Food availability aligns with contrasting demographics in populations of an at-risk songbird.

Golden-winged Warblers (Vermivora chrysoptera) have become rare across much of their historic breeding range and response to conservation efforts is variable. Evidence from several recent studies suggests that breeding output is a primary driver explaining responses to conservation and it is hypothesized that differences in food availability may be driving breeding output disparity between two subpopulations of the warbler's Appalachian breeding range. Herein, we studied two subpopulations: central Pennsylvania ("central subpopulation"), where breeding productivity is relatively low, and eastern Pennsylvania ("eastern subpopulation"), where breeding productivity is relatively high. To test the food-availability hypothesis in this system, we measured density of caterpillars, plasma lipid metabolites (triglycerides [TRIG; fat deposition] and glycerol [GLYC; fat breakdown]), body mass of adults males, and acquired body mass data for fledglings at 38 sites managed for nesting habitat. Consistent with our prediction, leaf-roller caterpillar density, the group upon which Golden-winged Warblers specialize, was 45× lower in the central subpopulation than the eastern subpopulation. TRIG concentrations were highest within the eastern subpopulation during breeding grounds arrival. The change in TRIG concentrations from the breeding-grounds-arrival stage to the nestling-rearing stage was subpopulation dependent: TRIG decreased in the eastern subpopulation and was constant in the central subpopulation, resulting in similar concentrations during the nestling-rearing stage. Furthermore, GLYC concentrations were higher in the eastern subpopulation, which suggests greater energy demands in this region. Despite this, adult male warblers in the eastern subpopulation maintained a higher average body mass. Finally, fledgling body mass was 16% greater in the eastern subpopulation than the central subpopulation before and after fledging. Collectively, our results suggest that poor breeding success of Golden-winged Warblers in the central subpopulation could be driven by lower availability of primary prey during the breeding season (leaf-roller caterpillars), and this, in turn, limits their response to conservation efforts.

A large-scale assessment of eastern whip-poor-will (Antrostomus vociferus) occupancy across a gradient of forest management intensity using autonomous recording units.

Conservationists spend considerable resources to create and enhance wildlife habitat. Monitoring how species respond to these efforts helps managers allocate limited resources. However, monitoring efforts often encounter logistical challenges that are exacerbated as geographic extent increases. We used autonomous recording units (ARUs) and automated acoustic classification to mitigate the challenges of assessing Eastern Whip-poor-will (Antrostomus vociferus) response to forest management across the eastern USA. We deployed 1263 ARUs in forests with varying degrees of management intensity. Recordings were processed using an automated classifier and the resulting detection data were used to assess occupancy. Whip-poor-wills were detected at 401 survey locations. Across our study region, whip-poor-will occupancy decreased with latitude and elevation. At the landscape scale, occupancy decreased with the amount of impervious cover, increased with herbaceous cover and oak and evergreen forests, and exhibited a quadratic relationship with the amount of shrub-scrub cover. At the site-level, occupancy was negatively associated with basal area and brambles (Rubus spp.) and exhibited a quadratic relationship with woody stem density. Implementation of practices that create and sustain a mosaic of forest age classes and a diverse range of canopy closure within oak (Quercus spp.) dominated landscapes will have the highest probability of hosting whip-poor-wills. The use of ARUs and a machine learning classifier helped overcome challenges associated with monitoring a nocturnal species with a short survey window across a large spatial extent. Future monitoring efforts that combine ARU-based protocols and mappable fine-resolution structural vegetation data would likely further advance our understanding of whip-poor-will response to forest management.

Individual identification in acoustic recordings.

Recent advances in bioacoustics combined with acoustic individual identification (AIID) could open frontiers for ecological and evolutionary research because traditional methods of identifying individuals are invasive, expensive, labor-intensive, and potentially biased. Despite overwhelming evidence that most taxa have individual acoustic signatures, the application of AIID remains challenging and uncommon. Furthermore, the methods most commonly used for AIID are not compatible with many potential AIID applications. Deep learning in adjacent disciplines suggests opportunities to advance AIID, but such progress is limited by training data. We suggest that broadscale implementation of AIID is achievable, but researchers should prioritize methods that maximize the potential applications of AIID, and develop case studies with easy taxa at smaller spatiotemporal scales before progressing to more difficult scenarios.

