Movement parameters of ungulates and scale‐specific responses to the environment

Abstract

Summary1. Most studies of animal movements and habitat selection do not recognize empirically that different components of the environment are important to animals at different scales. Often, availability of habitats is defined at one or more arbitrary spatio-temporal scales, but use of those habitats is constrained to one scale. Identification of scalar movement is the first step in developing models to explain why animals select or move to certain parts of their range. We used a non-linear curve-fitting model of movement rates to identify discontinuities in the scales of movement by woodland caribou Rangifer tarandus caribou collared with global positioning system (GPS) collars. 2. We differentiated intrapatch from interpatch movements, but were unable to distinguish interpatch from migratory-type movements for most combinations of individual caribou by season. Model fit was stronger for winter than summer movements. We suggest that increased patch heterogeneity during the winter resulted in interseason variation in movements and corresponding model fit. 3.Responses by caribou to the environment were scale-dependent. When we applied logistic regressions, land-cover type, energetic costs of movement, and predation risk differentiated the two scales of movement. Intrapatch movements had a lower cost of movement, were associated with cover types where foraging behaviours probably occurred, and were closer to areas of higher predator risk than interpatch movements. 4. Application of the non-linear model will aid in developing mechanism-based approaches to studying resource selection and animal behaviour.

Range size and seasonal movement for female woodland caribou in the boreal forest of northeastern Ontario

“…Even so, many biotic and abiotic factors interact to influence an animals' spatial behaviour. The relative importance and interaction of variables such as land-cover type, energetic costs of move¬ ment, and predation risk may vary in relation to one another and the spatial scale at which animal move¬ ments are examined (Brashares & Arcese, 2002;Johnson et al, 2002).…”

“…Hastings (1990) indicated the importance of spatial factors in under¬ standing predator prey interactions. Range size and the tendency of an animal to return to the same range during consecutive years (fidelity) may reflect the pattern and scale at which factors limiting sur¬ vival (e.g., predation, forage, shelter) are influential (Rettie & Messier, 2001;Johnson et al, 2002). White & Garrott (1990: 121) defined migration as "a regular, round-trip movement of individuals between two or more areas or seasonal ranges."…”

Foraging theory upscaled: the behavioural ecology of herbivore movement

“…These authors noted that the 15 min interval was too coarse to reveal the true turning angles between feeding bouts. Johnson et al (2002) used a breakpoint in slope of the exponential distribution of movement 'steps' between GPS-based locations 3-4 h apart to distinguish intra-patch movements (presumably foraging) from inter-patch travelling for woodland caribou. At this temporal resolution, distinctions were diffuse and inconsistent among individuals.…”

Brownian motion or Lévy walk? Stepping towards an extended statistical mechanics for animal locomotion

“…This composite BM approach-from randomly mixing bouts of scale-specific movement at different scales-is feasibly described as intra-patch movement mixed with less frequent inter-patch movement [24,28]. Plank & Codling [29] extended Benhamou's [24] exemplification of Lévy look-alike processes from composite BM, by exploring a broader range of scale constants and conditions for the scale-specific components under a range of sampling lags on the generated series.…”