2019 Chihuahuan Desert Conference Session 2 – Abstracts and Bios

Session 2 – Birds

Topic: Potential effects of climate change on the El Paso bird community

Presenter: Dr. Kevin Floyd.  Contributor, John Sproul, University of Texas at El Paso

Session Abstract: The southwestern United States is expected to become warmer and drier under most climate change scenarios.  Plant and animal species are projected to move, if possible, to track the climate to which they have adapted.  A 2015 study by the National Audubon Society found that almost half of North America’s bird species are expected to lose >50% of their current range, with 40% of those species not able to find appropriate new habitats.  Termed “climate endangered,” these species include Swainson’s hawks, burrowing owls, and rufous hummingbirds, birds that are resident or migratory in El Paso.  Although those projections are for 2050 and 2080, we are currently seeing occurrence patterns change in our bird community, as reported by community scientists via eBird.org.  Species which used to migrate south of El Paso in the winter, including turkey vultures, black-necked stilts, American avocets, and cave swallows, are now regularly seen most of the year.  Arrival dates for other species, such as western kingbirds and yellow-breasted chats, have shifted earlier in the spring.  Rarely seen species, such as northern cardinals and tropical kingbirds, have expanded into the region, with documented breeding here by both species in 2019.  It is likely too soon to determine what will happen to the local bird community, as that depends on what climate change mitigation efforts are taken, and how soon.  Current distributions are needed to build accurate projections, and we encourage all bird watchers to submit their observations to eBird.org, making them available to the scientific community.

Kevin Floyd received his B.S. and M.S. degrees from the University of California at Davis before moving to El Paso.  He completed his Ph.D. in Environmental Science and Engineering at UTEP studying how roads impact lizard populations.  He is currently a lecturer in the Department of Biological Sciences at UTEP and Assistant Botanical Curator at the Chihuahuan Desert Gardens.  Kevin is an avid birder and serves as conservation chair for the El Paso/Trans-Pecos Audubon Society.


Topic: Population Genomics Reveals Low levels of Hybridization between Mallards and Mexican Ducks

Presenter: Joshua I. Brown. Contributor: Philip Lavretsky

Session Abstract:  Little is known about the evolutionary history of the Chihuahuan desert endemic Mexican duck (Anas platyrhynchos diazi), which is one of fourteen Mallard-like ducks within the Mallard Complex. Hybridization with mallards (A. platyrhynchos) was originally thought to be a major conservation concern for Mexican ducks, but recent molecular work suggests otherwise. Here, we use a landscape level approach to determine the extent of current hybridization between mallards and Mexican ducks. We collected a total of 266 Mexican ducks across their range, 70 mallards, as well as 62 domestic mallards, including feral Khaki Campbell and game-farm released mallards from three states. We sequenced ~3,500 ddRAD-seq nuclear loci across samples, and report that mallards and Mexican ducks are genetically structured, and that Mexican duck populations follow an isolation-by-distance pattern. Notably, despite previous estimates of wide-spread hybridization, we report that hybridization between Mexican ducks and mallards (wild or domestic) is generally rare, and lowest of all New World Mallard-like ducks. In fact, we propose that previous estimates of hybridization based on plumage alone were likely inaccurate because traits thought to indicate a hybrid were in fact ancestrally shared between Mexican ducks and mallards. Moreover, several genomic regions under the effects of divergent selection within either Mexican ducks or mallards were recovered, providing support for the possible evolution of isolating mechanisms between the two. Next, we find that Mexican duck populations established in the early 1990’s, and now distributed throughout western coastal habitats of Sonora and Sinaloa, were founded by Mexican ducks from Chihuahua.

About Joshua I. Brown: I have been hunting since I was 6 years old, and with this I have developed a passion for the outdoors and wildlife conservation. This passion is what has motivated me to pursue a PhD degree in Biological sciences specifically focusing on waterfowl population genetics. For my PhD research project, I will be using Next Generation Sequencing techniques to look at movement patterns and hybridization of Mexican ducks and New Zealand Grey ducks. I am personally interested in integrating next generation genetic methods with traditional ecology to better inform waterfowl management and conservation plans throughout North America.


