Annual movement strategy predicts within-season space use by moose

Tomasz Borowik,Norbert Duda,Rafał Kowalczyk,Weronika Maślanko,Mirosław Ratkiewicz

doi:10.1007/s00265-021-03059-4

Abstract

The heterogeneity of resource availability shapes animal movements at different spatio-temporal scales. Given that movements at various scales are assumed to be linked, the space use of temperate ungulates within seasonal ranges (winter, summer) should be related to their movement patterns at the annual scale. In this study, we aimed to evaluate the level of stationarity of moose (Alces alces) within their seasonal ranges and to link annual movement patterns to within-season space use. We analysed the ranging behaviour of 32 moose fitted with GPS collars from two study areas in Eastern Poland, where at the annual scale a fraction of individuals migrate between summer and winter ranges (partial migration). Our results revealed that moose stationarity within seasonal home ranges expressed remarkable variation. The probability of moose stationarity within seasonal ranges was significantly higher (by 23%), and the mean home range size tended to be lower (9.7 km2) among individuals that seasonally migrated than among non-migratory moose (14.3 km2). In addition, we found that (i) in summer, moose were significantly more stationary (by 19%) and exhibited a smaller mean home range size than in winter (9.0 and 15.9 km2, respectively) and (ii) the mean seasonal home range size of males (19.6 km2) was remarkably greater than that of females (9.6 km2). Given the significant link between annual and seasonal scales of animal movements, any environmental change (e.g. climate warming) affecting an animal’s annual movement strategy could alter within-season animal space use and presumably individual fitness.Significance statementTo maximize their fitness, animals adjust their movements to deal with variations in resource distribution in the landscape. The scale of spatio-temporal variation causes different types of migratory behaviours, ranging from year-round stationarity to migration, when individuals establish spatially separated seasonal ranges. Studies on ungulates suggest that the stability and the size of seasonal home ranges can be linked to annual movement behaviour. Using the locations of GPS-tracked moose, we demonstrate in this study that migratory individuals were more prone to establishing stable seasonal home ranges (especially in summer) than moose that occupied the same area throughout the year. Moreover, stable seasonal home ranges were remarkably smaller in summer than in winter, which may suggest a season-specific spatial distribution and a renewability of moose forage. Our results show a clear link between different temporal scales of animal movements.

Highlights

Animal movement is driven by an individual’s intrinsic motivation to move, its ability to move as well as a broad set of extrinsic factors (Nathan et al 2008)
Using the locations of GPS-tracked moose, we demonstrate in this study that migratory individuals were more prone to establishing stable seasonal home ranges than moose that occupied the same area throughout the year
0.440 0.386 0.097 0.076 < 0.001 < 0.001 < 0.001 < 0.001 movement strategy (P = 0.09): individuals with spatially separated seasonal home ranges had smaller seasonal home ranges than non-migratory moose (9.7 and 14.3 km2, respectively) (Figs. 4 and 6)

Summary

Introduction

Animal movement is driven by an individual’s intrinsic motivation to move, its ability to move as well as a broad set of extrinsic factors (Nathan et al 2008). Animals are expected to leave specific patch when the energetic benefit of foraging in it drops below the average value of other available patches. For a given data series, animal movements can be classified as stationary at a specific temporal scale, but at finer scales a mixture of stationary and non-stationary periods can be observed (multiphasic movements). An animal’s movement can be considered stationary at the seasonal scale, while at finer scales, the seasonal tracking period can be divided into several stationary and non-stationary phases (Johnson et al 2002; Börger et al 2008; Benhamou 2014; Couriot et al 2018)

Objectives

Methods

Results

Conclusion