Heterogeneity in breeding productivity is driven largely by factors affecting nestlings and young fledglings in an imperiled migratory passerine.

Identifying factors that drive variation in vital rates among populations is a prerequisite to understanding a species' population biology and, ultimately, to developing effective conservation strategies. This is especially true for imperiled species like the golden-winged warbler (Vermivora chrysoptera) that exhibit strong spatial heterogeneity in demography and responds variably to conservation interventions. Habitat management actions recommended for breeding grounds conservation include timber harvest, shrub shearing, and prescribed fire that maintain or create early successional woody communities. Herein, we assessed variation in the survival of nests [n = 145] and fledglings [n = 134] at 17 regenerating timber harvest sites within two isolated populations in Pennsylvania that differed in productivity and response to habitat management. Although the overall survival of nests and fledglings was higher in the eastern population than the central population, this was only true when the nest phases and fledgling phases were considered wholly. Indeed, survival rates of nestlings and recently fledged young (1-5 days post-fledging) were lower in the central population, whereas eggs and older fledglings (6-30 days post-fledging) survived at comparable rates in both populations. Fledglings in the central population were smaller (10% lower weight) and begged twice as much as those in the eastern population, suggesting food limitation may contribute to lower survival rates. Fledgling survival in the central population, but not the eastern, also was a function of habitat features (understory vegetation density [positive] and distance to mature forest [negative]) and individual factors (begging effort [negative]). Our findings illustrate how identifying how survival varies across specific life stages can elucidate potential underlying demographic drivers, such as food resources in this case. In this way, our work underscores the importance of studying and decomposing stage-specific demography in species of conservation concern.

Factors driving bumble bee (Hymenoptera: Apidae: Bombus) and butterfly (Lepidoptera: Rhopalocera) use of sheared shrubland and young forest communities of the western Great Lakes.

In the northern Great Lakes region, the creation and maintenance of early-successional woody communities as wildlife habitat have increasingly become a conservation priority. The extent to which insect pollinators use these systems remains largely anecdotal. In summer (June-August) of 2021, we surveyed 49 early-successional sites in the western Great Lakes region treated with either shrub-shearing or silviculture (young forest) for bumble bees, butterflies, and habitat components (i.e., structural vegetation and floral resources). Hierarchical distance models predicted pollinator densities (λ^) to be, on average, λ^ = 84 bumble bees/ha and λ^ = 102 butterflies/ha. Although sheared shrubland and young forest communities supported comparable densities of bumble bees and butterflies, density was not equal across all sites. At the microhabitat scale, butterfly density and morphospecies richness were negatively associated with tall shrub cover and butterfly morphospecies richness (but not density) was driven by floral richness. Similarly, bumble bee density was positively associated with metrics of floral resources, underscoring the importance of blooming plants within these woody systems. Landscape covariates explained variation in butterfly density/richness but not bumble bee density. Ultimately, our results demonstrate that blooming plant abundance is an important driver of bumble bee and butterfly densities within these managed early-successional communities. Because early-successional woody communities are dynamic and their herbaceous openings are ephemeral, routine management would ensure that a variety of successional conditions exist on the landscape to meet the needs of bumble bees, butterflies, and potentially other insect pollinators.

Parental benefits and offspring costs reflect parent-offspring conflict over the age of fledging among songbirds.

