Urocitellus brunneus (northern Idaho ground squirrel) has a geographic range of approximately 1,600 km² in west-central Idaho. It was listed as Threatened under the US Endangered Species Act in 2000. To assist recovery efforts, we tested three hypotheses that might explain its rarity: 1) specialization on a now uncommon habitat; 2) competition with a larger congener, U. columbianus (Columbian ground squirrel); and 3) anthropogenic impacts. We explored the habitat specialization hypothesis by comparing attributes of sites occupied exclusively by each species with areas occupied alternately by each. Sites occupied by U. brunneus had significantly more bare ground; shallower, rockier, harder soils; higher soil temperatures during the active season; less plant cover; shorter vegetation; lower net annual aboveground productivity; and fewer shrubs than sites occupied by U. columbianus. Discriminant analysis showed U. brunneus could occupy some areas used by U. columbianus, but U. columbianus seldom occupied areas occupied by U. brunneus. U. brunneus also occurred in earlier successional communities and could occupy mesic meadows with high water tables not utilized by U. columbianus. In field observations and arena trials, U. brunneus avoided U. columbianus. In two removal experiments U. brunneus expanded into areas from which U. columbianus had been removed, but vacated when U. columbianus returned. Anthropogenic impacts included habitat conversion, conifer invasion of meadows resulting from timber management and fire suppression practices, systematic poisoning, target shooting, and invasive species; grazing appears to have mixed impacts. U. brunneus is rare due to a combination of habitat specialization, competition, and anthropogenic impacts.

Tardigrades live in many ecosystems, but local dispersal mechanisms and the influence of ecological gradients on tardigrade communities are not fully understood. Here we examine tardigrade communities in nests of the red tree vole (Arborimus longicaudus True), an arboreal mammal occupying the canopy of coniferous forests in western Oregon and northwestern California. We found 12 species of tardigrades from resin ducts sampled from 43 nests along a transect that spanned the east-west range of the red tree vole in southern Oregon. Tardigrade occurrence was more likely in larger trees and species numbers were significantly higher in areas that received more precipitation. At sites where they occurred, tardigrades were more abundant in red tree vole nests at greater heights within the forest canopy. Of the 12 species of tardigrades that were found, seven have not been previously reported in Oregon. Our results suggest that tardigrades in forest canopies in the Pacific Northwest are affected by regional precipitation gradients as well as local environmental variables, and that nest building by small mammals may facilitate dispersal of tardigrades within the forest canopy.

The streaked horned lark (Eremophila alpestris strigata) is a federally-threatened ground-nesting passerine. We investigated range-wide patterns of dispersal by analyzing resight records between 2002 and 2016 from four regions (South Puget Lowlands, Lower Columbia River, Washington Coast, Willamette Valley) and determined frequency and distances of dispersal events for second-year (SY, natal dispersal) and after second-year adults (ASY, breeding dispersal). Of 148 SY adults originally banded as dependent young and subsequently resighted as breeders, 111 (75%) returned to their natal breeding site and 37 (25%) dispersed to new sites. Among the latter, only two individuals dispersed to a different region. For natal dispersers that left their natal site, mean dispersal distance was 20.5 ± 26.8 km (± SD, median = 11.7 km) although most (73%) travelled less than 15 km. Female natal dispersers moved to new sites more frequently than males (29% versus 20%), which is consistent with typical female-biased dispersal in birds. In contrast to SY birds, ASY birds largely remained at the site where they spent their first potential breeding season (68 of 71; 96%). No adults left the region in which they first bred. These patterns of natal dispersal, emigration, and immigration can inform conservation planning by contributing to priorities for land protection.

