From migration to nomadism: movement variability in a northern ungulate across its latitudinal range

Abstract

Understanding the causes and consequences of animal movements is of fundamental biological interest because any alteration in movement can have direct and indirect effects on ecosystem structure and function. It is also crucial for assisting spatial wildlife management under variable environmental change scenarios. Recent research has highlighted the need of quantifying individual variability in movement behavior and how it is generated by interactions between individual requirements and environmental conditions, to understand the emergence of population-level patterns. Using a multi-annual movement data set of 213 individual moose (Alces alces) across a latitudinal gradient (from 56 degrees to 67 degrees N) that spans over 1100 km of varying environmental conditions, we analyze the differences in individual and population-level movements. We tested the effect of climate, risk, and human presence in the landscape on moose movements. The variation in these factors explained the existence of multiple movements (migration, nomadism, dispersal, sedentary) among individuals and seven populations. Population differences were primarily related to latitudinal variation in snow depth and road density. Individuals showed both fixed and flexible behaviors across years, and were less likely to migrate with age in interaction with snow and roads. For the predominant movement strategy, migration, the distance, timing, and duration at all latitudes varied between years. Males traveled longer distances and began migrating later in spring than females. Our study provides strong quantitative evidence for the dynamics of animal movements in response to changes in environmental conditions along with varying risk from human influence across the landscape. For moose, given its wide distributional range, changes in the distribution and migratory behavior are expected under future warming scenarios.

Diverse rates of gene flow and long-distance migration in two moose Alces alces subpopulations in Europe

“…Migration was defined as a seasonal movement with a return to the place of departure. Analysis of moose populations in Sweden showed a clear latitudinal pattern to their migratory behaviour (Singh et al 2012). The share of seasonal migrants in a population declined from 95 % in northern declined from 103 to 5 km, respectively.…”

“…Some species, such as moose Alces alces, also show high intraspecific variation in dispersal and migratory behaviour. Movement patterns of moose can vary between years and seasons and with the environmental conditions in the areas which they occupy (Singh et al 2012). It has been observed that some moose are able to migrate up to 800 km in Eurasia (Rozhkov et al 2009) and even over 1500 km in North America (Hoffman et al 2006).…”

“…It has been observed that some moose are able to migrate up to 800 km in Eurasia (Rozhkov et al 2009) and even over 1500 km in North America (Hoffman et al 2006). However, seasonal migrations are shorter: between 100 and 300 km in Russia (Filonov 1983), up to about 100 km in Scandinavia (Singh et al 2012) and between 65 and 179 km in North America (Filonov 1983 and references therein). Singh et al (2012) classified the movement behaviour of moose into different categories: migration, dispersal, nomadism and residence.…”

“…However, seasonal migrations are shorter: between 100 and 300 km in Russia (Filonov 1983), up to about 100 km in Scandinavia (Singh et al 2012) and between 65 and 179 km in North America (Filonov 1983 and references therein). Singh et al (2012) classified the movement behaviour of moose into different categories: migration, dispersal, nomadism and residence. Migration was defined as a seasonal movement with a return to the place of departure.…”

Asynchronous vegetation phenology enhances winter body condition of a large mobile herbivore

“…For large-bodied herbivores, the phenology of vegetation is a critical determinant of diet quality (Van Soest 1982, Crawley 1983) that has been linked to diet choice, individual movement and performance (Hjeljord et al 1990, Albon andLangvatn 1992;Herfindal et al 2006;Hebblewhite et al 2008;Mysterud et al 2008;Hamel et al 2009;Martinez-Jauregui et al 2009;Bischof et al 2012;Nielsen et al 2012;Singh et al 2012;Giroux et al 2014, as well as population processes such as survival, reproduction and density-dependence Wang et al 2006;Pettorelli et al 2007;Wittemyer et al 2007. The ability of landscapes to support herbivores is ultimately limited by the total amount of aboveground net-primary production (ANPP) available for consumption (McNaughton et al 1989;Cebrian and Lartigue 2004).…”