United States Department of Agriculture

Forest Rocky Mountain General Technical Report July 2017

Service Research Station RMRS-GTR-368

Developing a Monitoring Program for Bird 

Populations in the Chiricahua Mountains, 

Arizona, Using Citizen Observers: Initial Stages

Joseph L. Ganey, Jose M. Iniguez, 

Jamie S. Sanderlin, and William M. Block 
Ganey, Joseph L; Iniguez, Jose M.; Sanderlin, Jamie S.; Block, William M. 2017. 

Developing a monitoring program for bird populations in the Chiricahua 

Mountains, Arizona, using citizen observers: Initial stages. Gen. Tech. Rep. 

RMRS-GTR-368. Fort Collins, CO: U.S, Department of Agriculture, Forest Service, 

Rocky Mountain Research Station. 30 p.

Abstract

The Madrean Sky Island region is an ecologically important area harboring exceptional biodiversity, including a unique avifauna that supports a thriving ecotourism 

industry in southeastern Arizona. This area has been impacted by several large wildfires 

in recent decades. These wildfires have altered vegetation composition and structure 

in forests and woodlands, and the effects of these changes on bird populations and 

distribution are not well understood. We studied occupancy and habitat associations 

of forest and woodland birds within five mountain ranges in southeastern Arizona from 

1991 to 1995, before these fires occurred. The resulting data provide a unique opportunity to compare postfire bird populations with populations in these ranges during the 

1990s, but funding to accomplish the necessary postfire bird sampling has been limited. 

Consequently, we are exploring the feasibility of using skilled citizen observers to monitor bird occupancy and distribution. This report documents the early stages of an effort 

to sample bird populations in the Chiricahua Mountains, Arizona using citizen observers. It describes field methods, presents preliminary results, summarizes early lessons 

learned, and outlines future steps necessary to design and implement a rigorous monitoring program using citizen observers to sample bird populations in the Madrean Sky 

Islands. 

Keywords: avifauna, biodiversity, bird populations, citizen science, climate change, 

Madrean, monitoring, wildfire

Cover photo: Cave Creek area, Chiricahua Mountains, Arizona (center). Also shown 

are selected iconic bird species found in the area, including broad-billed hummingbird, 

Montezuma quail, buff-breasted flycatcher, Mexican jay, elegant trogon, yellow-eyed junco, 

Arizona woodpecker and summer tanager (left top to bottom followed by right top to bottom; 

scientific names for bird species are shown in table 3). Center photo by Jamie S. Sanderlin 

(U.S. Forest Service), all others by Will Jaremko-Wright (used by permission).
Authors

Joseph L. Ganey is a Research Wildlife Biologist in the Wildlife and Terrestrial 

Ecosystems Research Program, Rocky Mountain Research Station, Flagstaff, Arizona 

jganey@fs.fed.us.

Jose M. Iniguez is a Research Ecologist in the Wildlife and Terrestrial Ecosystems 

Research Program, Rocky Mountain Research Station, Flagstaff, Arizona jiniguez@

fs.fed.us.

Jamie S. Sanderlin is a Quantitative Vertebrate Ecologist in the Wildlife and Terrestrial 

Ecosystems Research Program, Rocky Mountain Research Station, Flagstaff, Arizona 

jlsanderlin@fs.fed.us.

William M. Block is a Research Program Manager for the Wildlife and Terrestrial 

Ecosystems Research Program, Rocky Mountain Research Station, Flagstaff, Arizona 

wblock@fs.fed.us.

Acknowledgments

The Desert Landscape Conservation Cooperative (U. S. Bureau of Reclamation 

and U.S. Fish and Wildlife Service), and internal climate change funds from USDA 

Forest Service Rocky Mountain Research Station (RMRS) provided funding for this 

project. We are especially grateful to our partners and citizen scientist volunteers from 

Friends of Cave Creek Canyon: P. Abbott, L. and T. Arny, A. Bammann, B. Barker, 

B. and S. Birky, W. Brown, M. Jackson, P. LaRue, J. Lewis, G. Montgomery, T. Morgan, 

R. Peters, J. Pratt, B. Rodrigues, G. and R.A. Rowlett, R. Van Buskirk, K. Walz, 

R. Webster, C. West, and J. Yerger. We also thank the RMRS field crews for their 

hard work sampling birds and vegetation: L. Hall, C. Howell, L. Seguela, B. Maynard, 

M. Morrison, A. Rifa, P. Scott, R. Hoyer, R. Lange, J. Whittier, and R. Wilson (1990s), 

and G. Furr, D. Gusset, W.S. Hampton, and W. Jaremko-Wright (2014). We thank 

K. Aerni, A. Olenberg-Meltzer, and W. Jaremko-Wright for additional vegetation sampling in 2015, R. Lopez, B. Strohmeyer, and S. Vojta for their assistance with relocating 

point count stations, and S. Vojta, G. Furr, A. Toscas, W. Jaremko-Wright, K. Aerni, 

and A. Olenberg-Meltzer for assistance with data entry. We thank the U.S. Forest 

Service Douglas, Nogales, Safford, Santa Catalina, and Sierra Vista Ranger Districts 

(Coronado National Forest) and Fort Huachuca for logistical support, especially R. 

Biggs, A. Casey, J. Copeland, K. Ellet, R. Gay, S. Guy, S. Helin, J. Higgins, J. Kraft, 

J. Roberts, M. Ruggiero, D. Sebesta, S. Stone, J. Taiz, and K. Warner. The U.S. Forest 

Service Tucson Dispatch office was invaluable in keeping our crews safe. The Santa 

Catalina Ranger District (R. Biggs, R. Right), the Santa Rita Experimental Station/

Florida Work Station (M. Heitlinger), and the Audubon Research Ranch were helpful 

in providing temporary housing for field crews. A. Lynch (RMRS) helped us coordinate 

activities with Coronado National Forest personnel. We also thank the Southwest Fire 

Science Consortium, U.S. Fish and Wildlife Service (S. Spangle), Nongame Birds 

Program of the Arizona Game and Fish Department (E. Juarez), Sonoran Joint Venture 

(C. Beardmore, R. Maesta), Tucson Audubon Society, Chiricahua National Monument, 

Sky Island Alliance, and The Nature Conservancy for their support. W. Jaremko-Wright 

graciously allowed us to use several of his excellent photographs. This report was 

improved by comments from C. Campbell and A. D. Flesch.
All Rocky Mountain Research Station publications are published by U.S. Forest Service 

employees and are in the public domain and available at no cost. Even though U.S. Forest 

Service publications are not copyrighted, they are formatted according to U.S. Department 

of Agriculture standards and research findings and formatting cannot be altered in reprints. 

