Flexibility in the face of climate change? A rapid and dramatic shift toward later spring migration in Hudsonian godwits (Limosa haemastica)

With rapid environmental change, shifts in migration timing are vitally
important for maintaining population stability in migratory species and
have been widely documented. However, little remains known about how
migrants make these shifts and what factors influence the utilization of
these strategies, limiting our ability to assess their vulnerability to
climate change. Hudsonian godwits (Limosa haemastica) are an extreme
long-distance migratory shorebird that (1) have previously shifted their
population-level migration timing and (2) are sexually dimorphic. We
combined over a decade of tracking data from one breeding population with
a historical predictive model to assess on-going shifts in migration
timing and investigate potential sex-specific migration strategies. We
found that godwit departure and arrival timing shifted 6 days later from
2010-2023 with no differences in timing between the sexes. The population
maintained an average migratory duration of 24 days and drove shifts in
arrival timing entirely by changing their nonbreeding ground departure.
Yet, we also found that godwits arrived later than predicted by the
historical model, indicating this response may not be adaptive. These
results emphasize the urgent need for a more holistic approach to
assessing the vulnerability of migratory species and the adaptiveness of
changes in migration timing.