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Dispersal is a key demographic process, ultimately responsible for genetic connectivity among populations. Despite its importance, quantifying dispersal within and between populations has proven difficult for many taxa. Even in passerines, which are among the most intensely studied, individual movement and its relation to gene flow remains poorly understood. In this study we used two parallel genetic approaches to quantify natal dispersal distances in a Neotropical migratory passerine, the black-capped vireo. First, we employed a strategy of sampling evenly across the landscape coupled with parentage assignment to map the genealogical relationships of individuals across the landscape, and estimate dispersal distances; next, we calculated Wright's neighborhood size to estimate gene dispersal distances. We found that a high percentage of captured individuals were assigned at short distances within the natal population, and males were assigned to the natal population more often than females, confirming sex-biased dispersal. Parentage-based dispersal estimates averaged 2400m, whereas gene dispersal estimates indicated dispersal distances ranging from 1600-4200 m. Our study was successful in quantifying natal dispersal distances, linking individual movement to gene dispersal distances, while also providing a detailed look into the dispersal biology of Neotropical passerines. The high-resolution information was obtained with much reduced effort (sampling only 20% of breeding population) compared to mark-resight approaches, demonstrating the potential applicability of parentage-based approaches for quantifying dispersal in other vagile passerine species.

Bird song is crucial for attracting mates and defending territories, but different types of song or different singing behaviours may be involved in acquiring or maintaining each resource. Furthermore, male songbirds may adjust when and where they sing throughout the breeding season, depending on their breeding stage. However, such relationships remain untested in several avian taxa. Here, we studied male Bermuda white‐eyed vireos Vireo griseus bermudianus, a passerine with two distinct song types (discrete and rambling), to test the mate attraction and territory defence hypotheses. We compare song production and song perch height among different stages of the breeding season and during the non‐breeding season. We show that male vireos produce both song types during the breeding and non‐breeding seasons, suggesting dual roles in mate choice and territorial defence. Song production did not differ significantly between the breeding and non‐breeding seasons, but, within the breeding season, males without nesting duties sang significantly more songs than males with nesting duties. Song perch height was higher during the breeding season versus non‐breeding season, among males without nesting duties compared to males with nesting duties, and when males produced discrete versus rambling songs. Our findings suggest that male vireos increase their conspicuousness to prospecting females by increasing song production and song perch height, and that they sing during the breeding and non‐breeding seasons to defend year‐round territories. Collectively, our study supports the mate attraction and territory defence hypotheses of bird song.

Approximately two thirds of migratory songbirds in eastern North America negotiate the Gulf of Mexico (GOM), where inclement weather coupled with no refueling or resting opportunities can be lethal. However, decisions made when navigating such features and their consequences remain largely unknown due to technological limitations of tracking small animals over large areas. We used automated radio telemetry to track three songbird species (Red-eyed Vireo, Swainson’s Thrush, Wood Thrush) from coastal Alabama to the northern Yucatan Peninsula (YP) during fall migration. Detecting songbirds after crossing ∼1,000 km of open water allowed us to examine intrinsic (age, wing length, fat) and extrinsic (weather, date) variables shaping departure decisions, arrival at the YP, and crossing times. Large fat reserves and low humidity, indicative of beneficial synoptic weather patterns, favored southward departure across the Gulf. Individuals detected in the YP departed with large fat reserves and later in the fall with profitable winds, and flight durations (mean = 22.4 h) were positively related to wind profit. Age was not related to departure behavior, arrival, or travel time. However, vireos negotiated the GOM differently than thrushes, including different departure decisions, lower probability of detection in the YP, and longer crossing times. Defense of winter territories by thrushes but not vireos and species-specific foraging habits may explain the divergent migratory behaviors. Fat reserves appear extremely important to departure decisions and arrival in the YP. As habitat along the GOM is degraded, birds may be limited in their ability to acquire fat to cross the Gulf.

Nest predation is a major limiting factor for songbird productivity, including the federally endangered black-capped vireo (Vireo atricapilla). However, nest predator information is limited across the range of the black-capped vireo in central and southwest Texas. We monitored nests in 3 counties within the breeding range of black-capped vireos in Texas in 2008 and 2009 and used continuous recording digital video cameras to record predation events. We video-monitored 115 nests and documented 39 predation events by at least 9 predator species. Overall, we observed avian species (51%, n = 39), specifically brown-headed cowbirds (Molothrus ater, n = 12), and snakes (26%, n = 39) as the most frequent nest predators. The estimated daily nest survival rate during the laying and incubation stage was 0.985 (95% CI = 0.967—0.993) and 0.944 (95% CI = 0.921—0.961) during the nestling stage. In addition, we analyzed models of predator-specific nest predation using multinomial logistic regression. Effect of nest height on predation rate was significant for snakes; nest stage was significant for nests depredated by avian predators. By identifying and increasing our knowledge of nest predators and vegetation characteristics associated with greater risk of predation in multiple locations within the black-capped vireo's range, we can effectively manage habitat to benefit recovery efforts of the species.

