Songbird Conservation & Management

Contributed Oral Presentations

SESSION NUMBER: 68

Contributed paper sessions will be available on-demand for the duration of the conference, then again at the conclusion of the conference.

 

Post-Fledging Survival, Habitat Associations, and Movements of Gray Vireos in New Mexico
Silas E. Fischer; Kathy Granillo; Henry M. Streby
Most studies of reproductive success and habitat associations of songbirds include only the nesting stage. But information from the post-fledging period, or the stage after young (hereafter, fledglings) leave the nest and prior to migration, can improve our understanding of demography and habitat requirements. Songbird annual population growth (ƛ) may be particularly sensitive to variation in fledgling survival, and fledglings of some species use areas with different habitat characteristics than those used for nesting. We used radio telemetry to study post-fledging survival, habitat associations, and movements of Gray Vireos (Vireo vicinor), a migratory songbird of conservation concern for which few annual cycle data are available. At Sevilleta National Wildlife Refuge (New Mexico) during 2017-2020, we tracked 90 Gray Vireo fledglings and found that 51% survived the monitoring period. We observed the highest mortality during the first few days post-fledging, consistent with other songbird studies. Focusing on predation-related mortalities to assess survival in relation to habitat, daily survival of fledglings was best predicted by and positively associated with age. During the first 12 days post-fledging at the 25-m-radius scale, fledglings used areas higher tree density (15 ± 9%) compared to random points (mean 9 ± 9%), but similar to nesting areas (15 ± 10%). Fledglings used oneseed juniper (Juniperus monosperma) trees during 88% of observations. Minimum daily distance traveled, distance from the nest, and associated variation increased with age, with some fledglings attended to by female parents traveling >2km from nests. Preliminary population models suggest that nest productivity and fledgling survival are sufficient for our study population to be numerically stable. Unless there is a post-fledging habitat component preferred by Gray Vireos and missing from our study area, results indicate that conserving large areas of nesting habitat may be sufficient for providing full breeding season habitat for this species.
Breeding Ecology of Blue-Winged Warblers in Managed Shrublands in Southwest Pennsylvania
Kristin Bomboy; Jeffery L. Larkin; Joseph Duchamp; Michael Tyree; Carol I. Bocetti
The Blue-winged Warbler (Vermivora cyanoptera) is a shrubland songbird experiencing annual population declines in Pennsylvania, and loss of early successional breeding habitat is thought to be contributing to their decline. Several studies have provided insight about breeding habitat characteristics for the closely related and more imperiled Golden-winged Warbler (Vermivora chrysoptera), however, few studies have examined breeding habitat characteristics of Blue-winged Warblers, and none have used radio telemetry to do so. We studied the breeding ecology of Blue-winged Warblers occupying managed shrublands in southwest Pennsylvania. We captured and attached radio-transmitters to adult males in early May and monitored their movements throughout the breeding season, then sampled vegetation within each male’s home range (95% KDE) and core territory (50% KDE). On average, Blue-winged Warbler home ranges (11.8 ± 5.3 ha) were 4.5 times larger than core territories (2.6 ± 1.3 ha). Core territories were primarily comprised of shrublands and early-successional forest, while home ranges were comprised of a mix of shrublands and early-, mid- and late-successional forest. Home ranges had less grass and goldenrod (Solidago spp.) cover than core territories. Furthermore, an average of 20.7% of observed locations fell within forested areas and average distance to an open area was 36 m. These results suggest that Blue-winged Warblers use a greater diversity of cover types during the breeding season than previously described. Similar to Golden-winged Warbler breeding habitat recommendations, managers should create a mosaic of shrublands and multi-aged forest to meet the breeding season needs of Blue-winged Warblers.
Monitoring Avian Response to Nrcs Conservation Practices Implemented to Benefit Cerulean and Golden-Winged Warblers in West Virginia
Lincoln Oliver; Richard Bailey; Kyle R. Aldinger; Christopher M. Lituma; Petra B. Wood
