No abstract

In the western United States, wolverines (Gulo gulo) typically occupy high‐elevation habitats. Because wolverine populations occur in vast, remote areas across multiple states, biologists have an imperfect understanding of this species' current distribution and population status. The historical extirpation of the wolverine, a subsequent period of recovery, and the lack of a coordinated monitoring program in the western United States to determine their current distribution further complicate understanding of their population status. We sought to define the limits to the current distribution, identify potential gaps in distribution, and provide a baseline dataset for future monitoring and analysis of factors contributing to changes in distribution of wolverines across 4 western states. We used remotely triggered camera stations and hair snares to detect wolverines across randomly selected 15‐km × 15‐km cells in Idaho, Montana, Washington, and Wyoming, USA, during winters 2016 and 2017. We used spatial occupancy models to examine patterns in wolverine distribution. We also examined the influence of proportion of the cell containing predicted wolverine habitat, human‐modified land, and green vegetation, and area of the cluster of contiguous sampling cells. We sampled 183 (28.9%) of 633 cells that comprised a suspected wolverine range in these 4 states and we detected wolverines in 59 (32.2%) of these 183 sampled cells. We estimated that 268 cells (42.3%; 95% CI = 182–347) of the 633 cells were used by wolverines. Proportion of the cell containing modeled wolverine habitat was weakly positively correlated with wolverine occupancy, but no other covariates examined were correlated with wolverine occupancy. Occupancy rates (ψ) were highest in the Northern Continental Divide Ecosystem (ψ range = 0.8–1), intermediate in the Cascades and Central Mountains of Idaho (ψ range = 0.4–0.6), and lower in the Greater Yellowstone Ecosystem (ψ range = 0.1–0.3). We provide baseline data for future surveys of wolverine along with a design and protocol to conduct those surveys. © 2020 The Authors. The Journal of Wildlife Management published by Wiley Periodicals, Inc. on behalf of The Wildlife Society.

We used radar to count numbers of Marbled Murrelets (Brachyramphus marmoratus) flying inland within 10 river drainages on the Olympic Peninsula, Washington, during 1998–2000. We tested whether the numbers of murrelets entering drainages could be predicted from the amount and spatial configuration of low-elevation, late-seral forest (potential murrelet nesting habitat) within drainages. The maximal number of murrelet radar targets was positively correlated with the amount of late-seral forest in each of the three years sampled; this relationship persisted in 1999 and 2000 when controlling for drainage size. Murrelet radar counts were not correlated with the combined amounts of harvested, developed, and agricultural lands in any year. Numbers of murrelets increased as the amount of core area of late-seral forest and proximity of patches increased, and decreased with increasing amounts of edge of late-seral patches. Numbers were not correlated with the percent of late-seral forest, patch density, patch size, road density, or the overall diversity of all habitat types within landscapes. Neither the maximal nor the mean number of inbound Marbled Murrelets differed among years; the effect of year was small relative to the effect of habitat on murrelet numbers. Our results suggest that changes in the amount or distribution of nesting habitat should result in detectable changes in murrelet numbers at the scale of individual drainages. Thus, the amount and distribution of nesting habitat may play a role in the regulation of Marbled Murrelet populations, supporting the contention that providing nesting habitat is an effective conservation and restoration technique for this species.Relaciones a Escala del Paisaje entre la Abundancia de Brachyramphus marmoratus y la Distribución de Hábitat de NidificaciónResumen. Durante 1998–2000 utilizamos radares para contar el número de individuos de Brachyramphus marmoratus que volaron tierra adentro a lo largo de 10 cuencas de ríos que desaguan en la Península Olímpica, Washington, USA. Evaluamos si el número de individuos de B. marmoratus que entran por las cuencas puede ser predicho por la cantidad y configuración espacial de bosques de baja elevación que se encuentran en estadíos sucesionales tardíos (potencial hábitat de nidificación para estas aves) en cada cuenca. En cada uno de los tres años, el máximo número de individuos de B. marmoratus detectados estuvo positivamente correlacionado con la cantidad de bosque sucesional tardío; luego de controlar por el área de las cuencas esta relación persistió en 1999 y 2000. Durante todos los años, los conteos de B. marmoratus mediante radares no se correlacionaron con la cantidad combinada de tierras cosechadas, desarrolladas y agrícolas. El número de individuos de B. marmoratus aumentó con el área núcleo de bosque sucesional tardío y con el aumento de la proximidad entre parches, y decreció con el aumento de la cantidad de borde en los parches sucesionales tardíos. El número de aves no se correlacionó con el porcentaje de bosque sucesional tardío, densidad y área de parches, densidad de calles, ni diversidad total de todos los tipos de hábitats en el paisaje. Ni el número máximo ni el promedio de individuos de B. marmoratus que volaron en dirección tierra adentro diferió entre años; el efecto del año fue pequeño en comparación con el efecto del hábitat o del número de aves. Nuestros resultados sugieren que los cambios en la cantidad o distribución de hábitat para la nidificación deberían resultar en cambios detectables en el número de individuos de B. marmoratus a la escala individual de cada cuenca. Por lo tanto, la cantidad y distribución de hábitat para nidificación puede jugar un papel importante en la regulación de poblaciones de B. marmoratus, lo cual apoya la idea que proveer de hábitat para nidificación es una técnica efectiva para la conservación y restauración de esta especie.

No abstract

The persistence of small populations is influenced by genetic structure and functional connectivity. We used two network-based approaches to understand the persistence of the northern Idaho ground squirrel (Urocitellus brunneus) and the southern Idaho ground squirrel (U. endemicus), two congeners of conservation concern. These graph theoretic approaches are conventionally applied to social or transportation networks, but here are used to study population persistence and connectivity. Population graph analyses revealed that local extinction rapidly reduced connectivity for the southern species, while connectivity for the northern species could be maintained following local extinction. Results from gravity models complemented those of population graph analyses, and indicated that potential vegetation productivity and topography drove connectivity in the northern species. For the southern species, development (roads) and small-scale topography reduced connectivity, while greater potential vegetation productivity increased connectivity. Taken together, the results of the two network-based methods (population graph analyses and gravity models) suggest the need for increased conservation action for the southern species, and that management efforts have been effective at maintaining habitat quality throughout the current range of the northern species. To prevent further declines, we encourage the continuation of management efforts for the northern species, whereas conservation of the southern species requires active management and additional measures to curtail habitat fragmentation. Our combination of population graph analyses and gravity models can inform conservation strategies of other species exhibiting patchy distributions.