Altering content or formatting, including the cover and title page, is strictly prohibited.

Contents

Introduction................................................. 1

Case Study: Implementing Citizen Science....................... 4

Study Area.............................................. 4

Methods................................................ 6

Results and Discussion................................... 15

Future Directions ........................................... 22

Conclusions ............................................... 24

References ................................................ 24
USDA Forest Service RMRS-GTR-368. 2017. 1

Introduction

The Madrean Sky Islands region, located in the southwestern United States and 

northern Mexico (fig. 1), is an ecologically important area characterized by numerous 

mountain “islands” (the Madrean archipelago) surrounded by desert and semi-desert 

“seas” (Flesch 2014; Gelbach 1981; Warshall 1995). This inland archipelago provides 

a stepping stone between two large mountain chains, connecting the Rocky Mountains 

and its associated plateaus with the Sierra Madre Occidental (Flesch 2014; Flesch et 

al. 2016; Gelbach 1981; Warshall 1995), and forming a north-south mountain axis that 

crosses several climatic zones.

Among the world’s sky island complexes, the Madrean Sky Islands are unique 

in several ways. This region harbors a larger number of sky island mountain ranges 

than other complexes (variously estimated at 40 ranges by Warshall [1995] and 55 

ranges by Deyo et al. [2013]). In addition, it is the only archipelago having the distinct 

north-south connection to two major mountain chains, extending from subtropical to 

temperate latitudes (Flesch 2014; Warshall 1995) and straddling two major floristic 

(Neotropic/Holarctic) and faunal (Neotropic/Nearctic) realms (Halffter 1987; Escalante 

et al. 2004). The result is exceptional biodiversity, including plants and animals with 

Madrean, Petran (Rocky Mountain), Sonoran, Chihuahuan, and Sinaloan (e.g., lowland Neotropical) affinities (Ferguson et al. 2013; Flesch 2014; McLaughlin 1995; 

Figure 1—General location and extent of the Madrean Sky Island region within 

the continent of North America. Source: Miguel Villareal, U.S. Geological Survey, 

Western Geographic Science Center; (http://geography.wr.usgs.gov/science/

EcoMod/; downloaded 1 July 2016). 
2 USDA Forest Service RMRS-GTR-368. 2017.

Van Devender et al. 2013; Warshall 1995). Moreover, the vertical relief associated with 

these mountains allows these species to form a wide variety of ecological communities 

stratified along elevational gradients (Niering and Lowe 1984; Shreve 1915; Whittaker 

and Niering 1964). Because of this biodiversity, the Madrean archipelago is recognized 

as a global resource of high conservation value (Foreman 2000; Spector 2002; Supplee 

and McFarland 2013; Van Devender et al. 2013).

The avifuana of the Madrean Sky Islands region is of particular conservation interest 

in the United States (e.g., Balda 1967; Marshall 1957; Supplee and McFarland 2013). 

Several species with Madrean affinities reach their northern range limits in this region, 

including iconic species such as the elegant trogon (Trogon elegans). These species are 

much sought after by bird watchers, resulting in a thriving ecotourism industry catering 

to bird watchers in southeastern Arizona (King and Czech 1995; Leones et al. 1998).

In recent decades, the Madrean archipelago has undergone pronounced changes due 

to climate change, wildfire, insect outbreaks, border development, and other disturbances (Barton 2005; Kupfer et al. 2005; Lynch and O’Connor 2013; O’Connor et al. 

2014; Quinn and Wu 2005), and those changes may threaten some of the unique plants 

and animals inhabiting this region (Coe et al. 2012; Falk 2013; Flesch et al. 2016; 

Ganey et al. 1996; Koprowski et al. 2005, 2013). Understanding the impacts of these 

disturbances on native plants and animals is critical to developing management strategies to conserve species and habitats (Flesch et al. 2016; Ganey et al. 1996; Misztal et 

al. 2013), yet such knowledge is largely lacking, as is information on population trends 

for most species.

We studied bird populations and habitats in forests and woodlands of five Sky Island 

ranges in southeastern Arizona from 1991 to 1995 (fig. 2). This study resulted in a rich 

data set documenting occupancy and habitat associations of forest and woodland birds 

in these ranges during that time period (Block and Severson 1992; Block et al. 1992; 

Ganey et al. 2015; Iniguez et al. 2005; Sanderlin et al. 2013). Many areas that were 

sampled for birds from 1991–1995 have subsequently burned in wildfires (table 1). 

This data set thus provides an opportunity to assess changes in occupancy and distribution of birds and the impacts of wildfires on bird communities and associated habitats. 

Due to funding constraints, however, resampling avian populations over multiple years 

within the study areas has not been feasible. Therefore, we were interested in exploring 

sampling approaches that did not require large funding commitments.

Citizen observers have been used in several research efforts and monitoring programs in recent years, and may provide a cost-effective way to collect data that would 

otherwise not be available (Barrows et al. 2016; Cox et al. 2012; Tulloch et al. 2013). 
USDA Forest Service RMRS-GTR-368. 2017. 3

Figure 2—General locations of five mountain ranges (Chiricahua, Huachuca, Pinaleño, Santa 

Catalina, and Santa Rita mountains) in southeastern Arizona where bird populations were sampled 

from 1991 to 1995. The vertical white line denotes the Arizona – New Mexico border.

Table 1—List of large (>400 ha) wildfires that burned from 1994 to 2014 

in areas where RMRS crews sampled bird populations from 1991–

1995 in four Madrean Sky Island mountain ranges. Year in which the 

fire occurred and area contained within the fire perimeter are also 

shown. Data from Monitoring Trends in Burn Severity (MTBS 2017). 

