impenetrable tree stands, other than choose to not survey an area. These are common deterrents which tend to bias wetland field plots and measurements. In Tanzania,
WWF-Germany and WWF-Tanzania have deployed quadcopter drones outfitted with visible and infra-red cameras to assess mangrove forest stands. The drone data are being used

15 https://www.worldwildlife.org/projects/wildlife-crime-technology-project

DRONES FOR CONSERVATION88

to identify canopy species, as well as canopy density, heterogeneity, and at fine spatial
resolution, vegetation indices to assess forest health (Tian et al., 2017). Ultimately, thesesurveys provide the perfect dataset at intermediate scale between field plots and satellite,
and can be integrated into satellite workflows for biomass estimation, as in Navarro et al.
(2019) or applicable to forest health in the context of certification activities.16
Also in East Africa, WWF-Germany and WWF-Mozambique have used airborne drones
to assess underwater coral reef ecosystems, which are otherwise difficult to observe atlarge scales, requiring dive and snorkeling gear and methods, boats, all complicated bywater depth, tides, and currents. Some areas are often too dangerous or remote even toaccess, and a drone can easily overcome this, and in these environments is less hinderedby terrain or vegetation. The approach delivers fine spatial resolution geo-located images,
which can be used to identify benthic habitats and provide extensive field information for
calibrating and validating satellite-image derived maps (see figure). There are however,other elements to consider when surveying marine habitats, notably to reduce the effectsof sun glint on the ocean surface (Joyce et al., 2019).
The use of drones in conservation projects is also a powerful way to involve local communities. Between 2018 and 2019, WWF-Brazil trained more than 100 people including protected areas managers, traditional communities, as well as local associations, to increase
involvement and combine traditional knowledge with science to detect and prevent forest
fires and deforestation. There are similar efforts around the world as NGOs involve local
communities in monitoring and patrolling efforts, particularly in the context of reducing
emissions from deforestation and degradation (REDD+) projects (Paneque-Gálvez et al.,2014). Involving more people in data collection, while educating them in safety measures, best practices, and providing guides like this one, will ensure that conservation willcontinue to evolve and improve along with the dynamic drone technology we use.

Figure 30: Training indigenous groups in the Amazon forest to monitor fires anddeforestation with the help of drones. © WWF-Brazil/Osvaldo Gajardo
16

https://www.worldwildlife.org/stories/drones-provide-an-up-close-look-at-the-health-of-forests

89

DRONES FOR CONSERVATIONSURVEYING RIVER DOLPHINS IN THE AMAZON
Marcelo Oliveira, WWF-Brazil

Marcelo is a conservation biologist with 19 years of experience in protected areas
management and wildlife conservation projects in different biomes in Brazil. After
finishing the Master’s in Conservation Leadership at the University of Cambridge, hestarted his career in the Amazon working mainly on habitat connectivity, the links
between habitat and human health, and social engagement in conservation.
Quantifying abundance of wildlife is key for sound management and conservation.
Much effort has been invested into freshwater dolphin surveys in the Amazon basin.
However, river dimensions and complex logistics limit replication of such studies across the region. WWF evaluated the effectiveness of using Unmanned Aerial Vehicles (UAVs) for surveying two Amazon dolphin species,
tucuxi and pink dolphin, in tropical rivers. Compared to estimates derived from visual surveys, the use of UAVs
could provide a less expensive and more accurate estimate of Amazon River dolphins.

Key advice for conservation practitioners:
1.

Experienced pilots are a necessity. The small multi-rotor off-the-shelf UAVs were chosen because of vertical
take-off and landing capability required to operate from a boat in movement, and their stability in flight.
However, under strong wind situations, the take-off and landing operations were challenging.

2.

Follow well-defined operational protocols, including the best practice described in the literature (Hodgson
and Koh 2016), and ensure minimal disturbance to wildlife, and the safety of operators and researchers.

Further information:© Mauro Pimentel/AFP

Oliveira-da-Costa, M., Marmontel, M., Da-Rosa, D., Coelho, A., Wich, S., Mosquera-Guerra, F., & Trujillo,
F. (2019.). Effectiveness of unmanned aerial vehicles to detect Amazon dolphins. Oryx, 1-3. doi:10.1017/
S0030605319000279

The communal conservancy of Spitzkoppe, Namibia, empowers local communities with the rights
to manage and benefit from wildlife, strengthening rights, livelihoods and stewardship of theseunique landscapes. © Martina Lippuner/WWF-Africa

91

DRONES FOR CONSERVATIONTECHNOLOGICAL LIMITATIONS, CAVEATS AND
SOLUTIONS
10.1

Platform Limitations

Drone platforms can be divided into two types – multi-rotor and fixed wing (as describedin Chapter 5). There are some limitations shared by both types of airframe, as well someaircraft specific drawbacks. In this section we will deal with each in turn.

Multi-rotor platforms
are generally easier
to operate than
fixed-wing.

Fixed wing drones
may cover a greater
distance beyond
line-of-sight, but
not exclusively.
Check flight permissions.

