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The Fisher (Pekania pennanti) is a mesocarnivore of conservation concern in the Pacific coastal region of North America with a diverse but poorly understood diet. From 1995 to 2001, we collected 297 scats from 11 radio-collared females and 83 scats from 8 radio-collared males, and used frequency of occurrence (percentage of scats containing a particular food item) to investigate their diets. Mammals were the most frequently occurring food item in the diets of both female and male Fishers (84.8 and 77.1 % of scats, respectively); however, the prevalence of small (≤166 g) mammalian prey was relatively low (<13% of female and <9% of male scats). Medium (191–579 g) and large (643–1710 g) mammalian prey were 6.6 and 2 times more prevalent, respectively, in the diet of females compared to males, and very large prey (≥2085 g) were almost 26 times more prevalent in the diet of males. Female Fishers are about 50% smaller than males and may be less effective than males at capturing very large prey. However, in the diet of females raising kits, leporids (large prey) and ground squirrels (medium prey) were 3 and almost 2 times more prevalent, respectively, than they were among females with no kits. Focusing on such prey would provide more metabolic energy per capture than mice, voles, and other small mammals, and require fewer hunting forays away from kits. Thus, our findings show that sexual dimorphism and female reproductive condition influence the diet of Fishers in the Cascade Range of southern Oregon. Studies that use molecular techniques to identify food items in scats that were collected with a rigorous sampling design that enables researchers to link Fisher diets with correlates of fitness are needed to determine the extent to which food habits influence Fisher population dynamics in this region.
We describe activity patterns of North American River Otters (Lontra canadensis) in relation to social group size and the presence of young. Over the course of 15 y, we collected observations of 8 River Otter behaviors from a network of citizen scientists in northern California, retaining 1692 records following a rigorous data-cleaning process. Observers were asked to indicate 1 or more of the following 8 behaviors: “diving”, “swimming”, “walking”, “running”, “digging”, “turning rocks”, “pursued birds”, and “retreating from observer.” We treated “digging”, “turning rocks”, and “pursued birds” as alternative foraging strategies in some comparisons. Assessment of these reports showed that families were seen diving, running, and retreating from the observers more frequently than adult groups. Likewise, adult social groups behaved differently than solitary adult otters. Propensity to retreat from humans increased with increasing group size in social otters, whereas diving behavior also increased with group size. Solitary adults employed alternative foraging strategies more than adults in social groups. Citizen observers also reported that diving and styles of foraging behavior varied among months for adult otters. Taken together, these results provide evidence that citizen-science questionnaires can be used to provide insight into the natural behaviors of species that are difficult to observe.
The Porcupine (Erethizon dorsatum) is considered ‘secure' in British Columbia, but as for many species with this status, there is a notable absence of quantitative data on population trends. In view of this issue, concerns about declining numbers of the species prompted us to conduct a preliminary survey using a questionnaire in 2005, targeting various sectors of government, industry, and the public across British Columbia. Ten years later, we distributed a nearly identical questionnaire to allow comparisons and identify changes over the intervening decade. Respondents in both surveys reported a perceived decline in Porcupine sightings, although there was no significant change in the overall combined level of concern of respondents for the population between the 2 surveys; however, the proportion of respondents reporting that they were “very” concerned about the population trend over time did increase from the 2005 to 2015 survey. We augmented this information with data from road-mortality datasets collected by the provincial government and Parks Canada. Both datasets provided further support for a decrease in Porcupine abundance in the province. We discuss possible causes for this apparent decline, including natural population dynamics and the impact of climatic variation on predator-prey dyads. Overall, a comprehensive field study on Porcupine populations is needed to accurately assess the status of this species in British Columbia to corroborate our survey results suggesting a decline.
Human activities are influencing Earth's systems. Combine our effects with the natural dynamism of climate and ever-changing habitat structures and we have an important opportunity to quantify, evaluate, and predict how biodiversity responds to change. Birds react quickly to modifications in habitat availability and characteristics, so quantifying their distributions and abundances can be especially informative. Here, we provide an overview of our strategies and efforts to create an exactly repeatable benchmark of the distribution and abundance of birds in Oregon early in the twenty-first century. The effort was designed to provide future society with an opportunity to understand more clearly how birds respond to change by leaving a legacy of high-quality, accurately geo-referenced bird-count data. By implementing a simple, yet elegant, sampling design, involving more than a thousand citizen scientists and a few professional ornithologists, we established an unprecedented opportunity for before-after comparisons of population sizes and geographic distributions. Our approach offers future researchers the opportunity to replicate our work using exactly the same methods and look back with 20/20 hindsight to understand responses of birds to change over time and space. Hence, the project is named Oregon 20/20 Birds. Launched in 2011, the decade-long data-collection effort produced counts from more than 20,000 locations by professionals using methods that allow statistical adjustments for detectability and availability of birds, plus more than 50,000 locations where stationary counts were conducted at accurately georeferenced sites by professionals and citizen scientists. Here we summarize information on the project design, approaches for involving citizen scientists (birders using eBird), decision processes for selecting and comparing eBird data with professionally gathered data, and project goals. Results will be reported in future journal articles and books. In addition to providing legacy data for comparison with future repeat surveys, the project also provides a unique resource for addressing current questions in ecological, biogeographical, and evolutionary fields of study, as well issues involving conservation and management of Oregon's birds.
