Ornithology I

Contributed Oral

 
Managing Wildlife Openings to Benefit Game and Non-Game Bird Species in Central Appalachian Forests
Hannah Clipp, Christopher Rota, Petra Wood
In forested landscapes of the Central Appalachians, wildlife openings are created and maintained by land managers to provide early-successional habitat (e.g., areas of herbaceous ground cover, shrub-scrub, or young forest) for three regionally-important game birds — wild turkey (Meleagris gallopavo), ruffed grouse (Bonasa umbellus), and American woodcock (Scolopax minor). These wildlife openings can also benefit a myriad of non-target (i.e., non-game) avian species and guilds, depending on local habitat features and landscape-level factors. Yet little effort has been made to investigate how to optimally manage wildlife openings to attract a full spectrum of avifauna throughout spring and summer and maximize richness across habitat guilds. Therefore, the purpose of this study is to examine the sympatric use of wildlife openings by game birds, breeding songbirds, and post-breeding songbirds in response to site- and landscape-level wildlife opening characteristics. Our objectives are to determine how local habitat attributes, opening size, management actions, and landscape context relate to (1) avian guild richness, (2) occupancy of specific game birds, breeding songbirds, and post-breeding songbirds, and (3) abundance of specific early-successional, edge-associated, and forest-interior breeding songbird species in wildlife openings. In April–August 2019–2021, we used species-specific and community-wide point count surveys, acoustic recording units, game cameras, and transect surveys to sample the avian communities of nearly 300 wildlife openings within the Monongahela National Forest in eastern West Virginia. Results from multi-species occupancy and n-mixture models indicate vegetative cover and opening size influence avian guild richness and occupancy/abundance of certain focal species. Ultimately, these results will assist in the design and management of wildlife openings that simultaneously support target game bird populations and promote a diverse suite of songbirds.
 
Identifying Drivers of Avian Demographics: Effects of Climate and Forest Structure on Songbird Survival and Breeding Seasonality in Northern California and Southern Oregon
Jared Wolfe, John Alexander, C. John Ralph, Pedro Martins, Jaime Stephens, Linda Long
Interactions between climate and forest structure moderate food and cover resources for songbirds. These resources, in turn, affect patterns of survival and reproductive success which influence species distribution across the landscape. In this study, we used 21 years of bird capture data from 64 locations across northern California and southern Oregon to measure the effects of climate and forest structure on the survival and the timing of breeding for 24 songbird species. Our study uncovered four general patterns of avian survival where study species survival varied by: (1) structural elements, (2) geography and elevation, (3) either an interaction or additive effect between climatic, structural, and/or geographic explanatory variables, or (4) nothing at all. Regarding breeding, warmer springs and summers resulted in earlier breeding seasons for 6 of the 24 study species. These findings suggest that survival responded to a dissimilar suite of environmental variables while breeding seasonality was broadly affected by climate. The diversity of demographic responses should be considered when identifying potential conservation actions to benefit songbird communities in North America and beyond.
 
Initial Evaluation of Avian Use of Agricultural Cover Crops during the Winter, Migration Stopover, and the Breeding Season in Tennessee
Brittany Panos, David Buehler, Craig Harper
The U.S. Department of Agriculture Natural Resources Conservation Service administers the winter cover crop program to provide financial incentives to agricultural producers to sow herbaceous plant seeds to protect agricultural fields from soil erosion during the non-growing season (late fall through spring). As of fall 2020, 58,643 hectares were certified as planted with cover crops through NRCS in Tennessee. Although benefits related to soil retention and water quality improvements have been documented, potential benefits to birds remain largely unknown. We are investigating use of cover crop fields by birds during the stationary non-breeding period, migration, and the breeding season by comparing bird use of cover crop fields with no-till row-crop fields without cover crops. We selected 77 fields with cover crops and 30 control fields without cover crops for evaluation in four counties across middle and western Tennessee. We monitored avian use along two 100-m line transects in each field in a distance-sampling framework every three to four weeks, January – June 2021. We also employed supplemental drive netting with mist nets and banding to further quantify avian use. We will nest-search during the breeding season for focal grassland species to document how these fields support breeding birds. During the winter 2021 season, we detected 46 species (96%) on cover crop fields and 24 species (50%) on control fields. We will present results from the full 2021 field season, describing avian use of no-till crop fields with and without cover crops, and how vegetation cover influenced use.
 