Fixed wing drones are generally more challenging to operate than multi-rotor platforms. Firstly, they often require more space to land and take off, and a more involved
pilot or co-pilot for launch. Some larger fixed wings can require infrastructure such asa catapult or scaffold ramp for launch, whereas some can be launched with a bungee.
Small fixed wings such as the eBee or Parrot Disco can be launched by hand. For drones
that do require extra equipment, careful consideration is required as to whether it isfeasible to transport this extra kit to survey areas. Secondly, for landing, fixed wings
typically require open spaces where they can glide to the ground. This requirement is a
key consideration during flight planning. Also, landings can be rough, so designs that
protect sensors (e.g. by either embedding them in a recess within the fuselage or installing a servo activated cover plate) are recommended. Next, fixed wing drones generally fly
faster and remain constantly moving once in the air. This requires more experienced andconfident pilots that are comfortable with the notion that the drone cannot hover over a
position as multi-rotors can. Some autopilots may offer a loiter mode which instructs thedrone to circle at a given diameter from a GNSS-guided position, which leaves the drone
undertaking a predictable behaviour while the pilot makes their next decision. In relation
to obstacle avoidance and safe flying, the quick speeds and inability to hover require
more advanced piloting skills and quick reaction times. Due to their airframe design andtypically single motor setups, fixed wing drones are more sensitive to wind, especiallygusty conditions. This means that their operating range tends to be narrower (in termsof weather, wind speeds) than multi-rotors. Wind can also have more of an affect during
gridded survey flights, where the drones speed will be affected on ‘up-wind’ and ‘downwind’ legs. Survey design can alleviate this issue to a certain extent, by flying 90 degrees
to the prevailing wind direction. Finally, because fixed wings fly longer, they can operateover larger areas, which means they tend to be flown beyond the line of sight, meaningcertain legislative challenges may need to be overcome prior to flying see Chapter 7).
Multi-rotor platforms are easier to operate due to their ability to vertically take-off, land
and hover or loiter in a fixed position. The take-off and landing space required is muchsmaller, and for more advanced pilots can also be from a moving platform such as a boat.
However, they do have several limitations which need to be considered when planningtheir use for research or conservation purposes. Due to the multiple motors inherent intheir design, these types of drones use a lot more battery power during flight and therefore
have much shorter flight times than a typical fixed wing drone. This can limit the aerial
coverage in a single flight and require surveys to be split into multiple missions. Carefulplanning of flights, with the possibility of different landing locations to take-off, could aid
in covering greater areas in a shorter amount of time. Another drawback of multi-rotor
drones is the exposure of components to the elements. Self, or custom-built, multi-rotor
drones tend to have more wiring and electronics openly exposed on the frame. While thisis useful for maintenance and modification purposes, it also means that, along with the
motors, they are vulnerable to ingress from water (salt, fresh and rain), humidity, sand andDRONES FOR CONSERVATION

92

Multi-rotor platforms
are easier to operate
due to their ability
to vertically take-off,land and hover orloiter in a fixed position

dust particles (Duffy et al., 2018a). Some ‘off-the-shelf’ models, such as the DJI phantom,
have a plastic shell which helps protect most components from these environmental conditions. Furthermore, it is recommended to have spare components at all times to replace
any parts that have been damaged by exposure (e.g. rotors, batteries, propellers). Multi-rotor drones produce a loud buzzing noise from their motors. This can be disruptive or evenharmful to wildlife (see section 3.6), and is, therefore, a major limiting factor in survey
design and operations that involve the surveying of wildlife, or planned in environmentswith sensitive animals in close proximity. Also, if sensors such as microphones are being
used on the drone then (see case study, page 103), the noise from the motors needs tobe accounted for in sensor design, mounting and/or analysis. Noise is seen as one of the
key areas in which the consumer market can be advanced and, as a result, drone manufacturers are working on reducing it in newer versions of their products.

10.2

Sensor Limitations

Regardless of the type of sensor, the weight of the payload is a major limiting factor
when it comes to deciding what type of sensors to mount on board a drone platform.
The amount of thrust available from the on-board electric motors, size and design of
the airframe, will determine how much weight can be safely carried on-board a drone.
For commercially available platforms, this limit is usually stated by the manufacturer,
whereas for custom made platforms, some calculations will need to be made, given the
power of on-board motors. It is also important to note that, alongside the weight of thesensor itself, a mount or gimbal may also have to be considered to stabilize image capture. We advise that, prior to any actual survey flights with a new sensor configuration,
tests should be conducted with a ‘dummy’ weight (e.g. bags of rice) equal to the weight ofproposed sensors, so that the pilot can observe the performance of the drone without therisk of losing a valuable sensor should a crash occur.
When using a self-build drone where the sensor is not integrated, the biggest challenge iscreating a harmonious and reliable link between sensor and drone, or enabling a sensor/
payload to operate independently at desired times or time intervals. The most simple
solution is to operate a sensor autonomously, for example by using a camera with a built inintervalometer that takes photos at regular intervals without relying on any cues from the
autopilot. This can be achieved with cameras, such as the Ricoh GR II or GoPros, flashing firmware onto an SD card to increase the functionality of a camera (e.g. Canon Hack
Development Kit (CHDK) on Canon Powershot D30), or by using a cable to send pulses
from the autopilot to the sensor to trigger the shutter (e.g. Canon S110). Alternatives include
pre-determined triggers, linked to the autopilot and/or the Tx/Rx system operated by thepilot. This means that sensors can be triggered when certain criteria are met (e.g. distancetravelled, position in space, or sufficient overlap; e.g.(Anderson et al., 2016)), or by the pilot
remotely activating a switch on their controller/ground station. These types of links and setups are crucial for successful data capture with drones. Drone operators should ensure that
their sensors operate as desired in different scenarios, and that the link between platform
and sensor is reliable.
Consumer grade cameras have become a sensor of choice for many researchers and conservation practitioners due to their affordability, consistency and ease-of-use. To effectively be utilised on a drone platform, a few operational limitations must be overcome
or considered. Firstly, in ‘auto’ mode, many cameras will vary some, or all of, the shutter
speed, aperture and ISO settings between photos, in order to obtain a well exposed
photograph. While this tends to result in the creation of well exposed photos (especially
useful if weather conditions are variable), it means that the images are not as useful for93

DRONES FOR CONSERVATIONASSESSING MANGROVES IN THE RUFIJI DELTA, TANZANIA
Aurélie Shapiro, WWF-Germany

Aurélie is a remote sensing specialist for WWF in Germany, with an increasing interest in collecting data herself using commercial multi-rotor drones.
She has equipped a 3DR Solo drone with a visible and near-infrared camera,
enabling it to map high resolution vegetation indices in Tanzanian mangroves, as well as deriving 3-dimensional canopy structure. The mangrovesof the Rufiji Delta have a long history of human impact, resulting in changing species compositions, and degradation, which has resulted in an invasive liana establishment, which, in some cases, has completely covered theremaining trees. She uses drones to evaluate the composition and structure of the mangrove forests to determine
specific indicators which we can connect and monitor from satellite.