Parent-offspring conflict has explained a variety of ecological phenomena across animal taxa, but its role in mediating when songbirds fledge remains controversial. Specifically, ecologists have long debated the influence of songbird parents on the age of fledging: Do parents manipulate offspring into fledging to optimize their own fitness or do offspring choose when to leave? To provide greater insight into parent-offspring conflict over fledging age in songbirds, we compared nesting and postfledging survival rates across 18 species from eight studies in the continental United States. For 12 species (67%), we found that fledging transitions offspring from comparatively safe nesting environments to more dangerous postfledging ones, resulting in a postfledging bottleneck. This raises an important question: as past research shows that offspring would benefit-improve postfledging survival-by staying in the nest longer: Why then do they fledge so early? Our findings suggest that parents manipulate offspring into fledging early for their own benefit, but at the cost of survival for each individual offspring, reflecting parent-offspring conflict. Early fledging incurred, on average, a 13.6% postfledging survival cost for each individual offspring, but parents benefitted through a 14.0% increase in the likelihood of raising at least one offspring to independence. These parental benefits were uneven across species-driven by an interaction between nest mortality risk and brood size-and predicted the age of fledging among species. Collectively, our results suggest that parent-offspring conflict and associated parental benefits explain variation in fledging age among songbird species and why postfledging bottlenecks occur.

Implications for evolutionary trends from the pairing frequencies among golden-winged and blue-winged warblers and their hybrids.

Extensive range loss for the Golden-winged Warbler (Vermivora chrysoptera) has occurred in areas of intrusion by the Blue-winged Warbler (V. cyanoptera) potentially related to their close genetic relationship. We compiled data on social pairing from nine studies for 2,679 resident Vermivora to assess evolutionary divergence. Hybridization between pure phenotypes occurred with 1.2% of resident males for sympatric populations. Pairing success rates for Golden-winged Warblers was 83% and for Blue-winged Warblers was 77%. Pairing success for the hybrid Brewster's Warbler was significantly lower from both species at 54%, showing sexual selection against hybrids. Backcross frequencies for Golden-winged Warblers at 4.9% were significantly higher than for Blue-winged Warblers at 1.7%. More frequent backcrossing by Golden-winged Warblers, which produces hybrid phenotypes, may contribute to the replacement of Golden-winged by Blue-winged Warblers. Reproductive isolation due to behavioral isolation plus sexual selection against hybrids was 0.960. Our analyses suggest that plumage differences are the main driving force for this strong isolation with reduced hybrid fitness contributing to a lesser degree. The major impact of plumage differences to reproductive isolation is compatible with genomic analyses (Current Biology, 2016, 26, 2313), which showed the largest genetic difference between these phenotypes occurred with plumage genes. These phenotypes have maintained morphological, behavioral, and ecological differences during two centuries of hybridization. Our estimate of reproductive isolation supports recognition of these phenotypes as two species. The decline and extirpation of the Golden-winged Warbler in almost all areas of recent sympatry suggest that continued coexistence of both species will require eco-geographic isolation.

Higher Prevalence of Babesia microti than Borrelia burgdorferi in Small Mammal Species in Central Pennsylvania, United States.

Babesia microti can lead to severe babesiosis in immunosuppressed populations, but due to high numbers of asymptomatic cases, clinical reporting is unable to define its geographic distribution. Although Lyme disease caused by Borrelia burgdorferi is endemic throughout Pennsylvania (PA), human babesiosis is under recognized, despite sharing the same vector and primary reservoir host. Ixodes ticks are known to carry B. microti throughout PA, but information about pathogen prevalence in small mammal reservoirs remains limited. Characterizing B. microti prevalence in these small mammals can elucidate mechanisms of pathogen spread and define geographic areas where humans are at risk of infection. We tested 692 small mammals across eight contiguous counties in central PA for molecular evidence of B. microti and B. burgdorferi. In total, six different small mammal species were collected. The overall prevalence of B. microti was 32% with similar rates observed across all counties. Surprisingly, this was higher than the prevalence of B. burgdorferi at 21%. In fact, high rates of B. microti were found in all six species, and both pathogens were identified in 11% of mammals tested. The prevalence of B. microti was highest in Myodes gapperi (southern red-backed vole) at 39% despite Peromyscus leucopus (white-footed mouse) being considered the primary reservoir host for B. microti. In conclusion, B. microti has a high prevalence across multiple small mammal species throughout central PA. This prevalence is greater than B. burgdorferi despite a much higher incidence of Lyme disease compared to babesiosis in PA. Although it remains unknown how the prevalence of B. microti in small mammal hosts corresponds to human infection rates, the high pathogen prevalence of B. microti suggests that it is an emerging pathogen in this area. Currently, babesiosis is not a reportable disease in PA, and additional studies are warranted to evaluate its clinical significance in this geographic region.