Topic: Urban Nesting Ecology, Site Selection, and Monitoring of Burrowing Owls in the Northern Chihuahuan Desert

Presenter: Lois Balin

Session Abstract: Urbanization of the desert southwest is rapidly encroaching Western burrowing owl (Athena cunicularia hypogea) habitat. Texas Parks and Wildlife initiated a long-term descriptive study at Rio Bosque Wetlands Park in El Paso, Texas.  Objectives were to determine factors influencing nest site selection, design artificial den sites to aid in burrowing owl restoration, and to monitor owls in artificial and natural nest sites with infra-red, trail, and burrow cameras.  Beginning in 2012 various artificial nest site designs were installed and owls were monitored for nest site selection and nesting ecology. Owls were captured and banded to determine nest-site fidelity.  From 2013 to 2018, 31.3% of 147 owls banded returned for an average of 7.67 owls per year. General use of artificial nest sites by nest box material and number of burrows varied.  A total of 52 nesting and 37 fledgling events occurred from 2013-2019. Nesting occurred 50% of the time in barrels, 19% in natural burrows, 17% in 5-gal buckets, and 13% in irrigation boxes. Having filled in with soil, no nesting occurred in natural burrows since 2018.  In urban areas owls often inhabit manmade structures. Burrowing owls used available artificial sites to potentially conserve energy, despite being able to dig their own burrows. The owls preferred nesting in barrels with one burrow, however, predation within the nest caused complete or partial nest failure 9.6% of the time.  In predator dense areas, nest sites with 2 entrances are recommended to provide an escape route from predators entering the nest box.

Lois Balin is the West Texas Urban Wildlife Biologist for the Texas Parks and Wildlife Department, based in El Paso now for 20 years.  Lois received her B.S. in Wildlife and Fisheries Science at the University of Arizona and her M.S. in Range and Wildlife Science at Texas A&M, Caesar Kleberg Wildlife Research Institute.  Her professional work includes providing technical guidance on sensitive urban development and management for the City and County of El Paso, promoting biodiversity, providing educational programs and resources on wildlife, ecology, native plant landscaping, habitat and conservation-related issues, and conducting wildlife research on burrowing owls.  She served 8 years on the City of El Paso’s Open Space Advisory Board, 2 has Chair and is the State Advisor to the local Trans-Pecos Chapter of the Texas Master Naturalist Program. 


Topic: Landbird Monitoring in the Chihuahuan Desert

Presenter: Jessica Colbaugh. Contributors: Robert Gitzen, Melissa Powell, Patty Valentine-Darby, Greg Levandoski

Session Abstract: The Inventory and Monitoring Division has been monitoring national parks within networks using vital signs to detect changes within parks. This presentation focuses on the Chihuahuan Desert Network (CHDN) and birds as a vital sign. After the first few years of data collection, species richness, composition, and abundance analyses were completed as a part of preliminary analysis to assess effort and quality of estimates. We describe results of these analyses in addition to recommendations for monitoring in the future. Species richness was analyzed using a first-order jackknife estimator. Species composition was based on grouping species into habitat guilds using primary habitat preference. Abundance was assessed through density analysis using Distance sampling. All analyses were run for each combination of park in CHDN, year (2010-2017), and upland/riparian habitat for which data was collected. Guadalupe Mountains National Park upland, Carlsbad Caverns National Park riparian, and Amistad National Recreation Area upland areas had the largest ranges in raw species richness over years. For species composition the proportion of species in each habitat guild were averaged over years and parks. In park uplands, shrubland species had the largest average proportion (36%) and grassland/savannah species were only 11% of species. In riparian areas woodland species had the largest average proportion (27%). Density was calculated for a limited number of species per park due to sample size needs. Recommendations for future monitoring focus on improvements in uncertainty and bias and overall efficiency through changes in timing of sampling.Jessica Colbaugh is a master’s student at Auburn University pursuing a degree in Wildlife Sciences. Her thesis project is focused on evaluating landbird monitoring options to best suit objectives. She received a Bachelor of Science from the University of Minnesota-Twin Cities. Her field work experiences have focused on investigating habitat availability, invasive species influence on community dynamics, and effectiveness of different management actions through wetlands mapping, avian surveys, nest searching, and aquatic and terrestrial plant surveys. Her research topics of interest are community dynamics, invasive species, birds, plants, and wetlands.