Key advice for conservation practitioners:
1.	The addition of a near-infrared camera has provided a whole new aspect of forest remote sensing via drone,with a richer dataset than visible information alone.
2.

Launching drones from boats can be a tricky endeavour, so we looked for sand banks exposed at low tide.

Further information:
https://arcg.is/0eXPOm

3D structure of a mangrove
stand created from aerial
photos taken from a 3DR
Solo drone. Darker reds
indicate higher canopy.

DRONES FOR CONSERVATION

94

remote sensing analysis or image mosaicking further down the line, because the exposure
varies in space and time. Two ways to help mitigate against this issue include fixing thecamera settings in a ‘manual’ mode, to ensure that settings such as shutter speed andaperture are kept consistent, and/or to enable the recording of RAW images alongsidecompressed image formats such as JPEGs. RAW files are digital negatives which allow
modifications to exposure post capture with fewer negative effects on image quality.
With a complimentary set of RAW images, modifications can be made to try and correct
exposure differences between images, which is beneficial when compositing images intoa mosaic. Lens focus is another issue which can result in a whole dataset being renderedunusable. Ideally, sensors with manual control of focal distance should be used for optical data capture. We recommend that the lens is focussed to infinity, as once at altitude,
everything at distance from the drone will be in focus.

Kites are capable ofproviding aerial data forenvironmental and ecological research purposes, Thermal sensors also require careful consideration prior to successful deployment forparticularly in inacces- data capture. Firstly, the resolution of image data produced by thermal sensors tends
sible or difficult environ- to be much lower than typical optical sensors. For example, the FLIR Vue Pro R has aments, or where weather sensor resolution of 336 × 256 pixels. Ultimately this means that features of interest for
may be too extreme for a which the sensor is intended to image need to be big enough in extent to be picked up
motor powered drone. by the sensor. Another limitation relates to the type of data being captured by the sensor– are the values fully radiometric (real calibrated measures of thermal emissivity) or
relative values. Again, depending on the application, relative values may suffice, but insome cases realistic measures of temperature may be required (for example checking thehealth of an animal). Fully calibrated sensors are also more expensive, with the FLIR Vue
Pro R costing ~50% more than the FLIR Vue Pro.

Figure 31: Humpback whales, honorable mention Wildlife category, 2018 Drone Awards.
© Anders Carlson/Drone Award/Art Photo Travel

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10.3

Legislative Limitations

Drone use has rapidly increased around the world, while the legislation has in places
struggled to keep pace. Fortunately, progress has been made with regards to obtaining
relevant permission from organisations such as the International Air Transport Association (IATA) and the United Nation’s International Civil Aviation Organisation (ICAO)
working together to formulate best practice and regulation guidelines for nation states,
alongside a database of existing regulations from around the world (see the ICAO safety
report17). It is important to remember that legal drone operations in one country may beillegal in another. Close attention should also be paid to the legality of flying, not just ina given country, but also in a given location. Flying in a rural environment might be OK,
but in a national park, or other designated land use, it may be prohibited.
Further legislative barriers to be aware of include those pertaining to privacy, data andradio frequencies. Capturing images of people or private property, and flying in proximity to government installations, should all be taken into consideration and the relevant
governing bodies should be contacted for advice. Even data laws should now be considered, with extreme examples, such as that recently passed in Tanzania, having the potential to land anyone collecting unauthorised data in prison18. Often overlooked is the fact
that, radio frequencies are used by a wide number of different sectors including telecommunications, transport, medical, industrial and scientific, therefore legislation aroundthese tends to be robust and can come with heavy penalties. Some frequencies such as
433MHz, 868MHz or 915MHz are country, or continent, specific based on the particular region’s use for telecommunications, whereas frequencies used for WiFi, 2.4GHz
and 5GHz, are globally ubiquitous and free to use. It is also worth noting that even if agiven frequency such as 2.4GHz can legally be used, there may still be restrictions on theamount of power allowed for transmission.

10.4

Alternative proximal sensing approaches

Kites, balloons and blimps offer an interesting twist on proximal sensing…they aretethered! Therefore, they are often considered piloted as opposed to unpiloted, presenting different methodological and legislative opportunities and challenges. It is useful toconsider these alternative proximal sensing platforms, especially when the aforementioned limitations with drone platforms and associated legislation can hinder your ability
to undertake proximal data capture. The following section will give an overview of eachof these three alternatives.
The technological boom (including lower cost, easily obtainable electronic components)that has helped fuel the uptake of drones has also benefitted other proximal platforms.
Kites in particular, are capable of providing aerial data for environmental and ecological research purposes, particularly in inaccessible or difficult environments, or where
weather that may be too extreme for a motored drone. For a review of this technology
and associated published work see Duffy and Anderson (2016). Kites are well suited toaerial operations in windy conditions that would otherwise be adverse for drones. Suitable levels of wind, combined with kites designed to be stable (e.g. kite aerial photography
or KAP kites), provide a useful platform for sensors which one can use to acquire data.
Kites are also relatively inexpensive, easy to transport and easy to operate. Compared tolightweight drones, kites excel in all of these areas, making them a feasible methodological choice when resources and logistical capabilities are restrictive (e.g. in remote polar
regions (Fraser et al., 1999)). As aforementioned, the tethered nature of kites can reduce17

https://www.icao.int/safety/Documents/ICAO_SR_2018_30082018.pdf

18

https://www.theeastafrican.co.ke/news/Tanzania-passes-new-draconian-data-law/-/2558/2667678/-/11ywry9z/-/index.html