Several large wildfires also burned in the Huachuca Mountains during 

this period, but these did not overlap with the RMRS bird transects.

Mountain range Fire name Year Area burned (ha)

Chiricahua Rattlesnake 1994 10,210

Horseshoe I 2010 1,248

Horseshoe II 2011 91,501

Pinaleño Nuttall Complex 2004 12,901

Grapevine 2012 7,101

Santa Catalina Shovel 1995 497

Bullock 2002 12,860

Aspen 2003 32,361

Santa Rita Florida 2005 6,620

Greaterville 2011 778
4 USDA Forest Service RMRS-GTR-368. 2017.

Southeastern Arizona is home to many citizens who are interested in conservation 

issues and skilled at identifying birds by sight and sound. Consequently, we are exploring the feasibility of designing a program to monitor occupancy and distribution of 

birds using skilled citizen volunteers. This paper describes initial stages of this ongoing effort, and is focused on a pilot study in the Chiricahua Mountains, Arizona. We 

describe field methods used, present preliminary data resulting from this effort, summarize some early lessons learned, and describe future steps necessary to design and 

implement a scientifically rigorous citizen-science based monitoring program.

Case Study: Implementing Citizen Science

Study Area

Initial sampling during the 1990s covered the five largest sky islands in Arizona 

(fig. 2), but here we focus on a pilot study in one of those ranges. The Chiricahua 

Mountains are located in southeastern Arizona, just west of the border with New 

Mexico and just north of the border with Mexico. This range is oriented along a northsouth axis that spans approximately 56 km. Elevation ranges from approximately 

1,175 to 2,975 m. The Chiricahua Mountains are an uplifted fault block containing 

Precambrian basement rocks and Paleozoic and Cretaceous sedimentary rocks around 

a caldera complex formed by volcanic eruptions and intrusions (du Bray et al. 1999). 

A major eruption approximately 27 million years ago left a massive layer of volcanic 

ash that fused into welded rhyolite tuff (Nations and Stump 1981). Subsequent erosion 

has created steep mountain ridges and deep canyons.

Our study area consisted of oak and pinyon-juniper woodlands, pine-oak forests 

(Pinus spp. – Quercus spp.), pine forests, and mixed-conifer forests within the 

Coronado National Forest, at elevations between 1,650 m and 2,650 m. Dominant tree 

species included Arizona white (Q. arizonica), silverleaf (Q. hypoleucoides), Emory 

(Q. emoryi), Gambel (Q. gambelii), and netleaf (Q. reticulata) oaks; ponderosa (P. ponderosa), Arizona (P. ponderosa var. arizonica), Apache (P. engelmanni), Chihuahua 

(P. leiophylla), Mexican white (P. strobiformis), and border pinyon (P. discolor) pines; 

alligator-bark juniper (Juniperus deppeana); white fir (Abies concolor); Douglas-fir 

(Pseudotsuga menziesii); quaking aspen (Populus tremuloides); and Arizona cypress 

(Cupressus arizonica) (Iniguez et al. 2005).

Three large wildfires have burned in the Chiricahua Mountains since 1994, including the 1994 Rattlesnake fire, the 2010 Horseshoe fire, and the 2011 Horseshoe II fire 

(table 1). The Horseshoe II fire, which burned over 91,500 hectares, overlapped the 

entire Rattlesnake fire and parts of the Horseshoe I fire (fig. 3). An evaluation based on 

remotely sensed data (MTBS 2017) classified 58 percent, 30 percent, and 11 percent 

of the Horseshoe II fire area as having burned at low, moderate or high burn severity, 

respectively.
USDA Forest Service RMRS-GTR-368. 2017. 5

Figure 3—Perimeters of recent large wildfires (dark polygon outlined in red) within the 

Chiricahua Mountains, and locations of the original transects (squares) where bird populations were sampled from 1991 to 1995. Top: Perimeters of fires that occurred from 1991 to 

2010. Bottom: Perimeter of the Horseshoe II fire, which burned in 2011.
6 USDA Forest Service RMRS-GTR-368. 2017.

Methods

1991–1995 Study

In 1991, RMRS installed eight transects to sample bird populations in the Chiricahua 

Mountains (figs. 3 and 4). Transect starting points were randomly located and transects 

followed random compass bearings. Each transect included 12 point-count stations 

spaced at 300 m intervals along two parallel survey lines of 6 points each, except for 

one transect (E, fig. 4) of a single line with 8 stations (total n = 92 points). We counted 

birds at these points each year from 1991–1995, using the variable-radius point-count 

method (Reynolds et al. 1980). Birds were sampled at each point two to three times 

during the sampling season (April–July). Transects were surveyed by single observers, 

but we rotated observers among transects between survey occasions to reduce potential 

observer effects. Counts lasted 5 minutes at each point and were completed between 

sunrise and 4 hours after sunrise.

We sampled vegetation characteristics at each point-count station and used the 

resulting data to classify point-count stations to cover types based on species composition and basal area (details in Iniguez et al. 2005). We recognized seven cover types, 

which collectively sampled a broad elevational range (figs. 5 and 6). Arizona cypress 

Figure 4—Detail map of the central portion of the Chiricahua Mountains showing locations of 

original point-count stations (red squares) along transects (labeled A to H) established in 1991 

to sample bird populations. 
USDA Forest Service RMRS-GTR-368. 2017. 7

Figure 5—Elevation distribution by cover type for point-count stations 

(n = 91) in original transects established in 1991 to sample bird populations in the Chiricahua Mountains, Arizona. The box indicates the range 

from the 25th percentile to the 75th percentile, the solid line within the 

box indicates the median (50th percentile), and the exterior lines denote 

the range in the data excluding outliers and extreme values (circles 

and asterisks, respectively, defined as observation >1.5 or >3 times 

the box length outside the box). Cover type acronyms and names (with 

number of point-count stations in parentheses): AC = Arizona cypress 

(4), PJ = pinyon – juniper woodland (25), MOW = Madrean oak woodland (17), PO = pine – oak forest (24), MC = mixed-conifer (10), and 

PP = ponderosa pine (9). Not shown is one plot in aspen forest (elevation = 2346 m).

forest was dominated by Arizona cypress, was generally restricted to riparian canyon 

bottoms, and occurred at the lowest elevations sampled. Three cover types primarily occurred at mid elevations: pinyon-juniper woodland was dominated by border 

pinyon and alligator-bark juniper, Madrean oak woodland was dominated by various 

oaks including silverleaf, Arizona white, and Emory oaks, and pine-oak forest was 

dominated by conifers such as Chihuahua and Apache pine along with Madrean oaks. 