Topic: Birds of Juniper and Oak Scrubland in Trans-Pecos With Notes on the Elf Owl and Oslar’s Oakworm Moth

Kayla R. Garza

Session Abstract: Indio Mountains Research Station (IMRS) in west Texas has been a learning and research-intensive site for decades. Birds have been casually documented throughout its management and during research projects. Birds and other organisms in most of Trans-Pecos are not well represented in the literature outside of Big Bend. We studied the Elf Owl’s (Micrathene whitneyi) life history, birds utilizing juniper and oak habitats in the scrublands, and use of vegetation by moths and butterflies. Micrathene whitneyi were documented via camera-trap installed on a water tank structure at IMRS Headquarters from 2013-2014, with general documentation occurring from 2010-2019. A study conducted from 2016-2018 within juniper and oak habitats provided data on year-round, migrant, breeding, and wintering bird species on IMRS. During this study, butterfly and moth species were identified, and some monitored on host plants. Results included M. whitneyi vertebrate diet additions, including the Texas Banded Gecko (Coleonyx brevis) and Ornate Tree Lizard (Urosaurus ornatus), and their range extending farther into the Trans-Pecos than previously documented. Findings also included bird use of Quercus and Juniperus trees for nesting, migrant stop-over use, individuals found outside of their documented range, and wintering birds using the habitat. Oslar’s Oakworm Moth (Anisota oslari) was documented using Sandpaper Oak (Quercus pungens) as a host plant, and the Common Nighthawk (Chordeiles acutipennis) was documented preying on A. oslari during summer breeding in the habitat. Continued collection of natural history data on IMRS can provide valuable data to professionals implementing land and wildlife management plans in the future.

Kayla R. Garza: Raised in El Paso, Texas I began college at El Paso Community College in 2010 and earned an Associate of Science in Biology. In 2012, I attended the University of Texas in El Paso studying ecology and evolutionary biology, was admitted into the National Science Foundation’s (NSF) Chihuahuan Desert Research Experience for Undergraduates (CDB-REU), presented my research at several conferences at home and abroad, got married to my amazing husband in 2014, and earned a Bachelor of Science in 2015. In 2016, I was accepted into UTEP’s graduate program in Biological Science and conducted an 18-month study on birds using juniper and oak ecosystems in the Chihuahuan Desert. I published research in the Herpetological Review entitled, “Necrophilia and Feeding Behavior in the Ornate Tree Lizard (Urosaurus oranatus)”. I successfully defended my thesis May 2018 and gave birth to my son, who is now 13 months old, in July. Fall of 2018, I published research in the Southwestern Entomologist entitled, “First Record of Anisota oslari from Trans-Pecos, Texas Using Sandpaper Oak as a Host”. Spring 2019, I completed a comprehensive avian atlas for use by students and researchers, and in fall 2019 submitted a manuscript on the life history of the Elf Owl to the Southwestern Naturalist entitled, “Elf Owl (Micrathene whitneyi) breeding records and habitat selection on Indio Mountains Research Station, Hudspeth County, Texas”. I currently live in Lawrence, Kansas with my lovely family where I’m working on a Graduate Certificate in Environmental Assessment at KU.