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the level of legislative complexity when using them for data capture. This also makes
them a potentially safer alternative, especially when considering operations involving
animals. It is important to consider these alternative proximal sensing platforms as backups for drones. Kites fit this remit well due to their portability and ease-of-use.
Balloons and blimps are similar to kites, in that they can also be tethered. However, theyboth require helium (of differing volumes) in order to launch and achieve an airborne
position. This makes them stable platforms and ideal for data capture in fixed positions,or where variation in sensor position during a given survey is not required. They are also
sensitive to wind so have a restricted operational envelope, much like lightweight drones,
where high winds make them unsafe and likely unusable for the collection of high-quality
data. The need for helium does make them less portable and more logistically challenging
proximal sensing platforms. Although the tethered option could result in a reduction in
potential legislative hurdles, the risk of transporting and using compressed gas in thenatural environment adds complexity to operations using balloons and blimps.

Figure 32: The Skyrunner is a polish UAV Blimp made by sky&you. © Princo85/Wikimedia Commons

97

DRONES FOR CONSERVATIONBEAR CUBS: YOUR LUNCH IS IN THE AIR

Leonardo Bereczky and Alexandra Dumitrescu, WWF-Romania

Alexandra coordinates the individual fundraising efforts from WWF
Romania side to support the Bear Orphanage - the only facility in Europethat deals with orphan bear cubs and their rehabilition to be released in
the wild. Leonardo Berecsky built the center 15 years ago and handles thefacility, and has adapted a drone to fit the needs of the rehabilitation center.
The center is fully supported through charitable support.
Feeding the bears at the Bear Orphanage has always been a difficult process, in order to ensure that contact withhumans is kept to a minimum. Food has to be snuck in and hidden in different areas of the enclosed forest sothat the cubs have a similar experience to foraging in the wild.
This process has meant that Leonardo Bereczky had to carry large quantities of food on a regular basis up a steep
hill and wait for the right time in order to sneak in the enclosure undetected to provide the cubs with all they need.
Fortunately, this is no longer the case as Leonardo has made some modifications to a drone in order to fly in foodand release it from high above in the heart of the forest where the bears are located.* A plastic container with ametal lid and an electric remote release can carry up to 1.5 kilograms of food at over 100 km/h. The two kilometerround-trip is flown in just a few minutes, and the flying feeder is quickly ready for another round.
This device has great advantages. The cubs now have almost no contact with humans, nor do they pick up Leonardo’s scent, which would have lingered during the prior feeding process, meaning that the only Rehabilitation
Center for Orphan Bears in Europe is a major step closer to perfectly replicating life in the wild for the cubs andthus ensuring they have better chances of survival after they are released into the wild.
Feeding the cubs is one of the most important steps in the rehabilitation process. It’s not only what they are
given, or how much, but the when and how, which can be controlled via drone and is essential to limit the interference of humans into the bearcubs lives.

Key advice for conservation
practitioners:
1.	Invest in customized drones that can carry
multiple functions – not just imaging.
2.
be creative

Further information:
1.	Support the bear orphanage via WWF
Romania Patreon: www.patreon.com/
posts/wwf-starts-for-6724158
2.
More stories:
www.patreon.com/wwfromania
3.	And to view more about the bear cubs,
and the orphanage, follow WWF Romania
on YouTube.
* note that in some countries, releasing things from drones is illegal, so as always,
check national laws and regulations.

“Responsible Daddy the Gharial with Babies”, runner-up 2018 Drone Awards, Wildlife Category© Dhritiman Mukherjee/Drone Awards/Art Photo Travel

11

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FUTURE TRENDS AND POTENTIALS
Drone technology is advancing apace. Even in the time it has taken us to write thisreport, technology has changed and adapted. There are a great number of companies
and experts working on the next innovation, so here we highlight some of those potential
future advancements and frame them in the context of what they could deliver to conservation science.

11.1

First Person View (FPV) flying

First person view (FPV) technology, where pilots typically wear specialized FPV goggles,
allows the pilot to be ‘in the drone’ through a live video feed from a small camera on
board the aircraft. Within hobbyist drone groups there has already been an upsurge inthe use of FPV technology, particularly for drone racing, since FPV shortens the synapse
between the pilot’s hand controls and the motion of the aircraft, creating a more immersive flying experience. There are several potential benefits that could be gained withinconservation projects if FPV were to become widely employed:• For longer missions beyond visual line of sight (BVLOS), FPV offers a means of navigating airspace, should legislation allow.
• To capture information about specific target species FPV may be the only feasible
way to target sampling (either image-based or physical sampling (e.g. whale sputum
sampling, see case study page 33))
• For footage to inform conservation actions on the ground (e.g. mark/recapture typestudies), the immediacy of information gained through FPV facilitates more efficient
capture of target organisms by a ground team.
• FPV is a highly suitable to monitoring the safety of an area quickly – forexample, undertaking a rapid reconnaissance flight over an area that is to either
be surveyed on the ground, or from the air later on.
• FPV allows for rapid pilot intervention in the event of an unexpected hazard,
for example, emergent trees in a canopy that could not be seen during flightplanning, or the arrival of a curious raptor.

