Strength of seasonality and type of migratory cue determine the fitness
consequences of changing phenology for migratory animals
Abstract
Phenological mismatch has been highlighted as a reason why climate
change is causing declines of migratory populations. The likelihood of
declines due to phenological mismatch might depend on what cues trigger
migration. Migrants that use environmental cues (e.g. temperature,
resource availability) to trigger migration are often considered to be
less vulnerable than migrants that use temporal information (e.g.
photoperiod). We develop a model to investigate how migration cue type
determines the effects of phenological change of habitat quality on
fitness. We show that which cue type performs better depends on the
strength of seasonality in the habitats used by a migrant. We use our
results to identify scenarios that align and contrast with the
prediction that migrants using temporal cues are more vulnerable. We
also recommend that future empirical and theoretical work on
phenological mismatch more clearly distinguish between the accuracy and
efficacy of cues. Similarly, we recommend considering both how the
benefits available from migrating and the benefits that are captured by
migrants are changing with phenological change. This work improves our
understanding of the role of cue in determining migratory populations’
trajectories as climate changes.