Climate change impacts on animal migration

Commentary This is the first in a regular series of mini-review which highlight outstanding recently published papers that shed new light on biological responses to climate change. We chose migration as the topic for the first mini review because its global geographical scale makes migrating individuals particularly vulnerable to climate change, and at the same time, the process of migration has fundamental impacts on ecological processes and biodiversity. Movement is an integral part of the ecology of many animals, and it can affect individual fitness and population persistence by enabling foraging and predation, behavioural interactions, and migration 1. Migration, in particular, affects biodiversity at regional and global scales, and migratory animals affect ecosystem processes. Animals use predictable environmental cues for the timing and navigation of migration. A change in these cues will affect the phenology and extent of migration. Arrival date and hatching date are phenological markers in migrating birds, for example, that can be strongly affected by global warming. These dynamics have been incorporated into a mathematical model recently 2. Higher temperatures cause earlier appearance of the insect prey of hatchling birds, which exerts pressure on birds to breed earlier so that hatchling development coincides with peak prey abundance. Advanced breeding is dependent on the arrival time of the adults at the breeding site, as well as the delay between arrival and the start of breeding. These traits can change synchronously or asynchronously, and a mismatch between prey abundance and hatching can cause population declines. The mathematical model 2 explores the dynamics of these interactions and their evolutionary trajectories, and it can explain patterns observed in European flycatchers. Conversely, departure from their non-breeding grounds in Africa also appears to occur earlier for at least some Palearctic migratory birds 3. Hence, there is a global