Three additional cover types occurred primarily at higher elevations: (1) mixed-conifer 

forest, which was dominated by Douglas-fir and/or white fir, and sometimes contained 

Mexican white pine; (2) ponderosa pine forest, which was dominated by ponderosa or 

Arizona pine but sometimes contained other pines and Gambel oak; and (3) aspen forest, which was dominated by quaking aspen.
8 USDA Forest Service RMRS-GTR-368. 2017.

Figure 6—Examples of major forest cover types recognized. A. Aspen forest, B. Arizona cypress forest, C. Madrean oak woodland, D. Mixed-conifer forest, E. Pine-oak forest, F. Pinyon-juniper woodland, 

G. Ponderosa pine forest. Photo credits: Rocky Mountain Research Station (A); Jamie S. Sanderlin 

(B, C); Joseph L. Ganey (D–G).

A B

D

C
USDA Forest Service RMRS-GTR-368. 2017. 9

E

F

G
10 USDA Forest Service RMRS-GTR-368. 2017.

2012 Study

Early in 2012, we were contacted by concerned residents of the Chiricahua 

Mountains, including members of Friends of Cave Creek Canyon (2017) seeking 

information on how the 2011 Horseshoe II fire might impact the avifauna and local 

ecotourism. We shared information about the design of the RMRS study (1991 to 1995) 

and the resulting data with residents. We noted that the existing data set provided an 

opportunity to compare prefire data with postfire data, but that we lacked funding to 

collect postfire data.

Community leaders from Portal, Arizona, located at the eastern edge of the 

Chiricahua Mountains (fig. 3), expressed interest in conducting bird counts themselves 

if RMRS would assist with the study design and analysis. Consequently, we relocated 

the original eight transects established in 1991 using old topographic maps, transect 

descriptions, and pictures of point-count stations, and re-marked 89 of the 92 original 

point-count stations. We also provided the sampling protocols used in the 1991 to 1995 

study, trained citizen observers in point-count methodology and data collection, and 

agreed to analyze the data collected. The citizen group began conducting point counts 

in May 2012. Steep uneven terrain proved to be a major challenge, however, and only 

10 person days of sampling were accomplished during 2012 (table 2). Citizen observers 

remained interested in conducting point counts, but only if those counts could be conducted in less treacherous terrain.

Table 2—Survey effort by crew type and year. Citizen science observers struggled with 

the terrain on the original transects and completed fewer transects.

 Transect Number of Number of 

Year Crew typea typeb transects observers Person daysc

1991 RMRS O 6 3 18

1992 RMRS O 8 4 24

1993 RMRS O 8 2 16

1994 RMRS O 8 3 24

1995 RMRS O 8 6 24

2012 CS O 7 8 10

2013 CS N 8 8 18

2014 RMRS O 8 4 40

2014 RMRS N 8 4 18

a

 RMRS indicates surveys were conducted by bird crews employed by the U.S. Forest Service, 

Rocky Mountain Research Station. Citizen science (CS) indicates that surveys were conducted 

by skilled volunteer observers.

b

 O = original transect established in 1991 (counts were not completed on all of these transects in 

1991), N = new transect established in 2013.

c

 Calculated as number of transects surveyed by times each transect was surveyed by number 

of observers. Surveys from 1991 to 1995 were conducted by a single observer. Some transects 

were surveyed by single observers in 2012 and 2013, whereas others were surveyed using 

double observers. All 2014 surveys involved double observers.
USDA Forest Service RMRS-GTR-368. 2017. 11

2013 Study

Given continued interest by citizens in conducting point counts, we established a 

new set of transects early in 2013 that were on gentler terrain. Each new transect was 

located along a forest road or trail near an existing transect. We attempted to locate 

new transects in the same kinds of vegetation and topography as the original transects 

(fig. 7), to allow comparisons between the old and new data sets. New transects were 

shorter than the original transects, containing 6 to 11 point-count stations each (fig. 7). 

Feedback from citizen observers suggested that it would be more feasible to complete 

these shorter transects between sunrise and 4 hours after sunrise.

Figure 7—Juxtaposition of original and new transects used to sample bird populations in the Chiricahua Mountains 

in the 1990s and from 2012–2014, and burn severity around those transects estimated from data obtained from 

Monitoring Trends in Burn Severity (www.mtbs.gov) for the Horseshoe II fire, which burned in 2011. Some areas 

contained within the perimeter of this fire also burned in earlier fires, but severity data from those earlier fires was 

not summarized here. Colors represent burn severity classes: white = data missing for that area (due to cloud 

cover), light green = unburned to low severity, dark green = moderate severity, red = high severity. Point-count 

stations are represented by white squares or black circles for original and new transects, respectively. Pairs of 

transects are labeled A–H in upper left corner.
12 USDA Forest Service RMRS-GTR-368. 2017.

To evaluate how similar pairs of new and original transects were, we measured 

topographic characteristics and burn severity at all point-count stations on both original 

and new transects. We used a 30-m digital elevation model (DEM) to estimate elevation 

(m), slope steepness (deg), and slope aspect (or direction, deg) at each point-count station. We summarized burn severity around each point-count station using burn severity 

data from the most recent fire (2011 Horseshoe II fire). Burn severity data obtained 

from Monitoring Trends in Burn Severity (MTBS 2017) were summarized for a neighborhood of 0.81 ha (90 m x 90 m), centered on each point-count station. We recognized 

three burn severity classes: low, moderate, and high severity (fig. 8). In general, low 

burn-severity indicated less than 10 percent mortality in overstory trees and hence little 

structural change to dominant vegetation. Moderate severity reflected 10–70 percent 

mortality in overstory trees, with mortality in most areas less than 40 percent, and high 

severity ranged from greater than 70 to 100 percent tree mortality (Miller and Yool 

2002).
USDA Forest Service RMRS-GTR-368. 2017. 13

Figure 8—Examples of burn severity classes recognized. A. Two 

examples of areas that burned at low-severity in ponderosa pine forest. 