Figure 33: A visible RGB drone image (top) and the thermal vision appraoch for detecting hidden fawns in spring meadows, automatically detected by AI software and rescued
before mowing operations. © Adrian Meyer/FHNWDRONES FOR CONSERVATION

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11.2

Caged drones

As has been discussed in Chapter 7, ensuring the safety of pilots and other subjects(humans, animals or infrastructure) is paramount during drone operations. A major
cause of concern, and indeed perhaps the largest cause of injury from drones is thatpropeller sets that can lead to lacerations if flown dangerously. One innovation to mitigate the risk from drone propeller injuries, or damage, involves caging the aircraft insuch a way that flight is not interfered with. The Elios drone, for example was designedwith civil engineering inspections in mind – the cage allows it to navigate tight tunnels
and enclosed spaces without fear of damaging the drone or the infrastructure being
inspected. We suggest that beyond delivering enhanced safety functionality, these cages
open up new territories for ecologists and conservationists to survey. For example, caged
drones could deliver helpful data in underground ecosystems such as caves, or in confined areas where safety is paramount, such as in urban areas. Similarly, if flying in areasof challenging topography, or in highly structured ecosystems, the caged drone coulddeliver data where other drones cannot go.

Figure 34: Protective cage for
DJI Mavic 2. © Multinnov

11.3

Autonomous guidance

Most modern consumer-grade drone technology now contains autonomous guidance systems, particularly for automatic take-off and landing and detect-and-avoid capabilities.
For example, most DJI drones include, as standard, some form of obstacle avoidancetechnology, and automatic take-off and landing capabilities. In the future, the trend forincluding such capabilities is set to continue, since legislators place pressure on drone
manufacturers to hold some responsibility to ensure that customers cannot undertake
reckless flights, or accidentally cause damage to other people or property. Aside from thesafety case, these autonomous guidance systems may be useful, or unhelpful, to ecologists depending on the application area concerned. Of benefit is the greater reliability andreduced chance of accidental damage to hardware. However, in certain settings drone
pilots may find these control systems to be problematic – for example if data are requiredin close proximity to features such as trees the system over-ride could preclude data collection. In rough terrain, automatic landing can prove difficult if a flat surface cannot befound, and over-riding the autonomous control is harder in some systems than in others.

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In further developments, there are great innovations happening in research and commercial areas that exploit gesture-based control of drone platform movement – in somecases this can remove the need for a controller, since the drone responds to imagebased cues within the scene. This relies heavily on computer-vision based algorithms todetect desired subjects, and then gestures (arm movements, facial expressions) before
implementing pre-defined manoeuvres. This technology has been designed to anthropomorphise robotic technology to increase the usability of drones and remove the needfor complicated joystick-based control (Monajjemi et al., 2016).
New miniaturised hardware is now allowing near real-time image processing to takeplace on the drone in near real-time, meaning that drones can, for the first time, be
responsive in human timescales. The machine learning algorithms that have driven
this advancement hold great potential within conservation fields – for example, themethod of allowing a waving subject to be identified, and followed, could also be tuned
to respond to natural movements of animals to track them autonomously in real time,to enable the drone to respond to certain types of animal behaviour (mating, hunting),
or to perform in-flight classification of animal species from real-time video.

11.4

Differential GPS PPK/RTK

Ground based surveying has made widespread use of high accuracy GPS, particularly
real-time kinematic (RTK) correction systems which enhance the precision of positional
information derived from satellite data, yielding, typically centimetre precision in three
dimensions. With drone workflows the traditional approach to achieve such levels of
precision with survey data is to calibrate models using RTK-GPS surveyed ground control
points during post-processing (Cunliffe et al., 2016, Duffy et al., 2018). This can be atime-consuming activity and therefore reducing/removing the need for ground control isdesirable if high geospatial accuracy workflows are desired from drones. This is particularly true when environments are inaccessible or budgets are tight, since the RTK method
requires users to have access to expensive GNSS equipment (costing up to €20K). There
are now methods for achieving high accuracy ground-based data for a fraction of theabove stated cost, exploiting open-source lightweight GNSS receivers such as PiKSI19(Varela et al., 2019) however, a preferable method would be to do so in-flight using an
on-board RTK-type system. Until recently the issue was the speed with which the GPS
sensor on the drone could communicate with the base station to deliver a positional
solution in three dimensions. There are now systems available on the market that are
beginning to offer workable solutions to this challenge. One example is the Ebee RTK
system: a fixed wing drone equipped with RTK-GPS which claims to deliver sub-decimeter accuracy data without the need for ground-control. It does of course, still require abase station to achieve in-flight accuracies to the stated level. Forlani et al. (2018) used
this system and showed that, with the inclusion of just one additionally-surveyed groundcontrol point to the workflow, the vertical error (which is usually larger than the x,y error)
could be constrained to within 3 cm. The continued issue is that drones equipped with
RTK technology remain much more expensive than standard consumer drone systems(perhaps as much as 30 times more expensive per unit), so there is no real cost saving in
hardware terms with these systems over a traditional workflow (where a drone + RTKGPS on the ground are used in combination). However, there would be considerable dataprocessing time savings.

19

https://www.swiftnav.com/piksi-multiDRONES FOR CONSERVATION102

As an alternative to RTK, post-processing kinematic (PPK) GPS solutions are also available
on some drones. They differ from RTK systems by not explicitly requiring a dedicated basestation in some regions of the world (e.g. the USA where there is a good network of public
base stations that can be used to post-process the data ex situ). RTK corrects data in flight,
whilst PPK data are corrected after the flight. These are emerging systems and it is not clear
where the best benefits for the conservation community lie. However, within a few years we
expect that the availability of such systems for drones will be more widespread since highpositional accuracy is required for accurate navigation, surveying and safety.

