Climate change and human pressure mean migration may be “no longer worth it”, say researchers

Climate change and human pressure mean migration may be “no longer worth it”, say researchers - University of Bath

Polar Bears stranded on the land are recently increasing predation pressure on migratory birds such as these Brant geese. (Credit: Vojtěch Kubelka)

Researchers have found that the benefits of migration have been eroded by the effects of climate change and human pressure.

Animals that migrate north to breed are being put at risk by ongoing climate change and increasing human pressure, losing earlier advantages for migration, declining in numbers and faring much worse than their resident counterparts, according to scientists writing in Trends in Ecology & Evolution.

Many animals, including mammals, birds and insects migrate long distances north to breed, taking advantage of the seasonally plentiful food, fewer parasites and diseases, and the relative safety from predators.

However, the international research team, including scientists from the University of Bath, found changes in climate and increasing human pressure have eroded these benefits and in many cases led to lower reproductive success and higher mortality in migrating species.

The researchers warn that reduced advantages for long-distance migration have potentially serious consequences for the structure and function of ecosystems.

They highlighted 25 recent studies, describing how migration is becoming less profitable for various terrestrial animals, including caribou, shorebirds and Monarch butterflies, which migrate over 1000km during the summer to north temperate and arctic regions to breed, returning south in the winter.