Cerulean Warbler (Setophaga cerulea) and Golden-winged Warbler (Vermivora chrysoptera) are two high-priority species for conservation. As such, species-specific habitat management has been prioritized for each species to create breeding habitat. Both Cerulean and Golden-winged Warbler are focal species for Natural Resources Conservation Service (NRCS) conservation projects that target the creation of breeding habitat on private lands in priority areas of the Appalachians. An extensive body of literature is used to inform on-the-ground management implemented in each project. However, there is a need to quantify each species response to management on private lands, which are often smaller and more variable than treatment areas used in previous research. Additionally, little research has investigated the impacts to the overall avian community in response to species-specific management implemented for each species on private lands. Our goal is to examine Cerulean Warbler, Golden-winged Warbler, woodland, and shrubland focal species occupancy and abundance as well as avian species richness in response to species-specific management on private lands. Our objectives are to determine how species-specific management actions and vegetation, site-level, and landscape attributes affect (1) Cerulean and Golden-winged Warbler occupancy and abundance, (2) avian species richness, and (3) occupancy and abundance of associated avian focal species. From May-June, 2019-2020, we used point count surveys to sample avian communities at private properties enrolled in NRCS conservation projects throughout West Virginia. We concurrently collected structural site-specific vegetation information. We prioritized properties with pre-treatment NRCS conservation practices in 2019 to establish baseline information and post-treatment in 2020 to evaluate-post-treatment response. With data collection and statistical analyses completed, results will inform land managers in creating suitable breeding habitat for each species and provide a measure of private-land management’s effectiveness in providing breeding habitat for Cerulean and Golden-winged Warbler, as well as the overall avian community.
Variation in Space Use and Exposure to Potential Risk Factors during Migration Are Not Associated with Vermivora Warbler Population Trends
Gunnar R. Kramer; David E. Andersen; David A. Buehler; Petra B. Wood; Sean M. Peterson; Justin A. Lehman; Kyle R. Aldinger; Lesley P. Bulluck; Sergio Harding; John A. Jones; John P. Loegering; Curtis Smalling; Rachel Vallender; Henry Streby
Golden-winged Warblers (Vermivora chyrsoptera) and Blue-winged Warblers (V. cyanoptera) are Neotropical-Nearctic migrants experiencing varied regional population trends that have recently been linked to strong migratory connectivity and historical forest loss at population-specific nonbreeding areas. Preliminary evidence also suggests populations of Vermivora warblers may exhibit variation in space use during migration potentially leading to differential exposure to factors that influence mortality risk. Whether these factors experienced during migration are driving population trends of Vermivora warblers is unknown. We used geolocator data from 90 individual Vermivora warblers tracked during 2013-2017 to investigate whether variation in exposure to a suite of anthropogenic and natural risk factors was associated with recent breeding population trends. Overall, Vermivora warblers exhibited population-specific space use during migration and these differences were associated with variation in exposure to anthropogenic and natural risk factors. However, none of these risk factors helped explain additional variation in population trends after accounting for migratory connectivity (i.e., breeding and nonbreeding region). Our results suggest that factors experienced during migration are unlikely to be driving regional variation in recent Vermivora warbler population trends. We did find, however, that regional differences in projected changes in land use may differentially affect populations of Vermivora warblers during migration in the future. Maintaining suitable stopover habitat is critical for the successful conservation of migratory species, but our results suggest that factors experienced along migration routes are not currently limiting populations of Vermivora warblers.
Insights into Detection and Habitat Use of Black- and Yellow-Billed Cuckoos, Two Declining and Poorly Understood Species
Claire Johnson; Thomas J. Benson
Black-billed Cuckoos (Coccyzus erythropthalmus) and Yellow-billed Cuckoos (Coccyzus americanus) have experienced extensive range-wide population declines over the last several decades. However, as cuckoos are patchily distributed and hard to detect, population size and trend estimates are not well supported and habitat requirements are poorly understood. We set out to examine habitat use and detection probability for both species. We performed passive and call-broadcast surveys for cuckoos at 41 sites in northeastern Illinois and used radio telemetry to track Black-billed Cuckoos at a subset of sites. We examined the influence of habitat covariates on occupancy and the effect of call-broadcast and temporal and environmental covariates on detection probability. Each species was detected at > 50% of sites, and while sites were more likely to have both species than expected by chance, each appeared to use different areas within these