Avian scavengers perform a critical ecosystem service by breaking down dead and decomposing organic matter and recycling nutrients. However, the scavenging dynamics of birds have received relatively little attention compared to the dynamics of scavenging mammals. Carcasses provide an ephemeral food source for avian scavengers, which presents them with the unique challenge of locating the carrion. This makes detection and consumption efficiency a topic of interest as not all avian scavengers follow the same pattern of arrival at a carcass. Here, we examine avian scavenger succession – the order in which species arrive and consume carcasses – through monitoring ungulate carcasses in Washington State. We found that turkey vultures outcompeted all other avian scavengers when they were present in summer months, while black-billed magpies and common ravens outcompeted golden and bald eagles in winter months. This confirms previous studies that have found that turkey vultures have morphological and genetic advantages that enable them to readily find carcasses and that body size does not determine succession in this scavenging guild. Our study highlights how social scavengers outcompete solitary scavengers and reach carcasses sooner, regardless of the physical characteristics of a species.

In long term data collection, sampling is a key parameter that can dictate the amount of data collected and also influence the available conclusions to be drawn. In the context of passive acoustic monitoring, recording an area’s soundscape at intervals (i.e., subsampling based on duty cycles) can alleviate data management costs, and has been widely investigated in the bird monitoring literature. However, the influence of duty cycle-based subsampling in passive acoustic monitoring of bats has not been thoroughly studied. Here, we discuss the effects of subsampling on ultrasonic recordings collected using AudioMoth recorders in the Union Bay Natural Area in 2022. We recorded continuously over the summer and then computationally applied duty cycles onto our data to generate subsampled data. The subsampled data was then fed into multiple bat call detection algorithms to understand the influence of different subsampling schemes. Our results show that subsampling schemes can impact the trends and activities that can be acoustically observed from echolocating bats. The results also show how the subsampling parameters may be tuned to collect valuable information while keeping data management costs low. We anticipate that this detailed investigation will aid in the design of efficient, long-term bat acoustic monitoring projects.

The marine intertidal is subject to challenging hydrodynamic forces. Organisms that reside within these zones; such as purple (Strongylocentrotus purpuratus) and green (Strongylocentrotus droebachiensis) sea urchins, must have strong attachment to prevent dislodgement, ambulate, and feed in intense environmental conditions. Sea urchins attach to the substrate via their podia (tube feet). The disc found in the distal part of tube feet has a duo-gland that releases specialized adhesive compounds and de-adhesive enzymes to achieve adhesion. Adhesive performance was evaluated to determine if purple sea urchins, that are predominantly found in high wave exposure areas, have better adhesive performance than green sea urchins, which are abundantly found in areas protected from wave action. We evaluated the following adhesive performance variables: stem mechanical properties, tube foot disc tenacity, attachment area, speed of detachment and whole animal adhesive force. We found that for most adhesive performance metrics, purple urchins performed better than greens, except for detachment speed. These results suggest that, in the field, behavioral changes may play an important role in determining risk of detachment for sea urchins. Understanding how morphology, behavior and mechanical properties of tube feet work in conjunction to provide strong attachment, is critical to predict sea urchin fitness in challenging environmental conditions.

 The diversification of many vertebrate groups was spurred by the use of novel food resources, and jaw functional morphology provides clues about the adaptations associated with dietary diversification. The external dimensions along the mandible reflect strength to resist bite forces, which are in turn associated with physical properties of the diet. Variation in these dimensions along the jaw and between different species therefore may reflect adaptations of the jaw to specific diets. We applied this biomechanical framework to investigate the relationship between jaw robustness and diverse diet types in bats. Using mandibles of more than 60 species, we quantified the external dimensions at interdental gaps to generate mandibular strength profiles. The strength profiles of frugivorous, insectivorous, and omnivorous bats showed similar patterns, with a trend of increasing jaw depth toward posterior teeth. All diet types showed a high level of variation in jaw shape along the toothrow, suggesting differences in the functional roles of different teeth. Insectivores showed the greatest within-guild variation in jaw shape, while nectarivores had noticeably gracile symphyses. Further, insectivorous bats showed relatively deep jaws at the canine and premolars, which may be associated with the use for prey capture, while frugivores have relatively deep jaws at the posterior molars, possibly linked to adaptations for crushing seeds and pulp. These results suggest that mandible strength profiles reflect dietary adaptations in bats.

Currently, two of the biggest threats to the survival of Pacific Northwest bat populations are climate change and habitat loss. The Union Bay Natural Area (UBNA) is an ecological conservation site and important urban green space that provides a critical habitat for a variety of wildlife, including bats. In 2022, this region experienced its hottest summer on record, however little is known about the effects of extreme heat on the bat community in this area. Here we investigate the potential impact of temperature and air quality on bat activity in UBNA using passive acoustic monitoring data collected over a period of six months, from July to December 2022. We hypothesized that bat activity patterns are altered during extreme weather events. We used a Band-Limited Energy Detector (RavenPro) to detect the presence of bat calls in the recording and represent the bat occurrences in the form of an activity grid. The acoustic detections are contextualized using data from nearby weather stations reporting temperature and air quality indexes. Our results contribute to understanding the impacts of environmental factors on bat populations and can help guide further conservation efforts in UBNA.

Large predators are particularly sensitive to human disturbance due to their slower life histories, large home ranges, and persecution by humans. Previous research shows that top predators have the ability to alter trophic relationships from their positions at the top of food webs. Therefore, anthropogenic-mediated behavioral changes in large predators could exert indirect and direct impacts on the entire ecological community. In Washington, cougars (Puma concolor) inhabit landscapes with increasing human disturbance, making this state an ideal place in which to explore how anthropogenic activity shapes their behavior. In this study, we examined cougar feeding behaviors in response to road, trail, and building density. We used camera traps deployed at fifty-five cougar kill sites to detect carcass visitation, and GPS collars on cougars to assess the total time spent at a carcass. A hurdle model was used to predict the probability of observing a cougar on a camera trap in relation to road, trail, and building density. Cougars were found to spend significantly less time feeding in areas of higher road density (p < 0.001) and building density (p < 0.001). This indicates that human infrastructure (proxied by road density) and human presence (proxied by building density) reduce cougar feeding opportunities. Our study shows that as the human footprint continues to expand into cougar habitats, cougars may experience further disruptions to their feeding dynamics. Understanding the behavioral response of large predators to disturbance is critical in the management of intact ecosystems and in mitigating human-wildlife conflict.