11.5

SwarmsSwarms are multiple drones in simultaneous operation. Operationally, swarm appli­
cations tend to be limited to performance or military applications – for example therecord breaking performance of 1374 drones over the City Wall of Xi’an (Figure 35) or
the 2019 Super Bowl. Even within the military, swarms are a relatively new capability,
and so it will likely be some time before civilian technology develops to the same level offunction. Despite the fact that legislation in many areas of the world precludes the general use of drone swarms, there are potential various benefits within ecology andconservation that can be imagined should swarm operations become possible, and thelaw be relaxed in future. From a mapping perspective, swarms can be deployed to map
larger areas more efficiently than is possible with a single aircraft. For example, from asingle launch point, several co-operating drones could fly outwards to collect aerial photography data; allowing improved spatial coverage as compared to a single drone within
the same time-window. If such a system could be created, it would also have potentiallyvaluable use for anti-poaching scenarios where rapid response data are needed overpotentially large areas. Another imagined application would be collecting data remotelyfrom dynamically moving targets (e.g. tagged wild animals), where cooperating aircraft
could hunt for roaming creatures. To realise this, hardware capabilities would need toinclude within-swarm communication (drone-to-drone, and drone-to-base) and tools to
optimise coverage and avoid collision.

Figure 35: Drone swam over the city wall of Xi’an. source: Youtube

DRONES FOR CONSERVATIONDRONES, SOUND, AND ANIMALS

Dr. Laura Kloepper, Notre Dame, USA

Laura Kloepper is an Assistant Professor in the Department of Biology at Saint Mary’s
College in Notre Dame, Indiana. Her research focuses on understanding the sensory
and behavioral processes underlying echolocation in toothed whales and microchiropteran bats, two suborders of mammals that convergently evolved echolocation.
Laura uses drones to record the acoustic and flight behaviour of groups of bats. By
equipping the drone with microphones and thermal imaging cameras, the drone canbe manoeuvred in 3D space to understand how bats use their echolocation and modify their flight to avoid collisions while flying at very high speeds. An off-the-shelf drone was modified for the research, which was a solution
to record high-quality sound without compromising flight performance of the drone.

Key pieces of advice for conservation drone practitioners:
1.

It is important to understand that noise disturbance from drones can have a large effect on animals,
and that the noise profiles of drones vary wildly by manufacturer. Many animal species hear very
differently than humans, so it’s crucial to characterize the noise profile of your drone of interest while
also considering the hearing range of your target species. Even if you’re just photographing animals witha drone, noise disturbance can have negative effects on the behaviour of animals including feeding, social,
and reproductive behaviour.

2.

When studying a species that has yet to be recorded with a drone (such as we did with bats), it’s crucial
to develop a conservative plan to both assess the species response to the drone and minimize behaviouraleffects of the drone on the animal.

Further information:
1.

Fu, Y, Kinniry, M, Kloepper, LN. The Chirocopter: A UAV for recording sound and video of bats at altitude.
Methods Ecol Evol. 2018; 9: 1531–1535.

2.

Kloepper, L.N. and Kinniry, M. 2018. Recording animal vocalizations from a UAV: bat echolocation during
roost re-entry. Scientific Reports.

Ground-based image (from thermal video) of bats flying with a drone hovering at 10m altitude
demon­strates that the bats are not disturbed by the drone. © Laura Kloepper

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11.6

Autonomy in power and charging

One of the most restrictive harwdare features in modern consumer drone technology isbattery life (see section 5.3), where LiPo battery life tends to fall within the 15 minute to 45 minute boundary for most multi-rotor aircraft (fixed wings may have longer
endurance given their enhanced aerodynamics). In the last years, the industry has madestrong steps towards improving efficiency and battery longevity per unit weight, withmany systems now having ‘smart batteries’ that deliver a longer life-span and improved
information about state and, in some cases, improved energy delivery rates. To realiselong endurance missions there is a recognition that drones must move towards moreautonomous power systems, e.g. self-powered through solar technology or autonomous
charging capabilities. Current science and technology investigations are advancing thesethreads, for example by:•

Evaluating alternative fuel sources such as hydrogen fuel cells which have greater
endurance per unit weight than current lithium-based sources. An example is theB-shark Narwhal 2 multi-rotor system which claims to deliver 2 hours flight timefrom a single battery. Hydrogen cells are also likely to be less damaging environmentally than lithium batteries which are currently difficult to dispose of sustainably.

•

Autonomous charging capabilities are being investigated whereby drones could
potentially re-charge themselves when battery levels drop too low. This is alreadybeing achieved through landing pads (skysense.co) which charge the battery oncethe drone has landed, requiring minimal pilot intervention. Simic et al. (2015)
proposes a method for resonance-based wireless energy transfer which would
allow a drone battery to charge when proximal to a power pylon.

•

Equipping drones with solar charging capabilities directly offers another method
for improving autonomy. Examples of this so far have been trialled in large concept wing-based models, such as NASA’s Helios drone (Figure 36) and the newconcept Ordnance Survey drone. These systems are, by necessity, much larger
than standard off-the-shelf multi-rotors and they are expensive to build and operate. The addition of solar panels increases weight resulting in there being a finebalance between size and energy requirements.