sites. However, vegetation structure and composition did not consistently predict habitat use within and among sites for either species. Detection probability was increased substantially (up to 2.6 and 11 times for Yellow-billed and Black-billed Cuckoos, respectively) by using call-broadcasts, but varied throughout the breeding season and between species. Black-billed Cuckoos ranged widely within sites, and home range size varied among individuals. Our results suggest call-broadcasts are essential for understanding distribution and population trends. Unfortunately, the fact that broadcast surveys attracted cuckoos to a survey point, coupled with low detection probability and potentially large home ranges, may have obscured relationships between habitat covariates and use. Site-level variables and characteristics at actual use points may be more important for determining selection within and among sites. Improving our understanding of detection and habitat selection is an important step towards effective management for these two declining species.
Louisiana Waterthrush and Worm-Eating Warblers with Opposing Breeding Population Trends Are Spatially Segregated during the Non-Breeding Season
Henry M. Streby; Silas Fischer; Eliot Berz; Gunnar Kramer; David Aborn; Patrick Ruhl; Rick Huffines
Migratory birds can experience bottlenecks, or factors limiting population growth, during any stage of their annual cycle. It is especially important to study migratory connectivity and non-breeding dispersion for populations of songbirds for which breeding-grounds factors have little apparent relationship to local and regional population trends. Louisiana Waterthrush (Parkesia motacilla) and Worm-eating Warblers (Helmitheros vermivorum) are ground-nesting wood warblers (Parulidae) with largely overlapping breeding distributions in eastern North America and with similarly stable or slightly positive global population trends in recent decades. These two species breed in mature forest, often with territories on hillsides associated with streams and other small waterways. Despite similarities in global population trends and breeding habitat associations, these species exhibit opposing population trends (i.e., one species is increasing while the other is decreasing) at local and regional scales across their breeding distribution. Whether these trends are associated with minor breeding-grounds factors, or factors experienced during other portions of the annual cycle, is currently unknown. We used light-level geolocators to infer migration routes and wintering locations for 21 Louisiana Waterthrush and 18 Worm-eating Warblers from breeding sites in Arkansas, Tennessee, Ohio, and Pennsylvania, USA. At each site, these species exhibited long-term population trends in opposite directions. We identified considerable non-breeding segregation between species at each breeding site suggesting that factors occurring during the non-breeding period could be associated with the incongruent breeding population trends. Further investigation of factors experienced by each population during the non-breeding period is underway.
Bird Banding Records Demonstrate That Some Northern Cardinals Disperse Long Distances
Daniel Shustack
Dispersal is an important ecological process that has implications for range expansion, gene flow and metapopulation dynamics. While there are a variety of methods for studying avian dispersal, banding and subsequent encounters of those marked birds provide information on dispersal rates and distances. I reviewed the BBL encounter records of the Northern Cardinal (Cardinalis cardinalis) in order to describe their dispersal patterns. Of the 11,640 encounters of banded Cardinals in the database, 2887 were appropriate for analysis because they represent random recoveries of dead cardinals as opposed to encounters from targeted research activities. Most cardinals remain within the 10-minute banding block in which they were banded, however, 21.9% were encountered at least one block away. The precision of banding and encounter locations limit fine-scale examination of dispersal distance, but young cardinals were slightly more likely to display natal dispersal (0.27 moved from their natal banding block) than adults were to display breeding dispersal (0.21 moved from their banding block). Most cardinals do not disperse very far; 95.4% of all cardinals were encountered within 25 km of their banding location. Natal dispersal distances averaged slightly larger than breeding dispersal distances. Only 2% of encounters were from cardinals encountered more than 100 km from the banding location. The longest cardinal movement in the BBL records is an individual (unknown sex and age) which moved 1800 km northward over 23 months. These long-distance movements appear to be exceptional and cardinals display a strong tendency to remain near their banding locations throughout their lives.
Predation Threat in a Variable Landscape: Connecting Predation Risk to Nesting Success for the Seaside Sparrow
