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Half of 24 GPS-Tracked Female Moose Migrated While Repeatedly Selecting Shrubby River Corridors

Female moose standing in vegetation at Potter Marsh, Alaska
Research · Ecology

Half of 24 GPS-tracked adult female moose (Alces alces) near the northern edge of the species’ range migrated between seasonal ranges, while the others remained more resident. This makes the population partially migratory: migratory and non-migratory individuals occur together. Across summer, winter and migration, the animals repeatedly selected river corridors rich in deciduous shrubs and forbs.

Migration was more common in the eastern group

The study followed 24 females in Arctic National Wildlife Refuge from 2022 to 2024, divided into eastern and western groups of 12. Eight eastern females migrated compared with four western females. Eastern migrants followed relatively concentrated routes through mountainous river headwaters to Old Crow Flats in Canada’s Yukon Territory and returned in autumn, whereas western migrants used more diffuse routes between river valleys and the coastal plain.

Migration was not necessarily a fixed individual strategy. Of the 21 females tracked for more than one year, two switched between migratory and non-migratory behaviour in different years.

Riverine deciduous shrubs were selected year-round

Despite differences in route structure, the habitat signal was strikingly consistent. In both summer and winter the moose selected deciduous shrubs and forbs near rivers and generally avoided rugged terrain and evergreen shrub cover. In summer they also avoided graminoid-dominated areas, while in winter they selected broadleaf trees in addition to shrubs and forbs.

The same pattern appeared while animals were moving between seasonal ranges. Migrating moose selected low-elevation terrain near rivers with deciduous shrubs. During spring migration they strongly avoided deep snow and higher elevations, while during autumn migration they selected cooler conditions. River valleys therefore appear to combine relatively easy travel with the woody browse on which moose depend.

Expanding Arctic shrubs could increase suitable habitat

Tall willow and birch communities along rivers provide concentrated forage in an otherwise strongly seasonal tundra landscape. The authors suggest that continued expansion of deciduous shrubs across Arctic tundra could facilitate further northward expansion by moose. That is an ecological implication of the observed habitat preferences rather than a direct forecast of future population growth.

The eastern migration routes also crossed the international boundary between Alaska and Yukon, showing that the seasonal habitat needs of this population span both the United States and Canada.

Sources and image credit

  1. Sattler, R. L., Crane, M., Cameron, M. D., Berkeland, M. S., & Leacock, W. B. (2026). Pronounced and consistent selection of deciduous shrub habitats near waterways during migration, summer, and winter by moose (Alces alces) in a partially migratory Arctic population. Polar Biology, 49, 109.Primary open-access research article published 15 September 2026; full text checked. GPS data from 24 adult female moose captured in Arctic National Wildlife Refuge were analysed across 2022–2024. Half of the animals showed migration, with more migrants in the eastern than western subgroup. Moose consistently selected deciduous shrubs and forbs near rivers, and eastern migrants used concentrated routes to Old Crow Flats in Yukon Territory.

Image: Female moose (Alces alces) at Potter Marsh, Alaska, USA, photographed 22 August 2017. Photo: Diego Delso. Source: Wikimedia Commons. CC BY-SA 4.0. Representative Alaska image; not an identified animal from the study. · CC BY-SA 4.0 · Source

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