AbstractThe Black-capped Vireo (Vireo atricapilla) was delisted from the U.S. Endangered Species List by the United States Fish and Wildlife Service (USFWS) in 2018. As part of the USFWS Post-Delisting Monitoring Plan, nest searching and monitoring of vireo nests were completed in 2021 and 2022 to provide an estimate on parasitism and nest success in the region. Field work for this study took place in Kickapoo Cavern State Park in the western Edwards Plateau of Texas. The two field seasons were characterized by mild drought conditions in 2021 and exceptional drought conditions in 2022. The logistic exposure method was used to quantify the relative success vireo nests had in each year. Nests found in 2021 (n = 18) had a daily survival rate (DSR) of 0.96 and an overall chance of survival from nest building to fledging of 40.5%. Nests found in 2022 (n = 15) had a DSR of 0.88 and an annual survival rate of 4.6%. Additionally, in 2021 vireos only nested in Ashe Juniper (Juniperus ashei) 16% (n = 3) of the time, whereas in 2022 juniper was utilized in 46% (n = 7) of nests. This is of particular importance because juniper removal is one method used to help enhance potential Black-capped Vireo habitat. Black-capped Vireo nests were parasitized by Brown-headed Cowbirds (Molothrus ater) 33% (n = 6) and 47% (n = 7) of the time in 2021 and 2022, respectively. The results of this study will help inform management decisions for Black-capped Vireo populations as historic drought conditions likely become more common under changing global climates.

Multiplexed single-cell RNA-seq analysis of multiple samples using pooling is a promising experimental design, offering increased throughput while allowing to overcome batch variation. To reconstruct the sample identify of each cell, genetic variants that segregate between the samples in the pool have been proposed as natural barcode for cell demultiplexing. Existing demultiplexing strategies rely on availability of complete genotype data from the pooled samples, which limits the applicability of such methods, in particular when genetic variation is not the primary object of study. To address this, we here present Vireo, a computationally efficient Bayesian model to demultiplex single-cell data from pooled experimental designs. Uniquely, our model can be applied in settings when only partial or no genotype information is available. Using pools based on synthetic mixtures and results on real data, we demonstrate the robustness of Vireo and illustrate the utility of multiplexed experimental designs for common expression analyses.

