HOW STABLE ARE HYBRID ZONES IN THE FACE OF CLIMATE CHANGE?
|Daniel K Pierce; University of California Riverside; firstname.lastname@example.org; Alan Brelsford
Hybrid zone stability depends on a balance between dispersal into the hybrid zone and selection against hybrids. Environmental change can influence dispersal and selection and lead to displacement of a hybrid zone, so a moving hybrid zone may indicate ecologically and evolutionarily important environmental change. We examine a historically stable hybrid zone between Audubon’s and myrtle yellow-rumped warblers to determine if a recent Mountain Pine Beetle outbreak has had an effect on the location of this hybrid zone. The mountain pine beetle outbreak west of the Canadian Rocky Mountains has led to the degradation of much of the yellow-rumped warbler breeding habitat, primarily in the region occupied by Audubon’s warblers. Using geographic clines in genetic data from over a thousand yellow-rumped warblers sampled across 16 years, we estimate the historical and contemporary positions of the hybrid zone. By comparing the location of the hybrid zone between time periods at four transects that differ in severity of the mountain pine beetle outbreak, we assess this hybrid zone's stability and discuss the potential for climate change to influence species boundaries.
PRELIMINARY RESULTS OF A POPULATION ASSESSMENT FOR LEAST BELL'S VIREOS, VIREO BELLII PUSILLUS, IN THE SANTA CLARA RIVER VALLEY IN SOUTHERN CALIFORNIA
|Andrew J. Dennhardt; U.S. Fish and Wildlife Service; email@example.com; Danielle A. Clearwater, Chris Dellith
Estimating population abundance is fundamental to species conservation. Conservation of threatened and endangered species, in particular, necessitates evaluation of quantifiable criteria to advance, and ultimately achieve, recovery. For instance, the draft Recovery Plan for the federally endangered least Bell’s vireo (Vireo bellii pusillus) recommends that downlisting to threatened status may be achieved when stable or increasing populations, each consisting of several hundred or more breeding pairs, are both protected and managed during five consecutive years across vireo metapopulation areas. One such area includes the Santa Clara River Valley of southern California. At present, the U.S. Fish and Wildlife Service and its partners are piloting a multi-year, point-count study of least Bell’s vireos across the valley study area. Our population assessment follows a dependent, double-observer sampling approach to enhance observer detection of vireos during repeat survey visits between 80 (spring 2021) and 104 (spring 2022) sites. While controlling for ecological- and observational-process variation, we analyzed preliminary vireo counts using single-season N-mixture models and estimated that hundreds of breeding pairs currently occupy the valley, which begins to evaluate recovery criteria and demonstrates the utility of standardized, stratified-random surveys to evaluate vireo population quantities and recovery outcomes across its range.
DECADES OF RIPARIAN BREEDING BIRDS SHOW PERSISTENT REDUCTION AFTER EXTREME HEAT
|Dave L Riensche; firstname.lastname@example.org;
Historical records show that diverse Canaries in our “coal mine” environment generally have been disappearing, despite protections. Since 1994, we have been conducting periodic, consistent breeding bird censuses in a protected riparian area on San Francisco Bay’s east (downwind) shore, relatively stable in local weather and vegetation. We detected an overall decline in breeding birds there, hypothetically corresponding to steadily increasing human activity in adjacent areas. Yet bird declines were not steady at all. Reports of unusually warm, calm weather around San Francisco Bay in 2004, and unusually warm, humid weather in 2006 prompted us to compare these old and newer bird data to weather records, which also illustrated a 2000 heat event locally. To test hypothetical effects of these unusual heat events of 2000/2004/2006, we compared bird data before and after those years, yielding a clear, persistent reduction in most breeding avifauna, after those events. Annual Maximum temperatures also became repeatedly >36 degrees C, which might be a threshold for many of these birds. Such heat again in 2017 did not appear to decrease these bird populations further. Historical data from 1973 suggested >34% more territories there, but only minor subsequent heat through our 1994- data, illustrating additional limits on these birds. Trends in comparing general weather and breeding bird data might not be clear in such coastal, relatively benign climates, within birds’ adaptations. Yet occasional, extreme environmental events, particularly in a protected area avoiding much habitat degradation, appears to have additional major negative, lasting effects on these breeding populations.
