Periodicity analysis of movement recursions.

Many animals adaptively use their environments by adjusting how long and how often they use specific areas of their home range. Whereas questions about residence times have been addressed for a long time, the study of movement recursions has only recently received due interest. A key question concerns the potential periodicity of such recursions, as many potential drivers of movement behaviour such as light, climate or plant-herbivore interactions can be periodic. We propose here to build upon well-established Fourier and wavelet analyses to extract periodic patterns from time-series of presence/absence, arrival or departure from areas of interest, and introduce reliable null models for assessing the statistical significance of the periods detected. We provide an illustrative example which shows how an impala (Aepyceros melampus) expressed periodic use of the main open area of its home range. The significant periods found (12 h using arrival times; 24h, 7 days, and 30 days using presence/absence records) were consistent with a use of this area linked to predation and disturbance, as the area was used more at night, closer to dark moon, and during week-days. Our approach is a further step towards building up a wider analytical framework for the study of movement ecology.