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Predicting Resource Effects on Animal Space Use with a Mechanistic Step-Selection Model

This study presents a mechanistic step-selection model developed to predict local and non-local effects of resource availability on animal space use. By incorporating the start and end points of animal steps, as well as step length and turning angle distributions, the model provides insights into how resource quality influences animal movement. Using Caribou data from Newfoundland, we quantify habitat selection across artificial landscapes. The model demonstrated significant changes in space-use patterns compared to traditional resource selection methods, revealing new dynamics in animal behavior associated with resource distribution.

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Predicting Resource Effects on Animal Space Use with a Mechanistic Step-Selection Model

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  1. Predicting local and non-local effects of resources on animal space use using a mechanistic step-selection model Jonathan Potts, Guillaume Bastille-Rousseau, Dennis Murray, James A. Schaefer, Mark Lewis. ESA2013, Minneapolis, 5 August 2013.

  2. From process to pattern

  3. From process to pattern Leave this out for today!

  4. Classical resource selection analysis Space use: Availability: Resource quality:

  5. Accounting for movement: the story so far • Moorcroft and Barnett (2008) Ecology, 89(4), 1112–1119

  6. Accounting for movement: the story so far • Moorcroft and Barnett (2008) Ecology, 89(4), 1112–1119 • Idea: Use the resource selection function for the movement kernel

  7. Accounting for movement: the story so far • Moorcroft and Barnett (2008) Ecology, 89(4), 1112–1119 • Idea: Use the movement distribution for the availability function • More precisely,

  8. Accounting for movement: the story so far • Moorcroft and Barnett (2008) Ecology, 89(4), 1112–1119 • Idea:Use the movement distribution for the availability function • More precisely, • = displacement distance distribution • = the selective value of habitat at

  9. Accounting for movement: the story so far • Moorcroft and Barnett (2008) Ecology, 89(4), 1112–1119 • Idea:Use the movement distribution for the availability function • More precisely, • = displacement distance distribution • = the selective value of habitat at • Gives a master equation for the animal probability density • Can use this to derive PDE of space use

  10. Accounting for movement: the story so far • Result: • i.e. the animal’s position distribution at a point is a function of the resource quality at that point

  11. Classical resource selection analysis Space use: Availability: Resource quality:

  12. Accounting for movement: the story so far • Result: • i.e. the animal’s position distribution at a point is a function of the resource quality at that point

  13. Problem: no effect of patch size and isolation Red = better resources Blue = worse resources

  14. Our model: weight based on start and end of step • Potts JR, Bastille-Rousseau G, Murray DL, Schaefer JA, Lewis MA. Predicting local and non-local effects of resources on animal space use using a mechanistic step-selection model. Methods in Ecology and Evolution(in review)

  15. Our model: weight based on start and end of step Step length and turning angle distributions • Potts JR, Bastille-Rousseau G, Murray DL, Schaefer JA, Lewis MA. Predicting local and non-local effects of resources on animal space use using a mechanistic step-selection model. Methods in Ecology and Evolution(in review)

  16. Our model: weight based on start and end of step Step length and turning angle distributions Relative quality of resources at x compared to those at y • Potts JR, Bastille-Rousseau G, Murray DL, Schaefer JA, Lewis MA. Predicting local and non-local effects of resources on animal space use using a mechanistic step-selection model. Methods in Ecology and Evolution(in review)

  17. Our model: weight based on start and end of step Step length and turning angle distributions Relative quality of resources at x compared to those at y • Potts JR, Bastille-Rousseau G, Murray DL, Schaefer JA, Lewis MA. Predicting local and non-local effects of resources on animal space use using a mechanistic step-selection model. Methods in Ecology and Evolution(in review)

  18. Our model: weight based on start and end of step Step length and turning angle distributions Relative quality of resources at x compared to those at y where is the intersection of with the half-line starting at and continuing on a bearing of .

  19. Parameterise the model using Caribou data from Newfoundland

  20. Weighting function W[H(x),H(y)] • According to this: Wetland > Barren > Coniferous open > Coniferous dense > Other

  21. Results: space use in artificial landscape Resources: Red = Wetland; Blue = Coniferous dense Animal space use distribution, assuming step lengths and turning angle distributions are the same for both habitats

  22. Results: patch size and isolation

  23. Acknowledgements Mark Lewis (University of Alberta) Guillaume Bastille-Rousseau (Trent University) Dennis Murray (Trent) James Schaefer (Trent) Members of the Lewis Lab (Alberta)

  24. Conclusions • Our simple change to the step selection function causes dramatic changes in the space use distribution • Predicts aspects of space use that standard resource selection methods do not

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