The Trinity Alps is a compact glaciated subrange of the Klamath Mountains in northwest California with elevations < 2,750 m making it a unique location in the western US to study glacier change. We examined glacier change since the last Little Ice Age advance in the late 19th century by mapping historic glacier areas using clearly defined moraines. At least six glaciers existed in the Trinity Alps around the 1880s and estimated glacier cover was at least 55.4 ha (0.554 km²). We tracked changes in two glaciers and two perennial snowfields since that time. Total glacier area decreased by 79% (43.8 ha to 9.1 ha) from the 1880s to 1994. By 2013, glacier area decreased another 7% of the 1880s area to 6.0 ha. Overall, retreat was similar for Salmon Glacier (–89%) and Grizzly Glacier (–84%), but since 1994 Salmon retreat has been much faster, 53% versus 16% for Grizzly. The extended 2012 to 2016 drought resulted in catastrophic retreat of both glaciers such that by 2015 Salmon Glacier disappeared and Grizzly Glacier retreated to 1.67 ha and partially stagnated, a –97% loss of total glacier area since the 1880s. Two snowfields (3.02 ha total area in 1955) were tracked since 1955, the Mirror Lake snowfield disappeared by the summer of 2013 and the Canyon Creek snowfield disappeared by October 2014. The unusually warm summer temperatures since 2005 combined with extremely low winter precipitation from 2013 to 2015 caused rapid retreat and near elimination of the Trinity Alps perennial snow and ice threatening local biodiversity that depends on these features.

This study sought to document potential insect pollinators of Neil Rock checkerbloom, Sidalcea hickmanii ssp. petraea (Malvaceae) and measure the effects of pollinator exclusion and plant type on flower, fruit, and seed production. Prior to this study, the pollination requirements of this gynodioecious plant were unknown and potentially complicated by its hermaphroditic and female-only plant types. Analyses showed that pollinator exclusion had no effect on mean number of flowers produced per raceme but significantly reduced the mean number of fruits produced per raceme and mean number of fruits produced per flower, as well as the mean number of seeds produced per raceme in both female-only and hermaphroditic plants. These results suggested that S. hickmanii ssp. petraea is pollinator dependent. Six orders (Hymenoptera, Coleoptera, Homoptera, Lepidoptera, Diptera, and Hemiptera) representing 29 taxa of insects (primarily Hymenoptera – notably Osmia and Hoplitis, and Coleoptera – notably Anthonomus and Trichodes) were collected from flowering S. hickmanii ssp. petraea plants. Adult Anthonomus weevils were observed selectively feeding on the developing fruits of hermaphroditic over female-only plants. This selective predation may have a significant impact on the maintenance of gynodioecy in this endemic, narrowly-isolated subspecies of Sidalcea hickmanii.

Estimating salmonid habitat capacity upstream of a barrier can inform priorities for fisheries conservation. Scott Dam in California's Eel River is an impassable barrier for anadromous salmonids. With Federal dam relicensing underway, we demonstrated recolonization potential for upper Eel River salmonid populations by estimating the potential distribution (stream-km) and habitat capacity (numbers of parr and adults) for winter steelhead trout (Oncorhynchus mykiss) and fall Chinook salmon (O. tshawytscha) upstream of Scott Dam. Removal of Scott Dam would support salmonid recovery by increasing salmonid habitat stream-kms from 2 to 465 stream-km for steelhead trout and 920 to 1,071 stream-km for Chinook salmon in the upper mainstem Eel River population boundaries, whose downstream extents begin near Scott Dam and the confluence of South Fork Eel River, respectively. Upstream of Scott Dam, estimated steelhead trout habitat included up to 463 stream-kms for spawning and 291 stream-kms for summer rearing; estimated Chinook salmon habitat included up to 151 stream-kms for both spawning and rearing. The number of returning adult estimates based on historical count data (1938 to 1975) from the South Fork Eel River produced wide ranges for steelhead trout (3,241 to 26,391) and Chinook salmon (1,057 to 10,117). An approach that first estimated juvenile habitat capacity and then used subsequent life stage survival rates yielded 1,281 (CV 56%) steelhead trout and 4,593 (CV 34%) Chinook salmon returning adults. Variability in estimated fish numbers reflects application of densities and survival rates from other populations, assumptions about salmonid productivity in response to potential spawning habitat capacity, residency and outmigration of early life-stages, summertime water quality conditions, and inter-annual hydrograph, marine, and population variability.