These sites show little change from prefire conditions. B. An example 

of a ponderosa pine site that burned with moderate severity. This area 

shows greater change than low severity sites, but still retains considerable overstory cover. C. Examples of areas that burned at high severity. 

Note the general absence of live overstory. Top: Mixed-conifer forest. 

Note abundant understory of bracken ferns (Pteridium spp.). Bottom: 

Madrean oak woodland. Note that many of the oaks lost all prefire 

live canopy but are still alive and are resprouting from the base of the 

trunk. D. Landscape view showing patches that experienced fire of differing severity. Photo credits: Jose M. Iniguez (A, B, C, top); Jamie S. 

Sanderlin (C, bottom); Will Jaremko-Wright (D; used by permission). 

A

B
14 USDA Forest Service RMRS-GTR-368. 2017.

C

D
USDA Forest Service RMRS-GTR-368. 2017. 15

We used Mann-Whitney tests (Conover 1999) to test for differences in elevation 

and slope between each pair of original and new transects, Watson-Williams tests (Zar 

2009) to compare aspect between paired transects, and chi-square tests (Conover 1999) 

to compare composition between original and new transects in terms of burn severity. 

We also summarized cover type composition for point-count stations on the original 

transects, using data on species composition and basal area collected during the 1990s 

(Iniguez et al. 2005). We did not complete vegetation sampling at point-count stations 

along the new transects, and thus cannot compare cover types between pairs of original 

and new transects.

2014 Study

We did not continue point counts by citizen observers in 2014, but instead hired an 

RMRS crew to conduct bird surveys with funding obtained from the Desert Landscape 

Conservation Cooperative (DLCC 2017). This crew sampled both sets of transects 

(original and new) in the Chiricahua Mountains. These data provided an opportunity 

to compare bird occupancy between pairs of original and new transects sampled by the 

RMRS bird crew in the same year (2014), and to compare point-count results between 

citizen observers (transects sampled in 2013) and RMRS crews (the same transects 

sampled in 2014).

Results and Discussion

Survey Effort

Rocky Mountain Research Station crews conducted 116 surveys from 1991 to 1995 

(table 2). Citizen observers began counting birds along original transects in May, 2012. 

Few counts were accomplished in 2012 due to terrain issues. The new transects were 

easier for citizen observers to navigate, and observers completed 80 percent more bird 

counts in 2013 than in 2012. RMRS crews sampled both sets (original and new) of 

transects in 2014.

Comparing Original and New Transects.

Elevation did not differ significantly (Mann-Whitney tests, P = 0.018 for transect G 

with all other P-values ≥0.261) between seven of eight pairs of original and new transects, suggesting that most new transects sampled were at the same general elevation 

belt as the original transects from the 1990s (fig. 9). The sole exception was new transect G (range = 2,338 to 2,423 m), which did not include the lowest elevations sampled 

by the original transect (range = 2,113 to 2,423 m). Slope steepness did not differ 

significantly between any pairs of original and new transects (all P-values ≥0.100; 

fig. 10). Slope aspect also did not differ significantly between any pairs of original and 

new transects (Watson-Williams tests, all P-values ≥0.217).
16 USDA Forest Service RMRS-GTR-368. 2017.

Figure 9—Elevation (m) of original and new transects used to 

sample bird populations in the Chiricahua Mountains, Arizona. 

Original transects were established in 1991, and new transects 

were established in 2013 along forest trails to facilitate surveys by 

citizens. The box indicates the range from the 25th percentile to the 

75th percentile, the solid line within the box indicates the median 

(50th percentile), and the exterior lines denote the range in the data. 

No significant differences were detected between any pairs of transects except for transect G.

Figure 10—Slope (deg) in original and new transects used to sample 

bird populations in the Chiricahua Mountains, Arizona. Original transects were established in 1991, and new transects were established 

in 2013 to facilitate surveys by citizen observers. The box indicates 

the range from the 25th percentile to the 75th percentile, the solid line 

within the box indicates the median (50th percentile), and the exterior 

lines denote the range in the data excluding outliers (circles, defined 

as observation >1.5 times the box length outside the box). No pairs of 

original and new transects differed significantly. 
USDA Forest Service RMRS-GTR-368. 2017. 17

Transects sampled a range of forest and woodland cover types, with the most 

frequently sampled types being pinyon-juniper woodland, ponderosa pine forests, 

and Madrean oak woodlands (fig. 11). Burn severity differed significantly among 

vegetation cover types (χ2

12 = 23.448, P = 0.024). Most cover types burned primarily at low to moderate severity, whereas ponderosa pine forest burned primarily at 

moderate to high severity and mixed-conifer forest burned primarily at high severity 

(fig. 12). Distributions of burn severity classes differed considerably among all transects (fig. 13), but the proportions of transects by burn severity class did not differ 

significantly between any pairs of original and new transects (chi-square tests, all 

P-values ≥0.097).

These results suggested that the new transects established in 2013 to facilitate 

surveys by citizen observers generally sampled the same range of ecological characteristics as the original transects, with the possible exception of transect G, which did 

not cover the lower elevations sampled by original transect G. Because cover type can 

vary with elevation, we compared cover types on the five original point-count stations 

at less than or equal to 2,338 m (the lowest elevation sampled by new transect G) to the 

distribution at the 7 original point-count stations greater than 2,338 m on transect G. 

