Migration statistics and animal biometrics for mule deer that migrated long-distances (2011–2020), Wyoming, USA

Billions of animals migrate to track seasonal pulses in resources.
Optimally timing migration is a key strategy, yet the ability of animals
to compensate for phenological mismatches en route is largely unknown. We
studied a population of mule deer (Odocoileus hemionus) in Wyoming that
lack reliable cues on their desert winter range, causing them to start
migration 70 days ahead to 52 days behind the wave of spring green-up. By
adjusting movement speed and stopover use, however, individual deer arrive
at the summer range within an average 6-day window. Late migrants move 2.5
times faster and spend 72% less time on stopovers than early migrants,
which allows them to catch the green wave. Ungulates, and potentially
other migratory species, possess cognitive abilities to recognize where
they are in space and time relative to key resources. Such behavioral
capacity may allow migratory taxa to maintain foraging benefits amid
rapidly changing phenology.