Ecology: Migration associated with faster pace of life

Migratory birds and mammals live faster paces of life — live shorter lives, develop faster, and produce more offspring, more quickly — than their non-migratory relatives, according to a global analysis. The findings, published in Nature Communications, could have implications for predicting how birds and mammals with different life histories will respond to environmental change.

Migration is costly, yet billions of animals migrate every year and it is unclear how life history strategies such, as lifespan, developmental and fertility rates may differ between migratory and non-migratory species.

After controlling for evolutionary history, body size and geographic location, Stuart Bearhop, Andrea Soriano-Redondo and colleagues compared over 700 bird and 540 mammal species to investigate how migration and life history might be related. They find that migratory species have a faster pace of life than their non-migratory relatives. This result supports existing work that predicts a trade-off between the time, energy and risk associated with migration, and an organism’s investment in survival and reproduction. The authors also found that among swimming and walking species, migrants tend to be larger, while among flying species, such as bats and most birds, migrants are smaller. They suggest this is because the energetic costs of migration scale differently with body size for swimming and walking versus flying.

The findings could have implications for predicting which species are more likely to be influenced by environmental change, the authors conclude, and they call for more research on relatively understudied migratory groups like reptiles, amphibians and insects.