Current Projects
Wolf freshwater fishing behavior
Through global positioning system (GPS) collar locations, remote cameras, field observations and the first wild wolf to be GPS-collared with a camera collar, we describe when, where and how wolves fish in a freshwater ecosystem. From 2017 to 2021, we recorded more than 10 wolves (Canis lupus) hunting fish during the spring spawning season in northern Minnesota, USA. Wolves ambushed fish in creeks at night when spawning fish were abundant, available and vulnerable in shallow waters. We observed wolves specifically targeting sections of rivers below beaver (Castor canadensis) dams, suggesting that beavers may indirectly facilitate wolf fishing behaviour. Wolves also cached fish on shorelines. We documented these findings across five different social groups at four distinct waterways, suggesting that wolf fishing behaviour may be widespread in similar ecosystems but has probably remained difficult to study given its annual brevity. Spawning fish may serve as a valuable pulsed resource for packs because the spring spawning season coincides with low primary prey (deer Odocoileus virginianus) availability and abundance, and when packs have higher energetic demands owing to newly born pups. We demonstrate the flexibility and adaptability of wolf hunting and foraging behaviour, and provide insight into how wolves can survive in a myriad of ecosystems.
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Collaborators: Dr. Thomas D. Gable, Sean M. Johnson-Bice, Austin T. Homkes, Dr. Steve K. Windels and Dr. Joseph K. Bump
Beaver stress response to wolf predation
Beavers are ecosystem engineers that can modify habitats, resulting in landscape alteration that persists for centuries. By killing these engineers, predators such as wolves can alter the ecological processes that result from engineering, producing long-term landscape effects. If the risk of wolf predation results in chronic stress for beavers, the presence of wolves alone may have cumulative landscape impacts. Analysis of plasma, a widely used method to measure hormones, reflects short term stress and methods to obtain samples, and can be detrimental to subjects. In contrast, hair is a stable medium that stores a record of blood-borne molecules, can remain detectable for years, and requires less invasive collection methods. Hair snares have been successfully used in DNA analysis due to their ease to deploy, minimal disturbance, and the stability of storing samples - but such methods have yet to be widely applied to hormone analysis. We will investigate the hormonal implications of long term exposure to wolf predation on beaver colonies using hair snares. We will 1) analyze hair glucocorticoid levels from captive beavers to establish a baseline measure - something that to our knowledge has not been attempted for beavers, and 2) compare hair cortisol levels between wild beavers (in wolf presence) and captive beavers (in wolf absence). Our findings will provide insight for wildlife management, and be at the forefront for non-invasive sampling methods.
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Collaborators: Dr. Thomas D. Gable, Austin T. Homkes, Dr. Jennifer E. Smith, Dr. Ben Dantzer, Dr. Steve K. Windels, and Dr. Joseph K. Bump
