A framework for modelling range shifts and migrations: asking when, whither, whether and will it return

摘要: Summary Many animals undertake movements that are longer scaled and more directed than their typical home ranging behaviour. These include seasonal migrations (e.g. between breeding feeding grounds), natal dispersal, nomadic range shifts responses to local environmental disruptions. While various heuristic tools exist for identifying migrations, none explicitly model the movement of within a statistical framework facilitates quantitative comparisons. We present mechanistic shift analysis (MRSA), method estimate suite parameters: times initiation, duration transitions, centroids areas respective ranges. The can take autocorrelation irregular sampling is characteristic much data into account. parameters suggest an intuitive measure, index, extent shift. likelihood based estimation further allows tests several relevant hypotheses, including test, stopover test site fidelity test. provided in R package (marcher). We applied MRSA population GPS tracked roe deer (Capreolus capreolus) Italian Alps 2005 2008. With respect migration, this extremely variable difficult classify. Using MRSA, we were able quantify behaviours across among individuals years, extents, durations locations shifts, cases would have been ambiguous detect using existing tools. The strongest patterns differences years: many simply did not perform migration wintering grounds during mild winter 2006–2007, even though some these same move extensively other, harsher winters. For migrants, however, years was high, after skipping entire migration. results behavioural plasticity tactical immediate cues reflected decision whether rather where migrate. also revealed trade-off probability migrating size range.