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Climatically sensitive species are naturally expected to experience disproportionate impacts from climate change. Although many vertebrates select microhabitats that allow them to persist toward the edge of their physiological limits, climate-driven models are often conducted at spatial scales too coarse to capture these fine-scale behaviors. One such climatically limited species is the monotypic Mountain Beaver (Aplodontia rufa), a species endemic to western North America. Mountain Beavers have physiological constraints that limit their distribution to cool, moist habitats. Although they have persisted through past periods of climate change, increasing temperature since the last glacial maximum is believed to have had a strong influence in reducing their range. This is particularly true for the federally endangered Point Arena subspecies of Mountain Beaver (Aplodontia rufa nigra; hereafter PAMB), found toward the southwestern edge of their range in Mendocino County on the coast of California. Previous efforts to model PAMB habitat suitability were conducted at the landscape scale. However, as a climatically sensitive taxon with limited mobility, it is important to understand the influence of microclimates on habitat suitability, particularly in the context of global climate change. We created downscaled climate data that we combined with known locations of PAMB to create a fine-scale species distribution model. Mean temperature was the strongest predictor of PAMB presence, with an increased probability of presence at lower mean temperatures. Although PAMB may be living at the edge of their physiological limits, they appear to be selecting habitat at a microclimate scale similar to elsewhere in their range, which allows them to persist at this margin. Conservation efforts for PAMB should prioritize habitat restoration, as well as maintaining and increasing connectivity between microrefugia, to provide cooler areas for PAMB persistence.
In 2012, we explored the activity pattern of a pair of breeding Northern Pygmy-Owls based on 15 d (and 15 nights) of video monitoring of the nest-cavity entrance during the nestling period. Video monitoring ended after all 6 owlets had left the nest. All instances of nest activity (n= 288) occurred during the daylight period from 1 h before sunrise to 1 h after sunset, so the pair was not nocturnal. Most of the activity (60%) occurred during the diurnal period (1 h after sunrise to 1 h before sunset), and the rest was in the crepuscular period (the first and last 2 h of daylight). Prey type factored heavily into the frequency of activity at certain times of day, and on certain days during the nestling period. Activity during the diurnal period was dominated by the combination of vertebrate prey deliveries (80% of diurnal activity) and enticements of young from the nest (14% of diurnal activity). In contrast, activity during the crepuscular period was dominated by insect prey deliveries (60% of crepuscular activity). Overnight nest attendance activity, arriving and departing the nest to tend young through the night, accounted for 11% of crepuscular activity. For the entire 15-d monitoring period, deliveries of vertebrate prey made up 60% of all activity. The frequency of daily vertebrate prey deliveries was relatively similar for the first 10 full days of monitoring (range 9 to 13 deliveries), then peaked 3 to 4 d prior to fledging (range 15 to 20 deliveries) before declining on the last 2 d of the period, when deliveries of moths and enticement activity increased. We concluded that the pair's activity during the nestling period was consistent with a diurnal activity pattern. We encourage other researchers to refine the meanings of the terms diurnal and crepuscular and clarify how those terms should be used to define the primary activity pattern of a species.
In this exploratory study, we investigated amphibian movement across a new 1.4-km residential road system adjacent to a wetland complex in Thurston County, Washington. We implemented this study prior to home construction, and before traffic levels associated with occupancy occurred. Our purpose was to document pond-breeding amphibian movement patterns to identify safe-crossing recommendations. One 24-h walking survey was conducted per month from October to December 2008, and in February 2009. We observed 7 native amphibian species and tallied 225 amphibian observations. The data showed differences in autumn to winter migration timing and direction relative to the wetland complex among species, sexes, and life stages. Most adults were moving toward the wetlands, whereas most juveniles were moving away. The highest number of observations occurred during the 00:00 to 03:59 h dark interval, corresponding with lowest local traffic volume. Nearly all observations for Northern Red-legged Frog (Rana aurora), Pacific Treefrog (Hyliola regilla), Long-toed Salamander (Ambystoma macrodactylum), and Northwestern Salamander (Ambystoma gracile) occurred after dark. However, Rough-skinned Newt (Taricha granulosa) peak movement occurred during daylight, corresponding with the highest traffic volume. We documented diffuse movement throughout the road system. Spatial analyses highlighted 2 significant crossing hot spots, including a 1.8-m diameter culvert. This study illustrates the importance of understanding the spatial and temporal patterns in pond-breeding amphibian migrations to effectively plan and implement measures to reduce amphibian road mortality. Prior to new development, we encourage proactive planning, such as connectivity, traffic, and traffic calming analyses to identify amphibian migration locations and reduce mortality. In areas with existing roads, such as the study site, we suggest implementation of mitigation measures paired with effectiveness monitoring.
Survival estimation is critical to studies of wildlife population biology, and recent model developments allow for temporal covariates on mortality risk. To test model assumptions that scavengers do not influence either perceived mortality cause or location, we randomly placed 24 radio-marked Chukar (Alectoris chukar) carcasses over gradients of grassland habitat conditions in eastern Montana in both April 2017 and July 2018, and monitored scavenging activity at intervals relevant to gamebird telemetry studies. High rates of scavenging (12.5–78%, depending on season and relocation interval) suggest that scavenging activity could confound determination of cause-specific mortality, but that its influence varies with season. Scavenging activity did not significantly influence perceived mortality locations regardless of season or local habitat conditions with a relocation interval of 3 d (8% of carcasses moved), but mortality locations may be biased over longer periods (50% of carcasses moved in 7-d period), particularly in warm seasons or regions.
We document the 1st record in 93 y of Umpqua Chub (Oregonichthys kalawatseti) in the North Umpqua River. Although the North Umpqua River has been surveyed for Umpqua Chub over the past 3 decades without success, we captured 34 Umpqua Chub on 14 May 2019, using baited minnow traps, 5.8 km downstream from Winchester Dam on the North Umpqua River. We vouchered 1 specimen for confirmation of field identification at the Oregon State University Ichthyology Collection (OSUIC). Our unexpected capture of Umpqua Chub in the North Umpqua River supports an almost century-old record of the species presence in the river and marks a significant extension of its known range in the Umpqua River basin.
Apex carnivores, including Pumas (Puma concolor), play a key role in ecological communities. Pumas have variable foraging patterns across their extensive range and are known scavengers. A recent review of Puma diet and predation studies documented a total of 48 mammal prey types representing 9 of the 13 orders found in North America, but excluding marine mammals (Orders Cetacea and Sirenia, and Clade Pinnipedimorpha) or tapirs (Order Perissodactyla). This report documents what is, to the best of our knowledge, the 1st observation of a Puma feeding on a marine mammal, a Harbor Seal (Phoca vitulina). Pinnipeds, as hunted or scavenged prey, could be a significant resource for Pumas in coastal areas and should be a focus of future studies. Novel observations of prey items, such as this, are important to document as they expand our understanding of apex carnivores and the effects they have on ecological communities.
Townsend's Solitaire (Myadestes townsendi) can carry significant quantities of food items in its oral cavity, pharynx, or esophagus, but the internal anatomy enabling this behavior and its phenological details have not been described. Here I report on the presence of a sublingual pouch formed by an enlargement of the mucous membrane (epithelium) of the floor of the mouth in both sexes of breeding birds, which is absent in juveniles and non-breeding adults. The free tongue (in particular the paraglossum) appears to be used to remove food from, and perhaps to sweep food into, the sublingual pouch. Development of a food-carrying pouch is probably an adaptation related to provisioning of the mate and young.