Stream-obligate amphibians are important indicators of ecosystem health in the Pacific Northwest, but distributional information to improve forest management is lacking in many regions. We analyzed archived DNA extracted from water samples in 60 pools in streams on private timberlands in Mendocino County, California, for 3 California Species of Special Concern—Coastal Tailed Frogs (Ascaphus truei), Foothill Yellow-legged Frogs (Rana boylii), and Southern Torrent Salamanders (Rhyacotriton variegatus)—to better understand their distributions in the region. Detection probabilities for eDNA of Foothill Yellow-legged Frogs and Coastal Tailed Frogs were positively influenced by water temperature. eDNA occurrence for both frogs was affected by whether silt or organic matter was a dominant substrate in the sampled pool, and Foothill Yellow-legged Frog eDNA occurrence was also affected by water temperature. Foothill Yellow-legged Frog eDNA occurrence had a strong, positive association with water temperature, with occurrence unlikely below 14°C and very likely above 16°C, and a positive association with silt or organic substrates in pools, which was likely an indicator of higher-order stream reaches. In contrast, Coastal Tailed Frogs had a negative association with silt or organic substrates. Historical visual detections were generally congruent with findings using eDNA, but differences highlight important areas for further study. We did not detect Southern Torrent Salamanders using eDNA at any sites. Our study reinforces that ecological relationships of these species are varied, and shows the importance of maintaining the integrity of streams with diverse characteristics for conserving stream amphibians.
To capture individuals in the field, small mammal researchers employ live-trapping, which can be influenced by trap type. Past studies of trap type on capture or recapture success revealed evidence of species- and habitat-specific biases. Therefore, to increase live-trapping success, we need more studies that examine effects of trap type on capture and recapture success of various species across different habitats. North American Deermice (Peromyscus maniculatus) are extensively used in ecological research, and, to our knowledge, no study has investigated trap type effects on Deermice in sagebrush habitat. Therefore, we examined the effects of trap type (Longworth and Sherman) on capture and recapture success of Deermice in sagebrush habitat of Montana during the summer season. We found that trap type did not influence capture or recapture success of any demographic class of Deermice. Therefore, Longworth and Sherman traps have similar capture and recapture success of Deermice, at least in sagebrush habitat during the summer. In conclusion, we recommend that researchers continue to examine how trap type may influence capture or recapture success so we can learn how to best maximize captures across species and habitats.
Brazilian Free-tailed Bats (Tadarida brasiliensis) had never been documented as breeding in southern Oregon. In 2017 and 2018, however, we report a natal colony of Brazilian Free-tailed Bats in southern Oregon, approximately 145 km west-northwest of the closest-known natal colony of this species, located in Lava Beds National Monument. The expansion of maternity sites may be the result of range expansion in response to warmer temperatures in the region owing to climate change and/or to adaptations to man-made structures for roosting.
The Calico Surfperch (Amphistichus koelzi) shares a similar size, morphology and feeding habitat with its 2 widely-sympatric congeners, the Barred Surfperch (Amphistichus argenteus) and Redtail Surfperch (Amphistichus rhodoterus). Like the other 2 species, A. koelzi is an important commercial and recreational resource, but unlike these species, A. koelzi has received virtually no attention in the scientific literature. We found average relative fecundity to be significantly higher than in A. koelzi's 2 congeners, A. argenteus and A. rhodoterus, and the slope of the regression of brood count on female size in A. koelzi was steeper and translated to the left of the same slopes representing the 2 congeners.
Intraspecific agnostic behavior is well-known in hummingbirds; however, lethality in North American species is unreported. Here we describe an observation of a lethal attack by a male Anna's Hummingbird (Calypte anna) on another male of the same species during mid-winter near the northern extent of the species' winter range.
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