Changing motivations during migration: linking movement speed to reproductive status in a migratory large mammal (original) (raw)
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Biology Letters, 2014
A challenge in animal ecology is to link animal movement to demography. In general, reproducing and non-reproducing animals may show different movement patterns. Dramatic changes in reproductive status, such as the loss of an offspring during the course of migration, might also affect movement. Studies linking movement speed to reproductive status require individual monitoring of life history events and hence are rare. Here we link movement data from 98 GPS-collared female moose (Alces alces) to field observations of reproductive status and calf survival. We show that reproductive females move more quickly during migration than non-reproductive females. Further, the loss of a calf over the course of migration triggered a decrease in speed of the female. This is in contrast to what might be expected for females no longer constrained by an accompanying offspring. The observed patterns demonstrate that females of different reproductive status may have distinct movement patterns, and that the underlying motivation to move may be altered by a change in reproductive status during migration.
Movement-based methods to infer parturition events in migratory ungulates
Canadian Journal of Zoology, 2018
Long-distance migrations by ungulate species are a globally imperiled natural phenomenon and conservation of them requires monitoring population vital rates. Satellite telemetry tracking is widely used for understanding the spatial distribution and movement of animals, especially migratory animals in remote environments. Recently, analytical methods have been developed to infer parturition events from movement data in multiple species that calve in isolation, but to date such methods have not been tested on animals that both migrate and spatially aggregate during calving. We applied two movement-based methods developed to infer parturition in nonmigratory woodland caribou (Rangifer tarandus caribou (Gmelin, 1788)) to 241 reproductive seasons spanning 6 years of GPS data from migratory barren-ground caribou (Rangifer tarandus granti J.A. Allen, 1902). We compared results from both methods to data from aerial surveys of collared females during the calving period. We found that each mo...
Summer Movements of Female Moose and Dispersal of Their Offspring
The Journal of Wildlife Management, 1987
Fifty-seven radio-equipped moose (Alces alces) in central Sweden were located during the 3 summers of 1980-83. Forty-two were cows (22 years old) and 15 were calves (5 males and 10 females) when captured. Aerial tracking was conducted -1 time/week. No significant differences in average size of summer home ranges were found between age classes. All cows returned to the same summer range each spring. Consecutive summer home ranges overlapped from 1 to 100%. Ten of 14 radio-equipped calves accompanied their cow to summer ranges. The 1st indications of separation between cow and offspring were recorded from 7 to 29 May. The average straight line distance between cow and offspring successively increased from separation to mid-June when it became relatively constant (1.5-2.0 km). One of 10 calves that completed the migration together with the cow abandoned its mother's home range completely. Adult female offspring continued to reside near their yearling home range during consecutive summers.
From migration to nomadism: movement variability in a northern ungulate across its latitudinal range
Ecological Applications, 2012
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 dataset of 213 individual moose (Alces alces) across a latitudinal gradient (from 56° to 67° N) that spans over 1,100 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. Hence, heterogeneity in the immediate environment can result in multiple movements within a species. 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 earlier 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.
The Seasonality of a Migratory Moose Population in Northern Yukon
2020
At the northern edge of their North American range, moose (Alces alces) occupy treeline and shrub tundra environments characterized by extreme seasonality. Here we describe aspects of the seasonal ecology of a northern Yukon moose population that summers in Old Crow Flats, a thermokarst wetland complex, and winters in surrounding alpine habitat. We collared 19 moose (10 adult males and 9 adult females) fitted with GPS radio-collars in Old Crow Flats during summer, and monitored their year-round habitat use, associated environmental conditions, and movements for 2 years. Seventeen of 19 moose were classified as migratory, leaving Old Crow Flats between August and November and returning in April to July, and spent winter in alpine habitats either northwest (n = 8), west (n = 4), or southeast (n = 5) of Old Crow Flats. The straight-line migration distance between summer and winter ranges ranged from 59 to 144 km, averaging 27 km further for bulls than cows. In summer, 18 of 19 moose si...