Topic: The El Paso Zoo’s Raptor Rehabilitation Program

Presenter: Dr. Misty Garcia

Session Abstract: The El Paso Zoo Animal Medical Center provides medical care to almost 200 wild raptors each year. The goal of the program is to release birds back to the wild; however, on some occasions non-releasable patients are transferred to educational programs or other zoos. Typical species treated include Swainson’s hawks, red-tailed hawks, burrowing owls, great horned owls, and kestrels. Less frequently vultures, golden eagles, peregrine falcons, and Mississippi kites are encountered. The region serviced typically extends from Silver City, NM to Marfa, TX. Birds are brought in by animal control, wildlife rehabilitators, Texas Parks and Wildlife, and members of the public. Injuries due trauma such as fractures, gunshot wounds, head injuries, and electrocution are most frequently seen as well as infectious diseases such as West Nile virus and trichomoniasis. Also commonly received are nestling and fledgling birds. Birds are treated at the El Paso Zoo with eventual transfer to Gila Wildlife Rescue, the closest raptor rehabilitation center to the city of El Paso, where raptors relearn to fly and hunt. For the current year, 2019, all birds except for one patient that have been transferred to Gila Wildlife Rescue have been successfully rehabilitated and released to the wild.

Dr. Misty Garcia is a veterinarian at the El Paso Zoo. An El Paso native, she received a Bachelors of Arts degree at Carleton College in Northfield, MN and a Doctor of Veterinary Medicine at the University of Wisconsin-Madison. Dr. Garcia began her zoo veterinary career at the Dallas Zoo followed by the Abilene Zoo. She returned to her home city and has been at the El Paso Zoo for six years.


Topic: Bendire’s Thrasher Nest Survival in Relations to Vegetation Characteristics in the Southwest United States

Presenter: Allison Salas. Contributors: Martha Desmond, Fistum A. Gebreselassie, Department of Fish, Wildlife and Conservation Ecology, New Mexico State University

Session Abstract: Arid land birds are among the fastest declining avian assemblage, however, little is known about species that reside in the southwestern United States. To enhance our fundamental understanding of the breeding biology of Bendire’s Thrashers (Toxostoma bendieri), we must identify key vegetation characteristics associated with the nesting period, document common nest predators and examine if interspecific competition occurs with other mimids. One objective of this study is to examine nest survival in relation to local and landscape variables. We located and monitored nests (n=75) until fledging or failure during the breeding seasons of 2018 and 2019. There were 43 nests that successfully fledged young between the two years of data collection, with predation being the main cause of nest failure. The most common predator species documented was Chihuahuan Ravens (Corvus cryptoleucus), as well as coyotes (Canis latrans), Javelina (Pecari tajacu) and rodents. The preliminary daily survival estimate from the top nest survival model was 0.97 (SE=0.01) and the cumulative nest survival rate was 0.44 (SE=0.06), assuming a 22-day breeding attempt. Preliminary model results at the nest site scale show that important predictor variables for survival include day of the breeding season, nest age, year, and nest height. All of the top five models were significant, as 95% CIs did not bound 0. Future analysis will examine vegetation characteristics at a broader scale, including at the territory and landscape, in addition to food abundance and climatic variables that may also be affecting nest survival.Allison Salas is a graduate student at New Mexico State University under advisor Dr. Martha Desmond within the Department of Fish, Wildlife and Conservation Ecology. Originally form Florida; she received her Bachelors of Science from the University of Maryland. Her passion for studying birds and conversation has taken her all over the country as well as Canada, Jamaica and Belize.


Topic: Educating about the Chihuahuan Desert using birds of prey

Presenter: Heather Rivera

Session Abstract: The Chihuahuan Desert is an ecoregion with a vast diversity of life. It is home to many species of plants, mammals, reptiles, invertebrates and birds. While all this life surrounds the region, many individuals still have a difficult time feeling connected to this desert. The El Paso Zoo Education Department is committed to teaching adults and children about the Chihuahuan Desert and how to conserve it.  Through the Education Animal Ambassador program, the El Paso Zoo has been able to give guests a close up encounter with some of the desert’s most important inhabitants, birds of prey.  Since 2010, the El Paso Zoo has used birds of prey to educate our guests about the animals in the Chihuahuan Desert. This began with Takota, a visually impaired Golden Eagle. In March 2010, Takota began visiting with guests during public programs and made appearances at several off grounds programs. Some notable appearances were at the Franklin Mountains Poppy Festival, Music Under the Stars and at “An Evening with Jack Hanna” where he was one of the featured animals on stage. Other birds of prey were later added to the Education department collection in the following years. These birds have included a Harris’ hawk, Swainson’s hawk and a Burrowing owl.  With these birds, the El Paso Zoo Education department has been able to connect El Pasoans with nature as well as teach them how to protect our natural resources.