ASSESSING SPECIES DISTRIBUTIONS IN TERMS OF FOREST RESTORATION AND FIRE RISK IN THE SIERRA NEVADA
|Kristin M Brunk; Cornell Lab of Ornithology; email@example.com; Charles Maxwell, Gavin M. Jones, Zach Peery, LeRoy Westerling, Anu Kramer, Kevin Kelly, Joshua F. Goldberg, Connor M. Wood
A warming climate and rapid land-use change have altered disturbance regimes globally, and, in the dry forests of western North America, managers face increasingly critical and time-sensitive trade-offs when planning forest restoration activities. However, identifying and balancing potential trade-offs between forest restoration goals and biodiversity conservation is hindered by mismatches between existing wildlife ecology research and forestry metrics that can hamper managers’ ability to utilize existing information in decision-making. Here, we (1) determine the occupancy of ten avian indicator species across the entire Sierra Nevada ecosystem using passive acoustic monitoring at an unprecedented spatial scale and (2) directly link species’ distributions to forestry metrics and fire risk using a novel habitat dataset that is congruent with the metrics used by managers in forest restoration planning. We found that the ten species responded to habitat and fire risk idiosyncratically, which provides insight into the diversity of restoration and management strategies that will be necessary to protect the unique and varied forest communities of the Sierra Nevada. This work navigates the space between conservation research and regional planning and provides actionable information for managers seeking to understand species distributions relative to wildfire risk in the context of adaptive management and evidence-based conservation.
USING TECHNOLOGY TO REDUCE LEAD POISONING IN CALIFORNIA CONDORS
|Kara K Fadden; Ventana Wildlife Society; firstname.lastname@example.org; Mike Stake, Joe Burnett, Darren Gross, Evan McWreath, Danaé Mouton
Once extinct from the wild, the California Condor's (Gymnogyps californianus) global population has increased to over 500 individuals over the last 35 years through intensive management efforts of dedicated individuals and agencies. In spite of these efforts, lead poisoning continues to be the most challenging obstacle for condor recovery. Ventana Wildlife Society (VWS), which co-manages the Central California Condor population with Pinnacles National Park, started a free non-lead program in 2012 to mitigate lead exposure. Since then, VWS has provided over 13,000 boxes of non-lead ammunition to hunters and ranchers within the condor range. However, an ammunition shortage since 2020, required VWS to develop a more critical and efficient approach to prioritize distribution to individuals having the greatest potential impact on condor survival. Using high-resolution GPS data from transmitters placed on condors, biologists were able to use GIS to pinpoint probable condor feeding events, and identify potentially high risk properties. Though this method has helped focus outreach efforts, it has also emphasized the need for placement of GPS transmitters on more condors. This will provide a more complete analysis of condor scavenging patterns, a better assessment of outreach priorities, and greater progress toward eliminating lead from the environment.
USING AN INNOVATIVE DATA SHARING APPLICATION TO COORDINATE THE EFFORTS OF CALIFORNIA CONDOR RECOVERY PARTNERS
|Danae C Mouton; Ventana Wildlife Society; email@example.com; Tim Huntington, Darren Gross, Kara Fadden, Evan McWreath, Joe Burnett, Mike Stake
Once extinct in the wild, over 300 California Condors (Gymnogyps californianus) now make up five distinct and intensively managed subpopulations in California, Arizona, and Baja, Mexico. All five flocks are managed by multiple agencies, creating the need for standardization and collaboration among federal, non-profit, tribal, and international partners. To meet this need and increase efficiency in the management of this critically endangered species, Ventana Wildlife Society’s Senior Software Engineer Tim Huntington developed the CACO Central application. Field data related to movements, nesting, handling, and much more is uploaded to the application in real-time by biologists, and is consolidated in one location, allowing for easy access and more effective responses by field teams. By regularly compiling and pre-processing millions of condor GPS locations, CACO Central reduces this workload for biologists, enabling them to focus instead on using GPS data to inform management decisions. The standardization of data formatting across all flocks and monitoring agencies has also increased efficiency in broader-scale research projects involving condors. While some features of CACO Central are specific to condors, many of its core functions can and should be applied to a wide variety of species and monitoring projects in the ornithological field and beyond.