Figure 11—Distribution (%) of point-count stations (n = 91) by forest and woodland cover types on the original transects established in 1991 to sample bird 

populations in the Chiricahua Mountains, Arizona. Cover type acronyms and 

names (with number of point-count stations in parentheses): AC = Arizona cypress 

(4), PJ = pinyon – juniper woodland (25), MOW = Madrean oak woodland (17), 

PO = pine – oak forest (24), MC = mixed-conifer (10), and PP = ponderosa pine 

(9). Not shown is one plot in aspen forest. Cover types were assigned based on 

species composition (% of basal area) sampled at point-count stations following 

Iniguez et al. (2005), but some types were renamed from Iniguez et al. (2005) to 

conform to more common naming conventions. All points were sampled before the 

2011 Horseshoe II fire, and cover type data were not available following that fire.
18 USDA Forest Service RMRS-GTR-368. 2017.

Cover type composition did not differ significantly between these groups (χ2

3 = 3.566, 

P = 0.312). This result, coupled with the general similarity between pairs of transects 

in terms of elevation, slope, aspect, and fire severity, suggests that pairs of original 

and new transects generally sampled similar cover types. Because bird populations 

and distribution are strongly related to vegetation type (Block and Brennan 1993; 

Hall et al. 1997), this suggests that pairs of original and new transects provide a good 

basis for comparing bird communities across time.

Bird Communities

Field crews detected 108 species of birds on transects sampled from 1991 to 1995 

and 96 species of birds on transects sampled from 2012 to 2014 (table 3). Twenty-one 

species of birds were detected from 1991 to 1995, but were not detected from 2012 to 

2014, and 12 species that were never detected from 1991 to 1995 were detected from 

2012 to 2014 (table 3).

Figure 12—Burn severity (% of point-count stations) by forest and 

woodland cover types on the original transects established in 1991 to 

sample bird populations in the Chiricahua Mountains, Arizona. Cover 

type acronyms and names (with number of point-count stations in parentheses): AC = Arizona cypress (4), PJ = pinyon – juniper woodland (25), 

MOW = Madrean oak woodland (17), PO = pine – oak forest (24), MC = 

mixed-conifer (10), and PP = ponderosa pine (9). Not shown is one pointcount station in aspen forest which burned at low severity. Cover types 

were assigned based on species composition (% of basal area) sampled 

at point-count stations following Iniguez et al. (2005), but some types were 

renamed from Iniguez et al. (2005) to conform to more common naming 

conventions. All vegetation sampling occurred before the 2011 Horseshoe 

II fire, and data on burn severity classes were obtained from Monitoring 

Trends in Burn Severity (www.mtbs.gov) for the Horseshoe II fire, which 

burned in 2011. Some areas contained within the perimeter of this fire also 

burned in earlier fires, but severity data from those earlier fires was not 

summarized here. 
USDA Forest Service RMRS-GTR-368. 2017. 19

Figure 13—Burn severity (% of point-count stations) on transects 

established to sample bird populations in the Chiricahua Mountains, 

Arizona. Data on burn severity classes were obtained from Monitoring 

Trends in Burn Severity (www.mtbs.gov) data for the Horseshoe II fire, 

which burned in 2011. Some areas contained within the perimeter of 

this fire also burned in earlier fires, but severity data from those earlier 

fires was not summarized here. Data summarized here includes all 

point-count stations from both original (established in 1991) and new 

(established in 2013) transects, because the distribution of severity 

classes did not differ between pairs of those transects. Number of 

point-count stations ranged from 16 to 23 for pairs of original and new 

transects.

Table 3—Birds detected during bird surveys on eight transects in the Chiricahua Mountains by 

time period. Birds are listed in taxonomic order, following the American Ornithologist’s Union 

Checklist of Birds of North and Central America (AOU 2017). One indicates the species was 

detected, zero indicates the species was not detected.

Common name Scientific name 1990–1995 2012–2014 Statusa

Gambel’s quail Callipepla gambelii 1 1

Montezuma quail Cyrtonyx montezumae 1 1

Wild turkey Meleagris gallopavo 0 1 U, Y

Turkey vulture Cathartes aura 1 1

Sharp-shinned hawk Accipiter striatus 0 1 NOC

Cooper’s hawk Accipiter cooperii 1 1

Northern goshawk Accipiter gentilis 1 1

Red-tailed hawk Buteo jamaicensis 1 1

Zone-tailed hawk Buteo albonotatus 1 0 NOC

Band-tailed pigeon Patagioenas fasciata 1 1

White-winged dove Zenaida asiatica 1 1

Mourning dove Zenaida macroura 1 1

Greater roadrunner Geococcyx californianus 1 1

Flammulated owl Otus flammeoulus 1 0 U, S

Whiskered screech-owl Megascops trichopsis 1 0 U, S

Great horned owl Bubo virginianus 1 0 NOC

Northern pygmy-owl Glaucidium gnoma 1 1

(continued)
20 USDA Forest Service RMRS-GTR-368. 2017.

