Publications

Eurasian zebra and quagga mussels were likely introduced to the Laurentian Great Lakes via ballast water release in the 1980s, and their range has since expanded across the US, including some of their southernmost occurrences in Texas. Their spread into the state has resulted in a need to revise previous delimitations of suitable dreissenid habitat. We therefore assessed invasion risk in...

Assessments of climate-change effects on ecosystem processes and services in high-latitude regions are hindered by a lack of decision-support tools capable of forecasting possible future landscapes. We describe a collaborative effort to develop and apply the Integrated Ecosystem Model (IEM) for Alaska and northwestern Canada to explore how climate change influences interactions among...

Assessing trends in abundance and density of species of conservation concern is vital to inform conservation and management strategies. The remaining population of the cheetah (Acinonyx jubatus) largely exists outside of protected areas, where they are often in conflict with humans. Despite this, the population status and dynamics of cheetah outside of protected areas have received...

Thermal heterogeneity provides options for organisms during extreme temperatures that can contribute to their fitness. Sagebrush (Artemisia spp.) communities exhibit vegetation heterogeneity that creates thermal variation at fine spatial scales. However, fire can change vegetation and thereby variation within the thermal environment of sagebrush communities. To describe spatial and...

Avian research may require investigators to capture birds for many reasons, including to collect measurements and attach leg bands or transmitters. The effectiveness and efficiency of capture techniques varies by species, habitat, and time of year. Rails are particularly challenging to capture because of their secretive behavior and the dense vegetation they inhabit. As such, basic...

Territorial behavior is a fundamental and conspicuous behavior within numerous species, but the mechanisms driving territory selection remain uncertain. Theory and empirical precedent indicate that many animals select territories economically to satisfy resource requirements for survival and reproduction, based on benefits of food resources and costs of competition and travel. Costs of...

Ecological studies strive to identify factors that explain patterns of species distribution and abundance. In lizards, competition and predation are major forces influencing distribution and abundance, but there is also increasing evidence pointing at the influence of habitat structure and prey abundance. Our work explored the latter further by quantifying the effects of vegetation and...

Although most countries banned manufacturing of polychlorinated biphenyls (PCBs) over 40 years ago, PCBs remain a global concern for wildlife and human health due to high bioaccumulation and biopersistance. PCB uptake mechanisms have been well studied in many taxa; however, less is known about depuration rates and how post-exposure diet can influence PCB concentrations and immune...

Cisco (Coregonus artedi) and lake whitefish (Coregonus clupeaformis) are native fish species of management concern in the Laurentian Great Lakes that often overlap in spawning locations and timing. Thus, species-level inference from in situ sampling requires methods to differentiate their eggs. Genetic barcoding and hatching eggs to visually identify larvae are used but can be time and...

Acting Chief’s Message Dear Cooperators: Members of the Cooperative Research Units are pleased to provide you with the “2019 Year in Review” report for the Cooperative Fish and Wildlife Research Units (CRUs). You will first note that this report looks a little different than those published in the past few years, as we opted for a shorter, more concise format this year. Inside you will...

Acting Chief’s Message Dear friends, I invite you to take a look at U.S. Geological Survey Circular 1463, “Cooperative Fish and Wildlife Research Units Program—2019 Year in Review,” now available at https://doi.org/10.3133/cir1463. In this report, you will find details about the Cooperative Fish and Wildlife Research Units (CRU) program concerning fish and wildlife science, students...

Hellbenders Cryptobranchus alleganiensis are critically imperiled amphibians throughout the eastern USA. Rock-lifting is widely used to monitor hellbenders but can severely disturb habitat. We asked whether artificial shelter occupancy (the proportion of occupied shelters in an array) would function as a proxy for hellbender abundance and thereby serve as a viable alternative to rock...