Young Forest Conservation Incentive Programs: Explaining Re-Enrollment and Post-program Persistence.

Environmental conservation actions conducted by private landowners are critically important for conservation efforts worldwide. Incentive programs are used to engage landowners in voluntary conservation, but outcomes after landowners exit these programs are poorly understood. Previous research identified several pathways, including landowner motivations, cognitions, and resources, which could sustain or undermine continued conservation management behavior after incentive program participation. We tested the utility of these pathways for explaining management intentions of participants in U.S. Department of Agriculture, Natural Resources Conservation Service (NRCS) young forest habitat conservation programs in the eastern United States. We conducted a telephone survey of enrolled landowners in the programs from January to May 2017 (n = 102). We compared candidate multiple regression models to determine variables explaining landowner intentions to re-enroll in young forest programs or to persist with management without further cost-share. We found intentions to re-enroll in NRCS young forest programs were highest among landowners with high agency trust, and for whom cost-share, environmental concerns, and hunting were important motivations. Management persistence intentions were highest for group landowners (e.g., hunting clubs and nonprofits), landowners motivated by environmental concerns, and those less motivated by cost-share. Our results suggest that fostering trust through positive program experiences and recruiting landowners with supportive motivations and resources may encourage sustained young forest management. Differences in variables explaining program re-enrollment and management persistence in this study highlight the importance of considering these outcomes separately for conservation programs widely.

Effects of biological monitoring and results outreach on private landowner conservation management.

Sustained management efforts by private landowners are crucial for the long-term success of private land natural resource conservation and related environmental benefits. Landowner outreach is a primary means of recruiting private landowners into voluntary conservation incentive programs, and could also help sustain conservation behaviors through time. However, evaluation of outreach targeting landowners during or after participation in natural resource conservation incentive programs is lacking. We assessed two methods of landowner outreach associated with a Natural Resources Conservation Service incentive program targeting effective management of early successional forest habitat on private land in the Appalachians and Upper Great Lakes regions of the United States. While early successional forest habitat benefits many wildlife species, the program target species were the Golden-winged Warbler (Vermivora chrysoptera) and American Woodcock (Scolopax minor). After habitat management through the program occurred, biological technicians monitored wildlife and vegetation on enrolled properties and results were communicated to landowners in mailed packets. Our research focused on whether landowner interactions with technicians or receipt of result mailings could influence landowner post-program management intentions and management-related cognitions (e.g., agency trust, perceptions of outcomes). We conducted a telephone survey with landowners from January to May 2017, and analyzed survey data using quantitative group comparisons and qualitative coding methods. Landowners that accompanied biological technicians on monitoring site visits had higher agency trust and more positive perceptions of program outcomes. Result mailings did not improve landowner perceptions of program outcomes or agency trust, but did provide benefits such as increased landowner knowledge about birds. Neither outreach method was associated with more positive landowner post-program management intentions. Our findings underline the importance and potential of direct interactions between conservation biologists and landowners. These two forms of non-traditional outreach administered by biologists could be a worthwhile component of future conservation program evaluations on private lands.

Feather mite abundance varies but symbiotic nature of mite-host relationship does not differ between two ecologically dissimilar warblers.