Figure 36: Example of solar-powered wing drone. © NASA

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11.7

Upscaling, data assimilation, remote sensing workflow

Whilst there is a plethora of studies using drones in isolation, there remain untapped
opportunities to synthesise drone data into wider remote sensing workflows. Typically,drone studies present themselves as improvements upon other remote sensing datasetsby virtue of the finer grained data, but as we have discussed, operational issues prevent
drones from delivering regional or global extent coverage. Data fusion approaches are
already emerging in the precision agriculture and environmental science sectors – using
fine-scale drone data to improve the quality of land cover mapping retrievals from satellite data. In these cases, the fine-scale information from the drone is highly useful for
resolving spatial patterns in land cover which are particularly useful in complex environments. There remain as yet untapped opportunities for assimilation of drone data into
broader RS workflows. We propose that drone data using a variety of sensors(Chapter 6) can deliver:•

Information for calibration or validation of satellite data. Vicarious calibration
campaigns tend to rely on point-based observations of land or sea surface spectral
properties, and drones could improve the spatial representation of such data byallowing sensors to be moved quickly across small portions of the scene. Puliti etal. (2018) have shown the validity of drone data for validating forest stock estimates obtained from sentinel-2 data, for example.

•

In data assimilation schemes, fine-grained observations from drones could provevaluable for improving model outputs. To provide one example, Hill et al. (2011)
explain that “the use of coarse-scale observations in ecological data assimilation
schemes is complicated by spatial heterogeneity and nonlinear processes” andby combining frequent coarse-resolution observations (e.g. from satellites) withtemporally sparse fine-resolution measurements (e.g. we suggest from drones),
the data assimilation scheme has the potential to provide less biased results. So
far, this approach has not been tested with drone data, but we suggest it could bea useful way forward.

•

Models of radiative transfer which are used frequently within RS science to predict surface radiative properties from top-of-atmosphere measured signals (e.g.
from satellite data) are usually driven in forward mode using synthesised estimations of spatial landscape structure. Inclusion of real data from drone-based
SfM for example, into these RT schemes could potentially improve the quality of
inversion results, delivering higher quality data to users.

•

Fluid lensing approaches are high-tech methods for deriving cm-resolution
multispectral 3D maps of submerged aquatic systems, which allow the adverse
refractive distortions from ocean waves to be removed (Chirayath and Earle, 2016,
Chirayath and Instrella, 2019). Fluid lensing relies on robust physics and requires
specialised equipment, but shows great promise for ‘seeing through waves’ to mapbenthic substrates.

The above innovations have not yet been realised operationally, and there will need to besignificant scientific and technical investment to deliver meaningful products that can beused by those in the ecology/conservation field. We propose that these represent usefulfoci for future remote sensing work, downstream of which will be benefits for all who use
data and products from satellite systems.

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11.8	Legislative framework – better integration of drones into
airspace
Airspace is a complex, invisible, three-dimensional infrastructure. Until civilians hadaccess to low-cost drones, access to airspace was the privilege of those with a pilots’
license and access to expensive aircraft. Drones disrupt access to airspace to some extent,
although we argue that there is an airspace stratification that applies to lightweight drone
operators and pilots of other aircraft, by virtue of the technological and safety limits
applying to the operations of small drones.
Rules of airspace access are controlled by aviation authorities, and there are clear,internationally-accepted, rules that pervade airspace management and access globally– Figure 37 depicts these generalised rules. Broadly speaking lightweight drones, if
operated according to widely accepted protocols (see Chapter 7; e.g. <100 m above
ground height and line-of-sight-operations) can be used without issue in Class G airspace(Figure 37), which allows pilots to operate according to ‘visual flight rules’ (VFR). VFR
are where the drone is kept within the pilot’s sight, and action is taken to watch for otherair users and maintain a safe distance from them.
We argue that in the majority of cases in ecology/conservation settings operations
will take place in Class G airspace, and so operations operations should not be unduly
restricted in many areas. Most of the other airspace classes listed in Figure 37 relate
to airspace above the 100 m height limit and are typically found in close proximity to
airports or landing strips used by other air traffic (e.g. parachuters or gliders). Of course,
national and local rules may restrict drone deployments – such as within national parksand over private property, so drone pilots should check before flying.

Figure 39: Urban Density (2014). © Mark Lehmkuhler

107

DRONES FOR CONSERVATIONIn the future, it is likely that airspace management systems will have to change to accom­mo­date drones of all sizes. New models are being drawn up that would allow for integration of drones into current airspace management systems. For example, Figure 38
shows a conceptual model being developed by a Californian start-up (AirMap) that will
use a software system to keep drones in their own airspace by allowing them to communicate with other aircraft. The future legislation and management of airspace willundoubtedly be decided by federal/national authorities. To provide an example, a new
five-year US-based Federal Aviation Authority “Reauthorization Act of 2018” was signed
into law on 5th October 2018. This law confirmed some of the controversial rules that the
FAA considers critical to its ability to regulate drone traffic. Moreover, it paved the way
for funding for drone-specific air-traffic control systems capable of tracking both traditional aircraft and commercial drones.

Figure 38: Airspace management system that incorporates lightweight drones.
© www.flyingmag.com/atc-for-drones

108

the current Part 101 and 107 regulations, NASA, in collaboration with FAA, is developing the
DRONES FOR CONSERVATION
prototype Flight Information Management System (FIMS). FIMS supports informationexchanges andprotocols for Operators to cooperatively share information and to access needed FAA-provided
information for common situational awareness among all UTM stakeholders (Operators, othergovernment agencies, and the FAA) and will be a core component of the overall UTM ecosystem.

