Ecological Archives A022-060-A1
Nicholas J. DeCesare, Mark Hebblewhite, Fiona Schmiegelow, David Hervieux, Gregory J. McDermid, Lalenia Neufeld, Mark Bradley, Jesse Whittington, Kirby G. Smith, Luigi E. Morgantini, Matthew Wheatley, and Marco Musiani. 2012. Transcending scale dependence in identifying habitat with resource selection functions. Ecological Applications 22:1068–1083.
Appendix A. Defining seasons according to migration parameters.
Woodland caribou within our study area are partially migratory (McDevitt et al. 2009), and we based seasonal distinctions in resource selection on the timing of migration events between winter and summer use areas. We used methods of Bunnefeld et al. (2011) to quantify parameters of migration including the midpoint dates of spring and autumn migration for a set of 32 migratory individuals across the study area. These methods fit nonlinear regression models to the net-squared displacement of daily locations per Julian day and estimated migration midpoint dates (
ij) for each individual i and season j (Bunnefeld et al. 2011). We fit their migration model (eq. 1, p. 469; Bunnefeld et al. 2011) to estimate migration midpoint dates for each individuals and estimated inverse variance weighted population-averaged mean migration midpoint dates (
j) across individual estimates (Murtuagh 2007) as:
 | (A.1) |
where wij = seasonal individual parameter weights estimated as:
 | (A.2) |
According to our sample of migratory caribou, the estimated midpoints of spring and fall migrations were 16 May and 17 October, respectively (Fig. A1). Thus we modeled resource selection of all caribou individuals and populations according to summer (16 May–16 October) and winter (17 October–15 May) seasons delineated by quantitative analysis of migration movements.
Fig. A1. Nonlinear models of net-squared displacement (km2) of daily GPS telemetry locations by Julian day for 32 migratory female woodland caribou in west-central Alberta and eastern British Columbia, 1998–2009.
Literature Cited
Bunnefeld, N., L. Börger, B. van Moorter, C. M. Rolandsen, H. Dettki, E. J. Solberg, and G. Ericsson. 2011. A model-driven approach to quantify migration patterns: individual, regional and yearly differences. Journal of Animal Ecology 80:466–476.
McDevitt, A. D., S. Mariani, M. Hebblewhite, N. J. DeCesare, L. Morgantini, D. Seip, B. V. Weckworth, and M. Musiani. 2009. Survival in the Rockies of an endangered hybrid swarm from diverged caribou (Rangifer tarandus) lineages. Molecular Ecology 18:665–679.