DOI: 10.5061/dryad.cc2fqz6gg
title: Data and R-code from: Migration, habitat and hunting style do not affect the malar stripe of different falcon species

description: The solar glare hypothesis suggests that malar stripe of a falcon
 decreases the sun’s glare in the eye, possibly increasing their hunting
 success. The amount of sunlight an individual experiences could be
 affected by its migratory strategy, hunting strategy, or main habitat.
 However, it is not known if these environmental variables impact the size
 and intensity of the malar stripe. Therefore, this study aimed to analyse
 differences in size and intensity of malar stripes between individuals of
 twelve falcon species with different migratory strategies, habitats, and
 hunting styles distributed worldwide. The malar stripes of twelve falcon
 species were measured and scored using more than 6000 photos from citizen
 science repositories. The measurements of the malar stripes were first
 reduced with a principal component analysis (PCA) and then analysed using
 a linear mixed model that included migratory strategy, habitat, and
 hunting style as fixed factors and several posture variables as random
 factors. The relationships between the measurements of the malar stripe
 and solar radiation of the individual’s location were also analysed using
 linear mixed models. Overall, we found no differences in malar stripe size
 and intensity between species with differing migratory strategies, habitat
 and hunting styles. The relationships between various characteristics of
 the malar stripe and solar radiation did depend on the species and the
 habitat the individual occupied. Therefore, migratory strategy, habitat,
 and hunting style do not markedly influence the size and intensity of
 malar stripes across falcon species, suggesting that other mechanisms,
 such as thermoregulation or camouflage, also play a role.
description: For this study, we compared the malar stripes of 12 falcon
 species with differing migratory strategies  (migratory, partially
 migratory, and sedentary), habitats (grassland, woodland, shrubland and
 forest), and hunting styles (aerial, insessorial and generalist). We used
 two online citizen science repositories, iNaturalist (iNaturalist, n.d.)
 and the Macaulay Library (Macaulay Library, n.d.), to get access to photos
 of the 12 different falcon species. <em>Table
 </em><em>1</em><em>. The 12 falcon species
 included in this study with their migratory strategy, habitat, and hunting
 style</em><em>.</em> 
 <strong>Scientific
 name</strong> 
 <strong>English name</strong> 
 <strong>Migratory
 strategy</strong> 
 <strong>Habitat*</strong> 
 <strong>Hunting style</strong>
 <em>Falco
 amurensis</em> Amur
 Falcon Migratory
 Grassland 
 Insessorial 
 <em>Falco columbarius</em>
 Merlin 
 Migratory 
 Woodland 
 Aerial 
 <em>Falco naumanni</em> 
 Lesser Kestrel 
 Migratory 
 Grassland 
 Generalist 
 <em>Falco subbuteo</em>
 Eurasian Hobby 
 Migratory 
 Woodland 
 Aerial 
 <em>Falco cenchroides</em> 
 Australian Kestrel 
 Partially Migratory 
 Woodland 
 Generalist 
 <em>Falco biarmicus</em>
 Lanner Falcon 
 Partially Migratory 
 Shrubland 
 Aerial 
 <em>Falco sparverius</em> 
 American Kestrel 
 Partially Migratory 
 Grassland 
 Insessorial 
 <em>Falco tinnunculus</em>
 Eurasian Kestrel 
 Partially Migratory 
 Shrubland 
 Aerial 
 <em>Falco berigora</em> 
 Brown Falcon 
 Sedentary 
 Woodland 
 Aerial 
 <em>Falco chicquera</em> 
 Red-necked Falcon 
 Sedentary 
 Woodland 
 Aerial 
 <em>Falco novaeseelandiae</em> 
 New Zealand Falcon 
 Sedentary 
 Forest Aerial
 <em>Falco
 rufigularis </em> Bat
 Falcon Sedentary
 Forest 
 Aerial 
 For each species, we analysed 500 photos that were
 equally distributed over its distribution range. Per individual, we
 measured and calculated six measurements of the malar stripe: the width of
 the malar stripe, which is the thickness of the stripe; the contiguity
 with the hood, which is the connection of the malar stripe to the dark
 plumage on the hood; the prominence, which is the intensity of the malar
 stripe; the length of the malar stripe which is the maximum distance from
 the dorsal to the ventral end of the stripe; the elongation, which is
 calculated by dividing the length by the width; and the surface, which is
 calculated by multiplying the width by the length. The
 width and length were measured using an on-screen measuring tool (Aequo),
 and these two measures were used to calculate the elongation and surface
 of the malar stripe. The contiguity and prominence were scored using a
 scoring template. We also scored the width and length of the malar stripe
 and used these scores to calculate a scored elongation and surface.
 Because the position of the birds varied a lot throughout the photos, the
 measurements were done relative to the width and height of the bird’s eye.
