Long-distance, synchronized and directional fall movements suggest migration in Arctic hares on Ellesmere Island (Canada)

Abstract

Animal migration contributes largely to the seasonal dynamics of High Arctic ecosystems, linking distant habitats and impacting ecosystem structure and function. In polar deserts, Arctic hares are abundant herbivores and important components of food webs. Their annual migrations have long been suspected, but never confirmed. We tracked 25 individuals with Argos satellite telemetry to investigate the existence of migration in a population living at Alert (Ellesmere Island, Nunavut, Canada). During fall, 21 hares undertook directional, long-distance movements in a southwestern direction towards Lake Hazen. Daily movement rates averaged 1.3 ± 0.5 km, 4.3 ± 1.6 km, and 1.7 ± 0.9 km before, during, and after relocation, respectively. Straight-line and minimum cumulative distances traveled averaged 98 ± 18 km (range: 72–148 km) and 198 ± 62 km (range: 113–388 km), respectively. This is the first report of large-scale seasonal movements in Arctic hares and, surprisingly, in any lagomorph species. These movements may be part of an annual migratory pattern. Our results redefine our understanding of the spatial ecology of Arctic hares, demonstrate unsuspected mobility capacities in lagomorphs, and open new perspectives regarding the ecological dynamics of the northern polar deserts.

Vegetation biomass and topography are associated with seasonal habitat selection and fall translocation behavior in Arctic hares

“…Capture and handling techniques were approved by the Animal Care Committee of Université du Québec à Rimouski (CAC-68-17-184) and the Government of Nunavut (WL 2018-020). Our sample size consisted of 21 females, including 17 that were confirmed breeders, and 4 males (details in Caron-Carrier et al 2022 ). The dataset generated and analyzed for this study is part of the Arctic Animal Movement Archive (Davidson et al 2020 ), is freely available in MoveBank (Wikelski et al 2021 ), and is stored in the MoveBank Data Repository (Berteaux 2021 ).…”

“…We filtered the dataset based on a 5 km/h cruising speed threshold (with possible acceleration bouts of 10 km/h for locations less than 10 min apart) using a speed filter implemented in R (version 4.1.1; R Core Team, 2021 ). We used locations with Argos location classes 1 (1500-m isotropic error), 2 (500 m), 3 (250 m), and A (no error estimation) (Christin et al 2015 ), and kept one location per day per individual based on the smallest error obtained (Caron-Carrier et al 2022 ).…”

“…We determined each phase of the seasonal cycle (summer residency, winter residency, fall relocation) for each individual based on their average daily movement rates (details in Caron-Carrier et al 2022 ). Locations of resident hares were included in the summer residency dataset if collected before the date of departure of the last relocating hare.…”

“…Some populations display short seasonal range shifts (Hearn et al 1987 ; Small et al 1991 ), but Arctic hares were until recently considered largely resident, like all other lagomorphs. However, Caron-Carrier et al ( 2022 ) reported large-scale (ca. 100 km), synchronized and directional fall movements of Arctic hares on northeastern Ellesmere Island (Canada).…”

“…100 km), synchronized and directional fall movements of Arctic hares on northeastern Ellesmere Island (Canada). These movements could be part of a seasonal migration triggered by the large-scale resource heterogeneity of the polar desert (Caron-Carrier et al 2022 ; Lai et al 2022 ), but determining Arctic hare habitat selection across seasons is required to better understand the drivers of this outstanding behavior.…”