Heather Rivera is an Education Specialist with the El Paso Zoo Education department. She has been working with birds of prey since June 2010 as their main presenter, keeper and trainer. She is also in charge of the El Paso Education Animal Handling team where she teaches volunteer on staff on how to work with Education animal collection.


Topic: Prey composition of Western Burrowing Owls during the nesting season at Rio Bosque  Wetlands Park, El Paso, Texas

Presenter: Walter G. Flocke. Contributors: Thomas S. Janke, Borderlands Research Institute, Richard D. Heilbrun, Lois Balin Texas Parks and Wildlife Department 

Session Abstract: Burrowing owls’ (Athene cunicularia) native habitat and nest sites are declining; however, this species is capable of inhabiting urban environments and non-traditional nest sites (e.g., artificial nest boxes or burrows) in place of natural ones.  From 2009 – 2019, Texas Parks and Wildlife Department constructed artificial nesting sites (n = 26) at Rio Bosque Wetlands Park in El Paso, Texas to create additional suitable nesting habitat for the conservation of this species.  Two of the artificial nest sites were fitted with underground infrared-video cameras in 2014.  In 2019, one of the artificial nesting sites with infrared cameras was utilized by a pair of burrowing owls during the nesting season (March – August).  The objective of this study was to identify and quantify prey items that the burrowing owl pair brought into the artificial nest box during the nesting season.  All cameras (1 in each of the 2 burrows, and 1 in the main nest box) collected infrared video footage from 1 April – 5 July 2019.  We monitored video footage to identify prey items delivered into the burrows and nest box.  Our ability to identify prey species to various taxonomic levels (i.e., order, family, etc.) was influenced by the quality of imagery and by the taxa delivered.  Out of the prey items documented (n = 516), invertebrates made up the majority (>60%) brought to the nest site.  This study will ultimately add to the understanding and management for conserving this species.

Walter Flocke: I was born and raised in the Texas Hill Country in the community of Wimberley.  Growing up there, I was inspired by the wildlife of the area, particularly birds, and I picked up birding at an early age.  I was also concerned by the rapid subdividing of land and urban development rising around me.  I decided to attend Sul Ross to learn the methods for protecting and conserving the wildlife I grew up with for future generations to enjoy.  I am now a senior at Sul Ross State University studying wildlife management.  At Sul Ross I have grown involved in the conservation of the Chihuahuan Desert through involvement in the Range and Wildlife Club Plant ID team, participating in wildlife captures, and working for the Borderlands Research Institute (BRI) as a technician on a mesocarnivore camera trap study in Big Bend National Park.  I am now working in cooperation with the Texas Parks and Wildlife Department (TPWD) on an urban wildlife study of burrowing owls in Rio Bosque Wetlands Park, in El Paso, Texas.  This study has been very fulfilling, and I feel honored to be a part of this unprecedented research project for BRI and TPWD.  I hope to continue working with wildlife after graduation as a member of a land conservation agency or organization working towards conserving species holistically at the landscape level.