Wetland Dewatering and Predation Risk at Marsh Bird Nests
Stephanie M. Schmidt, Thomas J. Benson, Auriel Fournier, Joshua M. Osborn
Marsh birds are associated with complex vegetated habitat interspersed with open water that provides protection from terrestrial predators. They are also habituated to dynamic hydric conditions as would be seen in a floodplain wetland. Unfortunately, marsh birds are experiencing population declines that are believed to be driven by wetland loss and predation. Wetland loss is characteristic to the United States’ heavily altered landscape, and it is especially prevalent in Illinois where 90% of hydric soils were drained for agriculture. Proper management of remaining wetland habitat is a potential solution for mitigating further marsh bird losses. Emiquon Preserve, a restored cattail marsh separated from the Illinois River, is managed as a semi-emergent marsh through seasonal water drawdowns. It uses a pump to control drawdowns after marsh birds initiate nesting, and drawdowns follow annual cycles of intensity. In 2020 Emiquon Preserve underwent an intense 4.5 ft drawdown intended to expose moist soil for plants that feed migrating waterfowl. However, knowledge on how the timing and intensity of these drawdowns affect nesting marsh birds is limited, but there is concern that removal of water may increase predation risk and further exacerbate marsh bird losses. In 2020, we searched suitable habitats (hemi-marsh, dense emergent) and located marsh bird nests (least bittern, common gallinule, American coot, black-crowned night-heron) (n=88) at varying water depths. We set up continuously recording cameras at a subset of the nests (n=52) to record predators and we revisited all nests regularly to document fate. We found that least bittern and common gallinule nests in shallow water and closer to the water’s edge faced an increase in predation, and mammalian predation was greatest under these conditions. The results of this study highlight the importance of keeping water below and around marsh bird nests during wetland management to limit predator access to nests.
 
Evaluating Avian Occupancy on Sites Treated Using NRCS Conservation Practices Implemented to Benefit Cerulean and Golden-Winged Warblers in West Virginia
Kyle Aldinger, Lincoln Oliver, Christopher Lituma, Petra Wood, Richard Bailey
Through the Cerulean Warbler (Setophaga cerulea) Appalachian Forestland Enhancement Project (CWAFEP) and the Working Lands for Wildlife (WLFW) Golden-winged Warbler (Vermivora chrysoptera) initiative, the USDA – Natural Resources Conservation Service (NRCS) provides technical and financial assistance to private landowners to implement conservation practices that follow science-based habitat management guidelines to restore habitat. Few research studies have evaluated focal species-specific occupancy on CWAFEP and/or WLFW sites, and research is needed to inform each conservation project’s effectiveness in an adaptive management framework. Our objective was to evaluate the effectiveness of conservation practice implementation on Cerulean and Vermivora Warbler occupancy at CWAFEP and WLFW sites. During May – July in 2019 and 2020, we conducted point count surveys at 341 point count locations on 19 CWAFEP sites, 20 WLFW sites, and 2 sites enrolled in both projects in West Virginia. There were no differences in Cerulean and Vermivora Warbler occupancy estimates at untreated and treated locations. Our study suggests that Cerulean and Vermivora Warbler occupancy was not positively affected by recent conservation practice implementation (1 – 8 years post-treatment) and that both CWAFEP and WLFW projects need to adhere more strictly to published habitat management guidelines to be effective for conservation. The lack of differences in occupancy was likely due to private lands variability, site selection, small treatment areas, and challenges associated with private lands conservation resulting in insufficient basal area removal. Post-treatment basal area was above the published recommended range at 40% of CWAFEP locations and 86% of WLFW locations. Achievement of the published basal area range during contract implementation and refinement of both project’s focal areas in West Virginia is needed to improve each project’s effectiveness. Our findings can help NRCS adapt and improve conservation efforts for Cerulean and Golden-winged Warblers on private lands.
 
Abundant Natural Cavities in a Deciduous Forest Leads to a Lack of Nest Box Occupancy for Northern Saw-Whet Owls
Joseph Elias, Scott Stoleson
Nest boxes are a commonly-used tool to manage and study species that utilize tree cavities. A nest box system developed in 2011 for Northern Saw-whet Owls in northern Pennsylvania was checked after a hiatus of eight years; but we found no evidence of any owl usage over that time. We used standardized playback surveys to determine that owls were indeed present at eight of eleven boxes checked. Surveys of tree cavities revealed an average of 7.7 cavities of a size appropriate for use by saw-whet owls within 50 m of each box; extrapolation of cavity densities to a minimal owl territory size of 150 ha suggested that suitable cavities are an abundant and non-limiting resource here. Cavity abundance was likely due in part to the consequences of beech bark disease complex having recently top-killed most large American Beech trees locally, providing abundant resources for excavating woodpeckers. We suggest that assessing cavity abundance in a system is an essential first step for any management project involving cavity-nesting birds, and that nest boxes be constructed and used only in situations where cavities appear to be limited.
 
Louisiana Waterthrush and Worm-Eating Warblers with Opposing Breeding Population Trends Are Spatially Segregated during the Non-Breeding Season
Silas Fischer, Gunnar Kramer, Eliot Berz, Patrick Ruhl, David Aborn, Rick Huffines, Henry Streby
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 contrasting long-term population trends. 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.
 
