Effects of Novel Predators on Naive Prey
The most important effects of climate change on wildlife are thought to come from altered biological interactions. In the Arctic, one novel relationship that is emerging is the intrusion of polar bears into bird breeding colonies. As sea ice melts earlier in the year, polar bears find themselves combing ashore earlier, where they now overlap with the incubation period of Arctic breeding birds. While much work has been done on the potential energetic benefit of these eggs to bears, I am seeking to understand how nesting birds respond to predator systems in which birds have restricted evolutionary experience. To do this, I make use of field observations of polar bears foraging on bird nests (primarily Common eiders), and use these observations to build predictive simulation models of how birds should react to this novel source of predation.
Common Eider Responses To Foraging Polar Bears
Common eiders have one of the highest rates of nest attendance of all birds, they hardly ever leave the nest. But remaining with the nest in the face of a hungry polar bear may be dangerous, since a bear can easily kill an eider. Since time away from the nest is not good for incubating eiders, being able to judge the risk posed by polar bears is important for these birds in decided whether to leave the nest or not. To understand this problem, we are estimating the Flush Initiation Distance (FID) of eiders in response to foraging bears using drone video. We are hoping to understand the characteristics of bears that influence the eider's decision to leave the nest, and how small or large FIDs impact nest success.
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A female Common eider on her nest
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Simulation Modelling of Novel Predators on Naive Prey
Example simulation of a large mammalian predator moving through a nesting bird colony, which has been evolved to cope only with flying avian predators.
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Agent Based Models are a powerful method of understanding the role of individual behaviour on shaping population level responses. However, when you combine Agent Based Models with Artificial Neural Networks, simulations can incorporate the ability of individuals to learn and pass on their strategies to the next generation. In this way, we can "evolve" prey populations under various predator scenarios, and examine how they react to changes in predator populations.
Conceptually these models are run in two steps. First we allow birds to evolve under one type of predator environment, allowing them to "tune" their responses to a typical predator. Second, we introduce a new type of predator, and examine the impact that this new predator has on bird's nest success. |
Relevant Publications
Barnas, A.F., Geldart, E.A., Love, O., Jagielski, P.M., Harris, C., Gilchrist, G., Hennin, H.L., Richardson, E.S., Dey, C.J., and C.A.D. Semeniuk. 2022. Predatory cue use in flush responses of a colonial nesting seabird during polar bear foraging. Animal Behaviour. 193: 75-90 www.sciencedirect.com/science/article/abs/pii/S0003347222002329
Barnas, A.F., Darby, B.J., Iles, D.T., Koons, D.N., Rockwell, R.F., Semeniuk, C.A.D., and S.N. Ellis-Felege. 2022. Bear Presence attracts avian predators but does not impact lesser snow goose nest attendance. Journal of Avian Biology. 2022: e02840 onlinelibrary.wiley.com/doi/full/10.1111/jav.02840
Barnas, A.F., Iles, D.T., Stechmann, T.J., Wampole, E.M., Koons, D.N., Rockwell, R.F., and S.N. Ellis-Felege. 2020. A phenological comparison of grizzly (Ursus arctos) and polar bears (Ursus maritimus) as waterfowl nest predators in Wapusk National Park. Polar Biology. 43: 457-465 https://link.springer.com/article/10.1007/s00300-020-02647-w
Gormezano, L.J., Ellis-Felege, S., Iles, D.T., Barnas, A.F., and R.F. Rockwell. 2017. Polar bear foraging behavior during the ice-free period in western Hudson Bay: observations, origins, and potential significance. American Museum Novitates. 3885: 1-28 https://doi.org/10.1206/3885.1
Barnas, A.F., Darby, B.J., Iles, D.T., Koons, D.N., Rockwell, R.F., Semeniuk, C.A.D., and S.N. Ellis-Felege. 2022. Bear Presence attracts avian predators but does not impact lesser snow goose nest attendance. Journal of Avian Biology. 2022: e02840 onlinelibrary.wiley.com/doi/full/10.1111/jav.02840
Barnas, A.F., Iles, D.T., Stechmann, T.J., Wampole, E.M., Koons, D.N., Rockwell, R.F., and S.N. Ellis-Felege. 2020. A phenological comparison of grizzly (Ursus arctos) and polar bears (Ursus maritimus) as waterfowl nest predators in Wapusk National Park. Polar Biology. 43: 457-465 https://link.springer.com/article/10.1007/s00300-020-02647-w
Gormezano, L.J., Ellis-Felege, S., Iles, D.T., Barnas, A.F., and R.F. Rockwell. 2017. Polar bear foraging behavior during the ice-free period in western Hudson Bay: observations, origins, and potential significance. American Museum Novitates. 3885: 1-28 https://doi.org/10.1206/3885.1