For species at risk of decline or extinction in source-sink systems, sources are an obvious target for habitat protection actions. However, the way in which source habitats are identified and prioritized can reduce the effectiveness of conservation actions. Although sources and sinks are conceptually defined using both demographic and movement criteria, simplifications are often required in systems with limited data. To assess the conservation outcomes of alternative source metrics and resulting prioritizations, we simulated population dynamics and extinction riskfor 3 endangered species. Using empirically based habitat population models, we linked habitat maps with measured site- or habitat-specific demographic conditions, movement abilities, and behaviors. We calculated source-sink metrics over a range of periods of data collection and prioritized consistently high-output sources for conservation. We then tested whether prioritized patches identified the habitats that most affected persistence by removing them and measuring the population response. Conservation decisions based on different source-sink metrics and durations of data collection affected species persistence. Shorter time series obscured the ability of metrics to identify influential habitats, particularly in temporally variable and slowly declining populations. Data-rich source-sink metrics that included both demography and movement information did not always identify the habitats with the greatest influence on extinction risk. In some declining populations, patch abundance better predicted influential habitats for short-term regionalpersistence. Because source-sink metrics (i.e., births minus deaths; births and immigrations minus deaths and emigration) describe net population conditions and cancel out gross population counts, they may not adequately identify influential habitats in declining populations. For many nonequilibrium populations, new metrics that maintain the counts of individual births, deaths, and movement may provide additional insight into habitats that most influence persistence. Para las especies en riesgo de declinación o extinción en sistemas de fuente - sumidero, las fuentes son un objetivo obvio para las acciones de protección del habitat. Sin embargo, la manera en la que se identifican y priorizan los habitats fuente puede reducir la efectividad de las acciones de conservación. Aunque las fuentes y sumideros se definen conceptualmente usando tanto los criterios de movimiento como los demográficos, generalmente se requieren simplificaciones en sistemas con datos limitados. Para evaluar los resultados de conservación de las medidas alternativas de fuentes y las priorizaciones resultantes, simulamos dinámicas poblacionales y el riesgo de extinción de tres especies en peligro de extinción. Con el uso de modelos de población basados en el habitat, relacionamos los mapas de habitat con las condiciones demográficas específicas de sitio o de habitat, las habilidades de movimiento, y los comportamientos. Calculamos las medidas de fuente - sumidero en una gama de periodos de recolección de datos y priorizamos las fuentes constantes de producción alta para la conservación. Después probamos si los fragmentos priorizados identificaron a los habitats que más afectaron la persistencia al removerlos y medir la respuesta de la población. Las decisiones de conservación basadas en diferentes medidas de fuente - sumidero y con recolecciones de datos de diferente duración afectaron la persistencia de las especies. Las series de tiempo más cortas dificultaron la habilidad de las medidas para identificar los habitats influyentes, particularmente en poblaciones con variabilidad temporal y con declinación lenta. Las medidas de fuente - sumidero ricas en datos que incluyeron la información demográfica y de movimiento no siempre identificaron los habitats con la mayor influencia sobre el riesgo de extinción. En algunas poblaciones declinantes, la abundancia de fragmentos predijo de mejor manera los habitats influyentes para la persistencia regional a corto plazo. Ya que las medidas de fuente - sumidero (es decir, nacimientos menos muertes; nacimientos e inmigraciones menos muertes y emigraciones) describen las condiciones netas de la población y anulan los conteos poblacionales brutos, puede que no identifiquen adecuadamente los habitats influyentes en poblaciones declinantes. Para muchas poblaciones que no se encuentran en equilibrio, las nuevas medidas que mantengan los conteos de nacimientos, muertes y movimientos individuales pueden proporcionar un entendimiento adicional de los habitats que más influyen sobre la persistencia. 对于源〜汇系统中面临种群下降和灭绝风险的物种，栖息地保护行动的一个显著目标是对“源” 的保护。然而，对“源” 栖息地的识别和保护优先排序的方式可能会降低保护行动的有效。“源” 和“汇”理论上是根据 种群统计和迁移参数而定义，但数据有限的系统常常需要对其简化。为评估备选源的参数与其保护优先区的保 护成效, 我们模拟了三个瀕危物种的种群动态和灭绝风险。我们还用基于经验的栖息地种群模型，将栖息地地图 与測定的位点或栖息地特异性的种群统计参数、迁移能力和行为进行结合。我们计算了不同数据收集周期的 源〜参歡并优先保护有持续高输出的“源”。接下来通过去除优先保护的斑块并测定物种的响应，我们检验了 这些斑块是否能代表対物种续存影响最大的栖息地。基于不同源〜汇参数和数据收集周期的保护决策会影响物 种续存。短时间序列的数据阻碍了对重要栖息地度量的能力，特別是对短期内波动和緩慢下降的种群而言。包 含了种群统计和移动信息丰富的源~汇参数，并非能常常确定对物种灭绝风险影响最大的栖息地。在ー些下降 种群中，斑块丰度更能预测物种在短时间内区域续存的重要栖息地。源~汇参数(如出生减去死亡;出生和迁入 减去死亡和迁出) 描述种群净变化，抵消了总的种群数量计数，因此它们或许不能充分地确定下降种群的重要栖 息地。对许多非平衡的种群来说，可以对个体的出生、死亡、迁移连续计数的新参数或能帮助我们更好地了解 対物种续存影响最大的栖息地。

The brown-headed cowbird (Molothrus ater; cowbird) is unique among North American blackbirds (Icteridae) because it is managed to mitigate the negative effects on endangered songbirds and economic losses in agricultural crops. Cowbird brood parasitism can further affect species that are considered threatened or endangered due to anthropogenic land uses. Historically, cowbirds have often been culled without addressing ultimate causes of songbird population declines. Similar to other North American blackbirds, cowbirds depredate agricultural crops, albeit at a lower rate reported for other blackbird species. Conflicting information exists on the extent of agricultural damage caused by cowbirds and the effectiveness of mitigation measures for application to management. In this paper, we reviewed the progress that has been made in cowbird management from approximately 2005 to 2020 in relation to endangered species. We also reviewed losses to the rice (Oryza sativa) crop attributed to cowbirds and the programs designed to reduce depredation. Of the 4 songbird species in which cowbirds have been managed, both the Kirtland’s warbler (Dendroica kirtlandii) and black-capped vireo (Vireo atricapilla) have been removed from the endangered species list following population increases in response to habitat expansion. Cowbird trapping has ceased for Kirtland’s warbler but continues for the vireo. In contrast, least Bell’s vireo (V. bellii pusillus) and southwestern willow flycatcher (Empidonax traillii extimus) still require cowbird control after modest increases in suitable habitat. Our review of rice depredation by cowbirds revealed models that have been created to determine the number of cowbirds that can be taken to decrease rice loss have been useful but require refinement with new data that incorporate cowbird population changes in the rice growing region, dietary preference studies, and current information on population sex ratios and female cowbird egg laying. Once this information has been gathered, bioenergetic and economic models would increase our understanding of the damage caused by cowbirds.