Initial Evaluation of Avian Use of Agricultural Cover Crops during the Winter, Migration Stopover, and the Breeding Season in Tennessee
Brittany Panos
The U.S. Department of Agriculture Natural Resources Conservation Service administers the winter cover crop program to provide financial incentives to agricultural producers to sow herbaceous plant seeds to protect agricultural fields from soil erosion during the non-growing season (late fall through spring). As of fall 2020, 58,643 hectares were certified as planted with cover crops through NRCS in Tennessee. Although benefits related to soil retention and water quality improvements have been documented, potential benefits to birds remain largely unknown. We are investigating use of cover crop fields by birds during the stationary non-breeding period, migration, and the breeding season by comparing bird use of cover crop fields with no-till row-crop fields without cover crops. We selected 77 fields with cover crops and 30 control fields without cover crops for evaluation in four counties across middle and western Tennessee. We monitored avian use along two 100-m line transects in each field in a distance-sampling framework every three to four weeks, January – June 2021. We also employed supplemental drive netting with mist nets and banding to further quantify avian use. We will nest-search during the breeding season for focal grassland species to document how these fields support breeding birds. During the winter 2021 season, we detected 46 species (96%) on cover crop fields and 24 species (50%) on control fields. We will present results from the full 2021 field season, describing avian use of no-till crop fields with and without cover crops, and how vegetation cover influenced use.
 
The Influence of Pine Management on Grassland-Nesting Birds Overwintering in Central Louisiana
Nancy Raginski, Ashley Long
In the southeastern U.S. pine forests cover ~28 million ha and are most often used for commercial timber and hunting. Management practices used to reach desired vegetative conditions in these forests (e.g., prescribed fire) may simultaneously influence distributions of overwintering songbirds, including several species of conservation concern that breed in grasslands of the northern U.S. and throughout Canada. From December to February of 2018–2020, we surveyed 26 study sites in longleaf (Pinus palustris) and loblolly pine (P. taeda) stands to examine the influence of pine management on grassland-nesting birds overwintering in central Louisiana. We used single-season occupancy and N-mixture models to model occupancy and density of grassland-nesting species of conservation concern that we detected during our surveys. We also used analysis of variance to compare characteristics of vegetation used by grassland-nesting species of conservation concern in longleaf stands burned 0–2 years ago. We recorded 9,014 detections of 64 species including six grassland-nesting species. Henslow’s sparrow (Centronyx henslowii) occupancy increased with increasing vegetation height, Bachman’s sparrow (Peucaea aestivalis) occupancy was greatest in longleaf stands, and sedge wren (Cistothorus platensis) occupancy increased with decreasing percent canopy cover. We also found that Henslow’s sparrow density decreased with increasing litter depth, Bachman’s sparrow density increased with increasing herbaceous density between 0–0.1m in both stand types, and sedge wren density increased with increasing percent herbaceous cover. Finally, we found significant differences in vegetation metrics used by all three species in longleaf stands burned 0–2 years ago. Our results indicate that fire return intervals of 0–2 years creates vegetation structure that can support multiple species of grassland-nesting birds overwintering in Louisiana. Our research will help inform more comprehensive management of grassland-nesting birds overwintering in pine forests of the southeastern U.S.
 
A Call for Fully Accounting for Effects of Nest Age When Quantifying Nest Survival
Emily Weiser
Accurately measuring nest survival is challenging because nests must be discovered to be monitored, but nests are typically not found on the first day of the nesting interval. Samples in nest survival therefore often overrepresent older nests. To account for this, a daily survival rate (DSR) is estimated and used to calculate nest survival to the end of the interval. However, estimates of DSR (and thus nest survival) can still be biased if DSR changes with nest age and nests are not found at age 0. Including nest age as a covariate of DSR and carefully considering the method of estimating nest survival can prevent such biases, but many published studies have not fully accounted for changes in DSR with nest age. I used a simulation study to quantify biases in nest survival estimates resulting from effects of nest age on DSR under a variety of scenarios. I tested four methods of estimating nest survival from the simulated datasets and evaluated the bias and variance of each estimate. Nest survival estimates were often strongly biased when DSR varied with age but the model assumed DSR was constant. Biases were also often strong when the model included age as a covariate but calculated nest survival from DSR at the mean monitored nest age, which is the method typically used in previous studies. In contrast, biases were usually avoided when nest survival was calculated as the product of age-specific estimates of DSR across the full nesting interval. Future field studies can maximize accuracy and precision of nest survival estimates by aiming to find nests at young ages, including age as a covariate in the DSR model, and calculating nest survival as the product of age-specific estimates of DSR when DSR changes with nest age.

Contributed Oral
Location: Virtual Date: November 2, 2021 Time: 4:00 pm - 5:00 pm