Understanding the roles of philopatry and geography in determining genetic population structure is an important part of managing species characterized by metapopulations. In this study, we examined population structure, kinship, and runs of homozygosity in walleye (Sander vitreus) from Lake Champlain, a large, fragmented lake with four main spawning tributaries that form a metapopulation. Using microsatellite genotyping at 12 loci, we investigated population genetic structure among the four tributaries to examine how spawning site fidelity influenced pairwise genetic distances. Using a high-density Rapture dataset containing thousands of reference-aligned SNP genotypes, we estimated evidence of inbreeding based on runs of homozygosity (ROH) in Lake Champlain and compared findings to four other large walleye populations in North America. The Lamoille and Poultney Rivers were genetically distinct from the Missisquoi and Winooski Rivers, despite evidence of 10
Understanding bird migration at low altitudes is critical to evaluating risk of collision with obstacles. Recent advances in satellite tracking technologies allow quantifying use of low altitudes by small migrating birds with a high level of precision, allowing species-level inference into potential collision risk based on flight altitude. Scolopax minor (American Woodcock) is suspected to be a low-altitude migrant due to its frequent collisions with buildings, and subsequent mortality during migration may be contributing to population declines. We investigated migratory flight altitudes using satellite transmitters deployed on woodcock in 2020-2024 and examined how flight altitudes compare to the heights of common airspace obstacles. Each transmitter recorded a nocturnal GPS location with an altitude reading every 1-3 days during fall and spring migrations. We implemented a Bayesian hierarchical mixture model to identify whether locations were recorded on the ground or during flight, isolate measurement error, and describe the distribution of flight altitudes. We found that migrating woodcock fly at mean altitudes of 379 m above ground level, flying higher during spring (mean: 444 m, 95% credible interval: 333-578 m) than fall (338 m, 95% CRI: 267-423 m). Woodcock flight altitudes were frequently lower than could be observed using weather radar (27% of observations), and 57% of observations fell within the altitude range of >= 1 airspace obstacle. Our results suggest that woodcock fly at altitudes lower than reported for most nocturnal migrants, which likely contributes to their vulnerability to obstacle collisions. Scolopax minor provide an example of how vulnerability to obstacle collisions during nocturnal migratory flights are often species-specific, and mitigation efforts should incorporate measures aimed at reducing collisions during both diurnal stopovers and nocturnal migratory flights to effectively reduce bird collision mortality. center dot Collision with airspace obstacles (including buildings, wind turbines, and communication towers) is a major source of mortality for migratory birds.center dot In this study, we examined the flight altitudes of Scolopax minor (American Woodcock) equipped with GPS transmitters in 2020-2024 and compared their flight altitudes to common airspace obstacles.center dot We found that woodcock fly lower than most nocturnal migrants, and 57% of observations fell within the altitude range of at least one airspace obstacle.center dot These low-altitude flights may contribute to woodcocks' increased vulnerability to collisions with airspace obstacles. Comprender la migraci & oacute;n de las aves a bajas altitudes es fundamental para evaluar el riesgo de colisi & oacute;n con obst & aacute;culos. Los avances recientes en las tecnolog & iacute;as de rastreo satelital permiten cuantificar con alta precisi & oacute;n el uso de bajas altitudes por parte de aves migratorias peque & ntilde;as, lo que permite hacer inferencias a nivel de especie sobre el riesgo potencial de colisi & oacute;n seg & uacute;n la altitud de vuelo. Se sospecha que Scolopax minor es un migrante de baja altitud debido a sus frecuentes colisiones con edificios, y la mortalidad resultante durante la migraci & oacute;n podr & iacute;a estar contribuyendo al declive de su poblaci & oacute;n. Investigamos las altitudes de vuelo migratorio utilizando transmisores satelitales instalados en individuos de S. minor entre 2020 y 2024 y examinamos c & oacute;mo se comparan estas altitudes con la altura de los obst & aacute;culos comunes en el espacio a & eacute;reo. Cada transmisor registr & oacute; una ubicaci & oacute;n GPS nocturna con una lectura de altitud cada 1 a 3 d & iacute;as durante las migraciones de oto & ntilde;o y primavera. Implementamos un modelo jer & aacute;rquico bayesiano de mezcla para identificar si las ubicaciones se registraron en el suelo o en vuelo, aislar el error de medici & oacute;n y describir la distribuci & oacute;n de las altitudes de vuelo. Encontramos que los individuos migratorios de S. minor vuelan a una altitud media de 379 m sobre el nivel del suelo, volando m & aacute;s alto en primavera (media: 444 m, intervalo de credibilidad del 95%: 333-578 m) que en oto & ntilde;o (338 m, ICR 95%: 267-423 m). Las altitudes de vuelo de S. minor fueron frecuentemente m & aacute;s bajas de lo que podr & iacute;a detectarse con radar meteorol & oacute;gico (27% de las observaciones), y el 57% de las observaciones se encontraron dentro del rango de altitud de >= 1 obst & aacute;culo a & eacute;reo. Nuestros resultados sugieren que S. minor vuela a altitudes m & aacute;s bajas que las reportadas para la mayor & iacute;a de los migrantes nocturnos, lo que probablemente contribuye a su vulnerabilidad ante colisiones con obst & aacute;culos. S. minor es un ejemplo de c & oacute;mo la vulnerabilidad a las colisiones con obst & aacute;culos durante los vuelos migratorios nocturnos suele ser espec & iacute;fica de cada especie, y los esfuerzos de mitigaci & oacute;n deber & iacute;an incluir medidas dirigidas a reducir las colisiones tanto durante las paradas diurnas como en los vuelos migratorios nocturnos para disminuir eficazmente la mortalidad por colisi & oacute;n de estas aves.