Topic: Effects of translocation on burrowing owl survival and reproduction in Arizona

Presenter: Dejeanne Doublet. Contributors: Martha J Desmond, Fitsum Abadi, New Mexico State University and David H Johnson – Global Owl Project

Session Abstract: Monitoring post-release outcomes of translocated animals provides vital insight that can help biologists design more effective release programs for species of concern. We monitored outcomes of a burrowing owl (Athene cunicularia) translocation program in Arizona, where hundreds of owls are relocated each year from construction zones to new sites that contain artificial burrows. After a captivity period, the owls are soft-released in temporary tent enclosures in groups of 10 owls/tent from April – May. Our objectives were to (1) compare survival and nest survival of translocated and resident burrowing owls and (2) determine factors that influence the survival of translocated owls (i.e. captivity duration, nearby owl density, and the number of males/release group). From 2017 – 2019, we used VHF radio-telemetry to determine the fates of 85 owls (43 translocated, 42 resident) across four release sites. We examined nest survival of 129 nests of translocated and resident owls during the 2017 and 2018 breeding seasons. Results indicated that translocated owls had lower annual survival (0.35±0.08) than resident owls (0.80±0.07). Cumulative nest survival was also lower for translocated owls than for resident owls (0.21±0.06 and 0.76±0.06, respectively). Survival of the translocated owls was negatively correlated with the number of males/release group and with captivity duration. We, therefore, recommend releasing owls individually or as pairs as to avoid potential conflict between territorial males in the enclosures. Releases should be conducted in the fall and winter months to minimize captivity duration and allow the owls more time to establish territories prior to the nesting season.

Dejeanne Doublet is an El Paso native who is currently a graduate student at New Mexico State University studying Wildlife Science. She conducts research on the effects of translocation on Burrowing Owls in Arizona. Before grad school, Dejeanne received her bachelor’s degree in Environmental Science from Boston University and worked with organizations such as the Smithsonian Institute and the National Park Service. After graduation, she plans to work in conservation in the Chihuahuan Desert.

Topic: Standardizing hybrid identification: Developing a genetically-vetted field key to distinguish between Mexican ducks, mallards, and their hybrids

Presenter: Flor Hernández. Contributors: Andrew Engilis Jr., Josh I. Brown, Alexis Díaz, Philip Lavretsky

Session Abstract: Hybridization rates between the Mexican duck and mallards were previously based on plumage characteristics only. However, traits among Mallard-like ducks that appear to be indicative of a hybrid may, in fact, be ancestral. Thus, using phenotypic characters alone may be inaccurate for estimating hybridization rates. Instead, we outline steps and present the first genetically vetted phenotypic scoring key that can be used to accurately identify Mexican ducks and hybrids in the field. We documented 22 plumage characteristics for samples that are also genetically vetted as pure or hybrid for 213 Mexican ducks across their ranges in the US and Mexico, as well as mallards from North America. In short, samples are first genetically assigned as pure (i.e., ≥95% genetic assignment to one group) Mexican duck, pure mallard or hybrid (i.e., ≥10% genetic assignment to the interspecific group). Next, we perform a discriminant function analysis to determine which phenotypic characters best distinguish between genetically assigned pure Mexican ducks, pure mallards, and hybrids.  Among sex-age classes, we report that first-year male Mexican ducks commonly exhibited mallard-like traits not observed in adult males. Moreover, the expression of these traits in first-year male Mexican ducks decreased from their northern to the southern range. This finding may explain early reports of decreasing hybrid prevalence with the same clinal fashion. Additionally, we corroborate earlier reports that female Mexican ducks show subtle plumage traits that make them difficult to distinguish from hybrids. Though juvenile males and females may be problematic to separate from hybrids, the accuracy of the key increases with adult individuals.

Flor Hernández: I was a Peruvian ornithologist for 9 years where I studied the ecology of various bird species though banding programs throughout Peru. My interests range from understanding species spatial diversity and distribution to overall population dynamics, parasite ecology, and foraging behavior. Moreover, I have worked in various museums where I have specimen prepared close to 1000 specimens. In 2018, I joined the Lavretsky Lab at UTEP and started my PhD in the Ecology and Evolutionary Biology department. My dissertation focuses on the genomes of various taxa within the recently radiated Mallard Complex. I will be using a combination of whole genome re-sequencing and partial genome sequencing to understand how various evolutionary mechanisms interact at the earliest stages of species divergence. In addition, I will be performing association tests to determine the genetic variation that underlie phenotypic variance among taxa. In addition to answering more broad evolutionary questions, I will apply my findings towards the conservation and management of these species.