The proposed goal of this legislation was to “provide safe, low-altitude operations forboth drones and manned (sic) aircraft. The longer-term goal is to accommodate what is
1.3 expected
ConOps to
Scope
be enormous growth in the use of commercial drones, in an efficient way”.
It uses focusesa NASA-designed
system for tracking
dronesthegroundunmanned
This ConOps
on UTM operations
below 400
feetcalledabove
levelaircraft(AGL).sysMost of thetems traffic
management
system(Figure39).airspace
The planunderis that400
theft,
UTM
will beinformation
presented
will apply(UTM)
to UTM
operationsin anybut operationalanda centralpoint of may
contact
fordueall drone
users
including hobbyists,
air traffic control,law
technical
requirements
vary
to uniquecharacteristics
and implicationsof the airspaceclass
in which
UAS are operating.
In elsethis interested
Version 1.0,
the usetraffic.
casesSimilarly,
presented
specific to Class
enforcement
and anyone
in dronetoare
the mostly
generalised
G operations.
G airspaceis the 37),
portionof airspace
theaerial
NAS thathasintonotdiscrete
been designated as
airspaceClass
classification(Figurethe UTMdividesinthe
volumecontrolled
airspace(i.e.,definedClass A,
B, C, D, toor theirE). Itheightis therefore
designateduncontrolled
airspace
airspaceclasses,accordingand proximity
to otherhazards andair (seeFigure traffic.
2). ATCThe
hasUTMno responsibility
toprovideseparation
servicesinClassG
airspace,rather,will identify aircraft in each zone, and “communicate with, or influencemanned
aircraftthem
cooperatively
theiroperations
on specified
principles
operations.
to move inmanage
a direction
thatis safe forbased
all aircraft”.
As a concept,
thisofoffersa rela- In orderto provide
UAS
with
the
same
accessasmannedaircraft,
UTM
isdesignedtoprovidea similar means
tively simple way to manage the flow of drones into airspace, but in practice the complexof cooperative
traffic
management
for
UAS
and
other
participating
aircraftin
thisairspace.
ities of doing so, particularly with respect to prioritising particular airspace users andcommunicating with drone pilots, would require significant advances in drone-to-drone
The FAAdevelop subsequent
ConOpsversions that coincidewith concept
development ofandwilldrone-to-otherairspace and
UTM communications.
These systems
are not operaincreasingly
morecomplex
UTM
operations
andenvironments
acrossallairspaceclasses (seetional yet, but give a flavour of how future airspace access may be governed. This could
Appendix B for airspace class descriptions). The scope will be expanded to cover a range of operations
either benefit or hamper ecology/conservation drone operations depending on the levelin controlled airspace, as well as those that transit to and from a UTM environment and the ATMof mandate afforded to lightweight drones over other aerial operations.

environment.

Figure 39: Unmanned
exploredby the FAA. © NASA
FigureTraffic
2. UTMManagement
Operations inSystem
Contextbeingof Airspace
Classes(https://semiengineering.com/faa-traffic-management-anticipates-flying-cars/)

3|PageDRONES FOR CONSERVATIONLOCAL-SCALE IMPACTS OF BOAT ANCHORAGE ON SEAGRASS MEADOWS

Dimitris Poursanidis, Foundation for Research and Technology – Hellas, the Remote Sensing lab

Dimitris is an Earth Observation Data Analyst, and Marine ecologist, who loves tocombine new technologies with field data, trying to provide useful information forconservation activities.
Fine scale assessment of the ecological (health) status of the seagrass meadows, in the
National Marine Park of Alonissos and Northern Sporades in Greece, is conducted bymeans of SCUBA diving and applying non-destructive methods, such as drone surveys. During the surveys, which produce data at the scale of centimeters, information
related to shoot density, the compactness of the meadows, the impacts of human activities and the occurrence oflitter/debris, is evaluated. The use of drone allows the collection of data at the scale of the bay, or cove, and thepost processing of the collected information can provide useful insights on the number of scars at each cove, thespatial location and the size. As such, targeted measures and activities can be implemented in order to minimize
the impacts. This information supplements the satellite remote sensing data, which can be used for the locationof areas with high densities of boats during the summer period.

Key advice for conservation practitioners:
1.
2.

Understand the limitations of the drone in the area you will work and tailor the flight time based on theposition of the sun (e.g. avoiding sun glint).
Avoid midday flights in order to minimize moving obstacles on the sea surface (boats, swimmers, etc).

Ultra-high resolution (3cm pixel size) view of seagrass meadows (Posidonia oceanica) impacted by thecontinued anchroage of leisure boats. The scars left by the anchorage create openings in the meadows,
visible from drone but not satellite.

109

Seaweed farming in Ankilimionga in the Mahafaly land- and seascape in the Southwest of Madagascar.
© Martina Lippuner/WWF-Africa

12

111

DRONES FOR CONSERVATIONSUMMARY OF CASE STUDIES
Monitoring plant biomass with drone photogrammetry(Dr. Andrew Cunliffe, University of Exeter)

29

Using drones to collect whale lung samples(Dr. Vanessa Pirotta, Macquarie University)	

33

Empowering traditional communities and front-line staff to use drones forconservation (Felipe Spina Avino, WWF-Brazil)

61

UAS4Ecology: Drones for ecological research(Urs A. Treier & Dr. Signe Normand, Aarhus University)

67

Mapping habitats of the Great Barrier Reef
(Dr. Karen Joyce, James Cook University)

85

Surveying river dolphins in the Amazon(Marcelo Oliveira, WWF-Brazil)

89

Assessing mangroves in the Rufiji Delta, Tanzania(Aurélie Shapiro, WWF-Germany)

93

Bear Cubs: your lunch is in the air(Leonardo Bereczky and Alexandra Dumitrescu, WWF-Romania)

97

Drones, sound, and animals(Dr. Laura Kloepper, Notre Dame)

103

Local-scale impacts of boat anchorage on seagrass meadows(Dimitris Poursanidis, Foundation for Research and Technology, Hellas, Greece)

109

“Great Immigration Birds Eye View” by Thomas Vijayan. Highly commended, Drone Awards 2018,
Wildlife Category. © Thomas Vijayan /Drone Awards/Art Photo Travel

13

113

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Kandahalagala Island in the Huvadhu Atoll, The Maldives. Photo captured with a Ricoh GRII
mounted on a 3DR Solo © James Duffy