Autonomous recording units are increasingly being used to monitor wildlife on large geographic and temporal scales, paired with machine learning (ML) to automate detection of wildlife. However, false positive detections from ML classifiers can result in erroneous ecological models that can lead to misguided management and conservation actions. We used a two-stage general approach to understand and reduce false positive detections, a technique in which outputs of the primary classification model are passed to a secondary classification model to yield the probability that a detection from the primary model is a true positive detection. This approach is demonstrated on two open-source models that detect Ruffed Grouse (Bonasa umbellus). We analyzed over 9500 h of acoustic data collected in 2022-2023 from the Green Mountain National Forest in Vermont, USA, and found the two models detected different types of acoustic signals associated with differing life history traits. The first model yielded 4106 detections (71.5 % true positives) while the second model yielded 524 detections (17.0 % true positives). Secondary logistic regression models separated true positives and false positives with high accuracy (84.5 % and 89.8 % respectively). Our findings go beyond improving Ruffed Grouse monitoring and conservation efforts to, more broadly, illustrate how two-stage ML approaches can improve the use of model-derived detections in wildlife research.
Lake trout (Salvelinus namaycush) populations in many northern North American large lake systems have been substantially reduced or extirpated due to overfishing, habitat loss, and introduction of invasive species. Following reductions in fishing pressure and successful suppression of sea lamprey, attempts have been made to restore self-sustaining populations into most of these waters but success has been slow and limited. In contrast, lake-wide lake trout restoration occurred abruptly and rapidly in Lake Champlain after 40 years of stocking, with robust, widespread, and sustained wild recruitment observed from the 2012 cohort onwards. We sought to better understand the dynamics of the recovery success in Lake Champlain using a multi-year tissue dataset, in combination with a recently-designed genotyping panel and close-kin mark-recapture, to quantify the performance (i. e., survival and reproductive success) of stocking sources and strategies with an eye towards informing restoration programs in other systems. We also assessed the overall abundance of adult fish and parental dynamics associated with wild recruitment. Our results indicate that adult survival is remarkably high and overall abundance is low compared to other large lake systems in similar latitudes, with the vast majority of wild recruitment genetically traceable to the Seneca strain fish historically stocked by New York State. We observed little evidence of hybridization between the two strains and close-kin mark-recapture estimates indicated that approximately 20 % of the adult population was contributing to successful recruitment on a regular basis. Ultimately, our results point to a growing wild population that has the potential to become self-sustaining.
As one of the original National Fish Habitat Partnerships, the Eastern Brook Trout Joint Venture (EBTJV) was formed out of a concern for loss of Brook Trout Salvelinus fontinalis, one of North America's most revered fishes, in its eastern native range. More than two decades later, this volunteer-led initiative continues to thrive through a strong partnership of federal, state, tribal, and nongovernmental organizations to advance Brook Trout conservation. Focused primarily upon protection and enhancement of habitats, the EBTJV supports on-the-ground habitat projects directly, while also advancing Brook Trout conservation via collection and dissemination of range-wide salmonid occupancy data, comprehensive outreach efforts, and expansion of scientific partnerships. Going forward, the EBTJV will continue to explore opportunities to expand its impact as the hub for Brook Trout research and management and achieve its vision of "healthy coldwater systems with fishable Brook Trout populations throughout their historic eastern geographic range."