Corina Diana Newsome; Elizabeth Hunter
Birds inhabiting Atlantic coastal marshes are experiencing significant and rapid changes to their habitat, specifically in the form of sea level rise and encroaching urbanization. In seaside sparrows (Ammospiza maritima; SESP), sea level rise presents an inherent threat to nest success in its potential to cause nest flooding. In addition to this direct threat, the ability for SESP to adaptively respond to sea level rise can be constrained by predation pressure. As SESP elevate their nests to avoid flooding, their nests become more vulnerable to predation. This research aims to understand the predictability of SESP nest predation threat in Georgia’s saltmarshes along two major gradients: distance to roads and distance to main rivers (rivers ≥150ft in width). First, using two focal sites in coastal Georgia, USA, we assessed mammalian predator occurrence along the two gradients of interest; we hypothesized that predator occurrence would increase with increasing closeness to roads and closeness to main rivers. Second, we recorded the occurrence of SESP nest predation events in the areas assessed for predator occurrence; we hypothesized that nest predation events would increase with increasing probability of predator occurrence. The pattern of mammalian predator occurrence supported our hypotheses along both gradients; however, SESP nest predation did not track mammalian predator distribution. Understanding the predictability of nest predation threat across SESP breeding habitat equips us with valuable information that could be used to address this major constraint to their ability to survive as sea level rise intensifies.
Fowl Language: Cassin’s Sparrow Males Use Different Songs in Different Contexts
Dylan Joesph Allenback
Cassin’s Sparrows (Peucaea cassinii), although not the prettiest to look at, may be one of the most interesting of songbirds in prairies of North America. Cassin’s Sparrows are understudied and are declining by 3% per year in Colorado. Cassin’s Sparrow males, like many other birds, have displays and songs that they use to defend territories and attract mates, but unlike many songbirds, Cassin’s Sparrows have two very distinct songs. Anecdotal evidence suggests that these songs may be used in different social contexts and may have different functions. We used playback experiments to try to determine the function of these two songs and in what context male Cassin’s Sparrow are using them. The data suggest that one song may be used for initial attraction of a mate and the other may be used to defend that mate from neighboring males. Males that are accompanied by females in their territories tend to use one song more than males without a female present in their territories. Further analyses will include comparison of song use at different stages of nesting. This research will increase understanding of the basic breeding behavior of this bird and may assist in future conservation efforts for this species.
Long-Distance Natal Dispersal as a Resource Tracking Mechanism in Black-Backed Woodpeckers
Andrew Stillman; Teresa Lorenz; Philip Fischer; Rodney Siegel; Robert Wilkerson; Matthew Johnson; Morgan Tingley
Black-backed woodpeckers (Picoides arcticus) are strongly associated with recently burned forests in western North America where they specialize on resources present in dead and dying trees. However, the ephemeral and unpredictable occurrence of burned forests poses an intriguing puzzle for specialized species: how do individuals track the location of these resource patches and colonize newly burned forests? We used a combination of ground-based and aerial telemetry to track the natal dispersal movements of black-backed woodpeckers originating in burned forests of California and Washington. We built a bias-corrected dispersal kernel for the species and designed a novel Bayesian model to examine the factors that influence dispersal probability while accounting for imperfect detection. The bias-corrected median dispersal distance was 18.4 km with a maximum recorded distance of 51 km. Juveniles from older burned forests, where resources are increasingly scarce, dispersed longer distances and were more likely to leave their natal fire compared to juveniles from newer burns. Simulation analyses demonstrated that black-backed woodpeckers select for burned forests relative to available habitat while dispersing across the landscape. Our results provide strong support for the hypothesis that black-backed woodpeckers track resource pulses across fire-prone landscapes, with long-distance natal dispersal acting as a mechanism for rapid post-fire colonization of newly burned areas. These findings also highlight the management importance of wildland fires, and the resource-dense snag patches they create, to the persistence of this species in coniferous forests of the Western U.S.

 

Virtual
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