Spotted owl Strix occidentalis 0 1 NOC

Mexican whip-poor-will Antrostomus arizonae 1 1

White-throated swift Aeronautes saxatalis 1 1

Magnificent hummingbird Eugenes fulgens 1 1

Blue-throated hummingbird Lampornis clemenciae 1 0 U, S

Black-chinned hummingbird Archilochus alexandri 1 1

Costa’s hummingbird Calypte costae 0 1 NOC

Broad-tailed hummingbird Selasphorus platycercus 1 1

Rufous hummingbird Selasphorus rufus 0 1

Broad-billed hummingbird Cynanthus latirostris 1 0 NOC

Elegant trogon Trogon elegans 1 1

Acorn woodpecker Melanerpes formicivorus 1 1

Ladder-backed woodpecker Picoides scalaris 1 1

Hairy woodpecker Picoides villosus 1 1

Arizona woodpecker Picoides stricklandii 1 1

Northern flicker Colaptes auratus 1 1

Prairie falcon Falco mexicanus 0 1 NOC

Thick-billed parrot Rhynchopsitta pachyrhyncha 1 0 NOC

Northern beardless-tyrannulet Camptostoma imberbe 1 0 NOC

Olive-sided flycatcher Contopus cooperi 0 1 NOC

Greater pewee Contopus pertinax 1 1

Western wood-peewee Contopus sordidulus 1 1

Hammond’s flycatcher Empidonax hammondii 1 1

Gray flycatcher Empidonax wrightii 0 1 U, M

Dusky flycatcher Empidonax oberholseri 1 1

Cordilleran flycatcher Empidonax occidentalis 1 1

Buff-breasted flycatcher Empidonax fulvifrons 1 1

Black phoebe Sayornis nigricans 1 1

Dusky-capped flycatcher Myiarchus tuberculifer 1 1

Ash-throated flycatcher Myiarchus cinerascens 1 1

Brown-crested flycatcher Myiarchus tyrannulus 0 1 C, S

Sulfur-bellied flycatcher Myiodynastes luteiventris 1 1

Cassin’s kingbird Tyrannus vociferans 1 1

Bell’s vireo Vireo bellii 1 0 NOC

Gray vireo Vireo vicinior 1 0 NOC

Plumbeous vireo Vireo plumbeus 1 1

Hutton’s vireo Vireo huttoni 1 1

Warbling vireo Vireo gilvus 1 1

Steller’s jay Cyanocitta stelleri 1 1

Western scrub-jay Aphelocoma californica 1 0 NOC

Mexican jay Aphelocoma wollweberi 1 1

Common raven Corvus corax 1 1

Violet-green swallow Tachycineta thalassina 1 1

Mexican chickadee Poecile sclateri 1 1

Bridled titmouse Baeoluphus wollweberi 1 1

Juniper titmouse Baeoluphus ridgwayi 1 1

Verdin Auriparus flaviceps 1 0 U, Y

Bushtit Psaltriparus minimus 1 1

Red-breasted nuthatch Sitta canadensis 1 1

White-breasted nuthatch Sitta carolinensis 1 1

Pygmy nuthatch Sitta pygmaea 1 1

Brown creeper Certhia americana 1 1

Rock wren Salpinctes obsoletus 1 1

Canyon wren Catherpes mexicanus 1 1

Table 3—(Continued).

Common name Scientific name 1990–1995 2012–2014 Statusa

(continued)
USDA Forest Service RMRS-GTR-368. 2017. 21

House wren Troglodytes aedon 1 1

Winter wren Troglodytes hiemalis 1 0 NOC

Bewick’s wren Thryomanes bewickii 1 1

Blue-gray gnatcatcher Polioptila caerulea 1 1

Golden-crowned kinglet Regulus satrapa 1 1

Ruby-crowned kinglet Regulus calendula 1 0 C, M

Western bluebird Sialia mexicana 1 1

Townsend’s solitaire Myadestes townsedii 1 1

Hermit thrush Catharus guttatus 1 1

American robin Turdus migratorius 1 1

Curve-billed thrasher Toxostoma curvirostre 1 0 U, Y

Northern mockingbird Mimus polyglottos 0 1

Cedar waxwing Bombycilla cedrorum 1 0 NOC

Phainopepla Phainopepla nitens 1 0 U, Y

Olive warbler Peucedramus taeniatus 1 1

Orange-crowned warbler Oreothlypsis celata 1 1

Nashville warbler Oreothlypsis ruficapilla 1 0 U, M

Virginia’s warbler Oreothlypsis virginiae 1 1

MacGillivray’s warbler Geothlypsis tolmiei 0 1 NOC

American redstart Setophaga ruticilla 0 1 NOC

Yellow-rumped warbler Setophaga coronata 1 1

Grace’s warbler Setophaga graciae 1 1

Black-throated gray warbler Setophaga nigrescens 1 1

Townsend’s warbler Setophaga townsendii 1 0 U, M

Hermit warbler Setophaga occidentalis 1 1

Wilson’s warbler Cardellina pusilla 1 1

Red-faced warbler Cardellina rubrifrons 1 1

Painted redstart Myioborus picta 1 1

Spotted towhee Pipilo maculatus 1 1

Rufous-crowned sparrow Aimophila ruficeps 1 1

Canyon towhee Melozone fusca 1 1

Chipping sparrow Spizella passerina 1 1

Black-chinned sparrow Spizella atrogularis 1 1

Dark-eyed junco Junco hyemalis 1 1

Yellow-eyed junco Junco phaeonotus 1 1

Hepatic tanager Piranga flava 1 1

Summer tanager Piranga rubra 1 0 U, S

Western tanager Piranga ludovicinia 1 1

Black-headed grosbeak Pheucticus melanocephalus 1 1

Lazuli bunting Passerina amoena 1 0 NOC

Brown-headed cowbird Molothrus ater 1 1

Scott’s oriole Icterus parisorum 1 1

House finch Carpodacus mexicanus 1 1

Cassin’s finch Carpodacus cassinii 1 1

Red crossbill Loxia curvirostra 1 1

Pine siskin Spinus pinus 1 1

Lesser goldfinch Spinus psaltria 1 1

Evening grosbeak Coccothraustes vespertinus 1 0 NOC 

a

 Status based on the 2016 checklist of common birds in Chiricahua National Monument (NPS 2016). 

Status is shown only for species that were detected in one time period but not the other. The first letter 

denotes abundance (C = common, U = uncommon), the second letter denotes season of occurrence (M = 

migratory [nonresident], S = summer resident, Y = year round resident). NOC denotes species that do not 

appear on the checklist, which shows “...the approximately 100 most common birds of Chiricahua National 

Monument...”.

Table 3—(Continued).

Common name Scientific name 1990–1995 2012–2014 Statusa
22 USDA Forest Service RMRS-GTR-368. 2017.

A few species that were detected during only one time period probably represented local colonization or extinction events. For example, thick-billed parrots were 

detected during a failed reintroduction effort during the 1990s but not from 2012 to 

2014 (Snyder et al. 1994, 1995), and this species likely is extinct in the Chiricahua 

Mountains at this time (Corman and Wise-Gervais 2005). In contrast, the wild turkey 

was reintroduced to the Chiricahua Mountains following the 1990s survey period (NPS 

2006).

Most other species that were detected during only one decade were species that 

were detected infrequently, either because they were relatively uncommon or because 

their typical activity period did not greatly overlap with our bird surveys (for example, 

owls). For these species, detection during only one decade may or may not indicate 

local colonization or extinction events, and additional years of monitoring will be 

 required to distinguish between these hypotheses.