 We performed each measurement three times and used the average of these
 measurements in the analysis. Also, the bird's posture was scored
 using a scoring template. Finally, we obtained the
 average direct normal irradiation (kWh/m<sup>2</sup>) using a
 Global Solar Atlas for each region a photo was taken in. The Handbook of
 Energy, "Section 10 - Solar"  (2013) stated that “Direct Normal
 Irradiation (DNI) is the amount of solar radiation received per unit area
 by a surface that is always held perpendicular (or normal) to the rays
 that come in a straight line from the direction of the sun at its current
 position in the sky.”  Hence, we used direct normal irradiation as a proxy
 for the amount of sunlight an individual experiences throughout the
 year.
description: # Data and R-code from: Migration, habitat and hunting style do not affect
 the malar stripe of different falcon species
 [https://doi.org/10.5061/dryad.cc2fqz6gg](https://doi.org/10.5061/dryad.cc2fqz6gg) ## Description of the data and file structure ### Files and variables #### File: dat\_total.csv **Description:** Measurements and scores for different aspects of the malar stripe for 12 falcon species. ##### Variables * ID: unique identifier for each photo * Library: online citizen science repositories * Eye_width_1: First measurement of eye width on the picture (in centimeters, cm hereafter) * Eye_width_2: Second measurement of eye width on the picture (cm) * Eye_width_3: Third measurement of eye width on the picture (cm) * Eye_heigth_1: First measurement of eye height on the picture (cm) * Eye_heigth_2: Second measurement of eye height on the picture (cm) * Eye_heigth_3: Third measurement of eye height on the picture (cm) * Width_template: Score of malar stripe width based on the scoring template * Width_measure_1: First measurement of malar stripe width on the picture (cm) * Width_measure_2: Second measurement of malar stripe width on the picture (cm) * Width_measure_3: Third measurement of malar stripe width on the picture (cm) * Contiguity: Score of malar stripe contiguity based on the scoring template * Prominence: Score of malar stripe prominence based on the scoring template * Length_template: Score of malar stripe length based on the scoring template * Length_measure_1: First measurement of malar stripe length on the picture (cm) * Length_measure_2: Second measurement of malar stripe length on the picture (cm) * Length_measure_3: Third measurement of malar stripe length on the picture (cm) * Head_vertical: Vertical position of the head based on the scoring template * Head_horizontal: Horizontal position of the head based on the scoring template * Head_rotation: Rotation of the head based on the scoring template * Compression: Compression of the head based on the scoring template * nr_individuals_on_photo: Number of individuals on the picture * Data_analyse: Date and time when the picture was analyzed * Common_name: Common name of the falcon species * Scientific_name: Scientific name of the falcon species * Date: Date at which the picture was taken * Country: Country in which the picture was taken * Latitude: Coordinates at which the picture was taken * Longitude: Coordinates at which the picture was taken * State: State or region in which the picture was taken * Solar: Average direct normal irradiation (kWh/m2) based on the Global Solar Atlas * Eye_width_average: Average of eye width based on three measurements (cm) * Eye_heigth_average: Average of eye height based on three measurements (cm) * Width_average: Average of malar stripe width based on three measurements (cm) * Length_average: Average of malar stripe length based on three measurements (cm) * Width_Relative_to_eye: Width of malar stripe relative to the eye width * Length_Relative_to_eye: Length of malar stripe relative to the eye length * Elongation_template: Elongation of the malar stripe based on the scoring template * Elongation_Relative_to_eye: Elongation of the malar stripe relative to the eye length * Species: Common name of falcon species * Migratory_strategy: Categorical variable with levels migratory, partially migratory and sedentary * Habitat: Categorical variable with levels grassland, shrubland, woodland, and forest * Surface: Surface of the malar stripe based on the scoring template * Surface_Measured: Surface of the malar stripe based on measurements of width and length (cm²) * Hunting_style: Categorical variable with levels aerial, generalist and insessorial ## Code/software R-script to analyze the analyze the differences in size and intensity of malar stripes between individuals of twelve falcon species with different migratory strategies, habitats, and hunting styles distributed worldwide. We used the latest versions of package tidyverse, lme4, car and lsmeans. **Input** = the csv-file that belongs to this Dryad-entry **Workflow** 1. Create subsets of the data for each of the sedentary subspecies (will be analyzed later on) 2. Determine data distribution of each variable of the malar stripe 1. For all 12 species together 2. For the four sedentary species (bat falcon, brown falcon, New Zealand falcon, Red-necked falcon) 3. For each sedentary species separately 3. Run linear mixed models for each variable of the malar stripe with migratory strategy, habitat and hunting style as fixed factors 1. For all 12 species together 2. For the four sedentary species (bat falcon, brown falcon, New Zealand falcon, Red-necked falcon) 3. For each sedentary species separately 4. Run linear mixed models for each variable of the malar stripe with solar radiation as fixed factor (only for sedentary species) 1. For the four sedentary species (bat falcon, brown falcon, New Zealand falcon, Red-necked falcon) 2. For each sedentary species separately ## Access information Other publicly accessible locations of the data: * AVONET-database: [https://onlinelibrary.wiley.com/doi/full/10.1111/ele.13898](https://onlinelibrary.wiley.com/doi/full/10.1111/ele.13898) Data was derived from the following sources: * iNaturalist ([https://www.inaturalist.org/, ](https://www.inaturalist.org/observations?place_id=any&quality_grade=research&verifiable=any)open source data) * Macaulay Library ([https://search.macaulaylibrary.org/, ](https://search.macaulaylibrary.org/catalog?age=adult)open source data)