For signal divergence to drive speciation, receivers should perceive structural differences in divergent signals; similar-structured signals from closer relatives are expected to elicit stronger responses than dissimilar signals from distant relatives. Two mechanisms can affect receiver responses to passerine song: (1) sympatric song familiarity and (2) an innate auditory template used to assess acoustic similarity. We examined the role of acoustic similarity by comparing behavioral responses of male Bermuda White-eyed Vireos (Vireo griseus bermudianus) to playback of the songs of allopatric species from across the family Vireonidae. Phylogenetic distance between the focal and stimulus species predicted response strength. Males uttered fewer vocalizations, had fewer speaker flyovers, and remained farther from the speaker during playback of the songs of more distantly related vireos. We then tested whether structural similarity of playback songs, as defined by three phylogenetically conserved song traits, explained these relationships. As predicted, males uttered fewer vocalizations, had fewer speaker flyovers, and remained farther from the speaker in response to more dissimilar songs. Collectively, our results suggest that male Bermuda Vireos perceive and respond to interspecies variation in the phylogenetically conserved song traits of allopatric species of vireos. This suggests that song divergence, and the ability to distinguish divergent songs, reinforces reproductive isolation and competitor exclusion. Para que la divergencia de señales conduzca a la especiación, los receptores deben percibir las diferencias estructurales de señales divergentes. Se espera que las señales de estructuras similares de parientes más cercanos provoquen respuestas más fuertes que las señales disimilares de parientes distantes. Dos mecanismos pueden afectar las respuestas de los receptores al canto de paserinas: (1) familiaridad de canto simpátrico y (2) una plantilla auditiva innata que se usa para determinar la similitud acústica. Examinamos el papel de la similitud acústica por medio de comparaciones de respuestas de comportamiento en machos del vireo Vireo griseus bermudianus a grabaciones de cantos de especies alopátricas de la familia Vireonidae. La distancia filogenética entre las especies focal y estímulo predicen la fuerza de la respuesta. Los machos completaron menos vocalizaciones, tuvieron menos sobrevuelos a la bocina y permanecieron más lejos durante el tiempo en que se tocó la grabación de los vireos más distantemente emparentados. Cuando sometimos a prueba la similitud estructural de los cantos grabados, tal y como lo definen tres características filogenéticamente conservadas de los cantos, éstas explicaron esas relaciones. Como lo predecimos, los machos completaron menos vocalizaciones, tuvieron menos sobrevuelos a la bocina y permanecieron más lejos en respuesta a los cantos más disímiles. En conjunto, nuestros resultados sugieren que los machos de este vireo perciben y responden a variación interespecífica en las características del canto filogenéticamente conservadas de las especies de vireos alopátricos. Esto sugiere que la divergencia del canto, y la capacidad de distinguir cantos divergentes, refuerza el aislamiento reproductivo y la exclusión competitiva.

Understanding the relative impact of climate change and land cover change on changes in avian distribution has implications for the future course of avian distributions and appropriate management strategies. Due to the dynamic nature of climate change, our goal was to investigate the processes that shape species distributions, rather than the current distributional patterns. To this end, we analyzed changes in the distribution of Eastern Wood Pewees (Contopus virens) and Red‐eyed Vireos (Vireo olivaceus) from 1997 to 2012 using Breeding Bird Survey data and dynamic correlated‐detection occupancy models. We estimated the local colonization and extinction rates of these species in relation to changes in climate (hours of extreme temperature) and changes in land cover (amount of nesting habitat). We fit six nested models to partition the deviance explained by spatial and temporal components of land cover and climate. We isolated the temporal components of environmental variables because this is the essence of global change. For both species, model fit was significantly improved when we modeled vital rates as a function of spatial variation in climate and land cover. Model fit improved only marginally when we added temporal variation in climate and land cover to the model. Temporal variation in climate explained more deviance than temporal variation in land cover, although both combined only explained 20% (Eastern Wood Pewee) and 6% (Red‐eyed Vireo) of temporal variation in vital rates. Our results showing a significant correlation between initial occupancy and environmental covariates are consistent with biological expectation and previous studies. The weak correlation between vital rates and temporal changes in covariates indicated that we have yet to identify the most relevant components of global change influencing the distributions of these species and, more importantly, that spatially significant covariates are not necessarily driving temporal shifts in avian distributions. We analyzed changes in the distribution of Eastern Wood Pewees and Red‐eyed Vireos from 1997 to 2012 using dynamic correlated‐detection occupancy models. Temporal variation in climate explained marginally more deviance than temporal variation in land cover. The weak correlation between temporal changes in covariates and changes in bird distributions indicated that spatially significant covariates are not necessarily driving temporal shifts in avian distributions.