Future Directions

Several important steps remain in designing and implementing a rigorous but costeffective avian monitoring program in the Sky Islands. First, to make valid comparisons 

between pre and postfire avian count data, we need to verify that original and new transects provide a good basis for comparing bird communities. To address this question, 

we are currently using single-season, multi-species occupancy models (MacKenzie 

et al. 2006; Royle and Dorazio 2008: 384–87) in a Bayesian hierarchical framework 

(Gelman et al. 2004) to compare bird communities sampled in 2014 by RMRS crews 

along both the original and new transects.

Second, to continue using citizen observers to monitor avian populations and to 

allow valid comparisons between data collected by citizen observers and by RMRS 

crews, we must verify that detection probabilities are estimable. To address this 

question, we are currently comparing data collected on the new transects by citizen 

observers (in 2012 and 2013) and RMRS crews (in 2014) using multi-season, multispecies occupancy models (MacKenzie et al. 2006; Royle and Dorazio 2008: 384–387).

Third, we need to comprehensively evaluate the strength of potential observer 

effects (both individuals and type; i.e. citizen observer vs. RMRS crew), as well as the 

potential effects of transect type (original vs. new) on estimates of detection probability, 

occupancy, species richness, and local extinction and colonization probabilities. This 

evaluation is in progress, again utilizing multi-species occupancy models in a Bayesian 

hierarchical modeling framework. And fourth, we need to use the results of these analyses to design a rigorous but cost-effective monitoring program using citizen observers.

The above analyses relate only to the scientific or technical aspects of designing 

this monitoring program. Our experience suggests that there are considerable human 
USDA Forest Service RMRS-GTR-368. 2017. 23

challenges to overcome as well (e.g., Barrows et al. 2016; Cox et al. 2012; Tulloch 

et al. 2013). Chief among these is identifying a cadre of suitable observers willing and 

able to conduct surveys. The work is difficult, people are busy with their lives and 

work, and it is difficult to find volunteers who will dedicate time to such work both 

within and especially among years. This problem is exacerbated in our case because 

of the inherent difficulty in conducting point counts for birds, the difficult terrain 

involved, and safety issues related to working in mountains along the border with 

Mexico. Citizen observers conducting point counts must be able to navigate difficult 

terrain and identify birds by sight and sound, and many observers simply do not possess the necessary skills. Further, some observers who do possess those skills may be 

unwilling to work in difficult terrain near the border subject to traffic by drug smugglers and migrants entering the U.S. illegally.

These aspects make this study fundamentally different from other citizen science 

efforts such as eBird (2017) or the Breeding Bird Survey (BBS 2017), two prominent 

broad-scale efforts that present far fewer challenges to citizen observers. Many BBS 

routes occur along roads or trails, and have fewer sample points. Similarly, eBird 

has variable sample efforts. Both BBS and eBird focus on broad-scale trends in bird 

populations, and do not require as much detail as the fine scale needed in this study to 

evaluate fire effects on bird populations in one mountain range.

Assuming that interested citizen observers are available, a second challenge is 

coordinating and scheduling surveys. Our experience suggests that such coordination 

is critical to success, and would best be accomplished with an on-site coordinator 

position. We developed a website (Arizona Sky Island Birds 2017) to increase communication about this program and enhance involvement, but more direct outreach likely 

is required for the project to succeed. Such outreach might consist of regular meetings 

and presentations about the project to maintain enthusiasm for participation, and identifying creative ways to reward participants and acknowledge that their contributions 

are highly valued. Involving a social scientist with expertise in working with citizen 

observers could improve this aspect of the study.

Finding suitable observers is further complicated by the relatively sparse human 

population residing in the Chiricahua Mountains. Because the number of local residents 

is limited, it would be helpful to draw on citizen observers from outside the Chiricahua 

Mountains to broaden the potential pool of observers. Many such individuals would 

have to travel considerable distances to conduct sampling in the Chiricahua Mountains 

(and other Sky Islands), and funding to reimburse observers for travel costs would be 

invaluable. Because the point counts require observers to begin at or near dawn, citizen 

observers also may need to spend the previous night near transects to be sampled. The 

ability to provide housing for citizen observers in the vicinity of transects would also be 

invaluable.
24 USDA Forest Service RMRS-GTR-368. 2017.

Clearly, paying a coordinator, providing training, housing, and reimbursing citizen 

observers for their costs raises the cost of conducting the monitoring. The reality, 

however, is that conducting this type of sampling in this type of terrain is difficult 

work. Expecting observers to remain involved over time without providing training, 

coordination, and some level of oversight, and without fair compensation, is unrealistic. 

Consequently, some level of consistent funding will be required to support a successful 

monitoring program.

Conclusions

We identified a potential mechanism for involving skilled citizen observers in an 

ongoing program to monitor communities of forest and woodland birds in the Madrean 

Sky Islands. We also demonstrated that our newly designated transects sample physical 

environments similar to those sampled by our original transects. Preliminary results 

suggest that designing a rigorous program involving these citizen observers may be 

feasible, but a number of technical and human challenges remain to be overcome. For 

valid comparisons with prefire data, we must demonstrate that we are sampling the 

same bird communities with the new trail points and the original points. Other technical 

challenges include quantifying potential observer and transect effects on community 

parameters, so that a cost-effective monitoring program could be developed with citizen 

observers. Human challenges include finding a skilled and dedicated group of observers, coordinating surveys and observers, and maintaining project participation through 

outreach activities.

These aspects present significant challenges, but we believe that this approach has 

great potential for accomplishing otherwise impossible data collection in an era of 

shrinking research budgets. We further believe that many citizens are keenly interested 

in this type of work and searching for opportunities to contribute and that engaging 

these citizens has benefits that extend far beyond accomplishing additional data collection. Involving citizens can increase their understanding of and appreciation for 

conservation science, foster greater appreciation for the land management agencies 

involved in conservation and the difficulty of their mission, create incentives for 

citizens to work in the field, and generally leave participating citizens with a sense of 

accomplishment. For all of these reasons, we believe that our effort to overcome these 

challenges is a worthwhile endeavor.

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