Feather mites are obligatory ectosymbionts of birds that primarily feed on the oily secretions from the uropygial gland. Feather mite abundance varies within and among host species and has various effects on host condition and fitness, but there is little consensus on factors that drive variation of this symbiotic system. We tested hypotheses regarding how within-species and among-species traits explain variation in both (1) mite abundance and (2) relationships between mite abundance and host body condition and components of host fitness (reproductive performance and apparent annual survival). We focused on two closely related (Parulidae), but ecologically distinct, species: Setophaga cerulea (Cerulean Warbler), a canopy dwelling open-cup nester, and Protonotaria citrea (Prothonotary Warbler), an understory dwelling, cavity nester. We predicted that feather mites would be more abundant on and have a more parasitic relationship with P. citrea, and within P. citrea, females and older individuals would harbor greater mite abundances. We captured, took body measurements, quantified feather mite abundance on individuals' primaries and rectrices, and monitored individuals and their nests to estimate fitness. Feather mite abundance differed by species, but in the opposite direction of our prediction. There was no relationship between mite abundance and any measure of body condition or fitness for either species or sex (also contrary to our predictions). Our results suggest that species biology and ecological context may influence mite abundance on hosts. However, this pattern does not extend to differential effects of mites on measures of host body condition or fitness.

Mitochondrial genome of an Allegheny Woodrat (Neotoma magister).

The Allegheny woodrat (Neotoma magister) is endemic to the eastern United States. Population numbers have decreased rapidly over the last four decades due to habitat fragmentation, disease-related mortality, genetic isolation and inbreeding depression; however, effective management is hampered by limited genetic resources. To begin addressing this need, we sequenced and assembled the entire Allegheny woodrat mitochondrial genome. The genome assembly is 16,310 base pairs in length, with an overall base composition of 34% adenine, 27% thymine, 26% cytosine and 13% guanine. This resource will facilitate our understanding of woodrat population genetics and behavioral ecology.

Prevalence to Toxoplasma gondii and Sarcocystis spp. in a reintroduced fisher (Martes pennanti) population in Pennsylvania.

Understanding the role of disease in population regulation is important to the conservation of wildlife. We evaluated the prevalence of Toxoplasma gondii exposure and Sarcocystis spp. infection in 46 road-killed and accidentally trapper-killed fisher (Martes pennanti) carcasses collected and stored at -20 C by the Pennsylvania Game Commission from February 2002 to October 2008. Blood samples were assayed for T. gondii antibodies using the modified agglutination test (MAT, 1 : 25) and an indirect immunofluorescent antibody test (IFAT, 1 : 128). For genetic analysis, DNA samples were extracted from thoracic and pelvic limb skeletal muscle from each carcass to test for Sarcocystis spp. using 18s-rRNA PCR primers. Antibodies to T. gondii were found in 100% (38 of 38) of the fishers tested by MAT and in 71% (32 of 45) of the fishers tested by IFAT. PCR analysis revealed that 83% (38 of 46) of the fishers were positive for Sarcocystis spp. Sequence analysis of 7 randomly chosen amplicons revealed the fisher sarcocysts had a 98.3% to 99.1% identity to several avian Sarcocystis spp. sequences in GenBank. Data from our study suggest that a high percentage of fishers in Pennsylvania have been exposed to T. gondii and are infected with Sarcocystis spp.

Meningeal worm in a reintroduced elk population in Kentucky.

Meningeal worm (Parelaphostrongylus tenuis) has been implicated in the failure of several elk (Cervus elaphus) restoration attempts in the eastern United States. However, limited post-release monitoring and a paucity of published literature prevents a clear understanding of this parasite's role in past failures. During winters of 1997-2001, the Kentucky Department of Fish and Wildlife Resources translocated 1,044 elk from western states to eastern Kentucky (USA) in an effort to restore a free-ranging population. We monitored 521 radio-collared elk over 4 yr to determine the impact meningeal worm had on population establishment. Thirty (23%) of 129 non-capture related mortalities were attributed to meningeal worm. Twenty-two (73%) of these meningeal worm-caused mortalities were animals < 3 yr old. If younger elk born in Kentucky suffer higher mortality rates than older translocated elk, the population growth observed during the initial years of restoration may be temporary. Additional research is necessary to determine the influence meningeal worm will have on elk population growth in Kentucky.