Abstract

In northern environments, the period of access to high-quality forage is limited, exerting strong selective pressure to optimize the timing of parturition. We analysed timing and variation in moose (Alces alces) parturition dates of 555 females at 18 study sites across 12 degrees of latitude (56-68 degrees N, 1350 km) in Sweden. We found evidence for a spatial match of parturition timing to vegetation onset, but no evidence that moose adjust parturition to vegetation onset in a given year. We found a breakpoint at 64 degrees N. Despite adaptation across latitudes, temporal divergences occurred. Females below 64 degrees N calved after vegetation onset and females above 64 degrees N calved before. Here, parturition before vegetation onset might be a strategy to optimize forage utilization time with the very short growing season. Highly seasonal environments such as at higher latitudes may make it advantageous to adapt parturition towards long-term climatic patterns by matching the most favourable period. Given the direction of temporal divergence, our study suggests that climate change may have less of an impact on moose parturition at northern latitudes than southern latitudes.

Keywords

Alces alces; ungulate; calving; birth date; phenology

Published in

Biology Letters
2020, volume: 16, number: 6, article number: 20200044
Publisher: ROYAL SOC

Authors' information