The population of migratory species declines as moving to the north proves to be less beneficial and potentially dangerous
Unhindered warming of Earth has forced a change in several ecological patterns, and migration of terrestrial animals and birds to the Arctic during summer may be the latest casualty, according to a new report.
Moving to the northern regions is increasingly becoming less beneficial and potentially harmful to these migratory species, an analysis of 25 studies pointed out.
Each summer, thousands of birds, animals and insects travel long distances north for easy availability of food, less chances of contracting diseases and fewer predators. But rising temperatures in the Arctic region has turned this flourishing arrangement on its head.
Researchers who wrote the paper published in Trends in Ecology and Evolution said:
Numerous Arctic and North temperate sites may now represent ecological traps or even worse degraded environments for diverse migratory animals, including shorebirds, caribou or butterflies.
The ultimate outcome of this crisis is a decline in the population of the migratory species for whom travelling to the north is instrumental to survival during the warm months, the paper noted.
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Many birds, who traditionally seek refuge in the northern regions in summer, have incurred higher mortality of offsprings due to dwindling food supply, the scientists wrote.
New parasites and pathogens have also emerged in the Arctic, according to the report. A combination of these local changes due to climate change have decreased the population of native prey, forcing the predators to turn to migratory individuals.
Lemmings and voles used to be the main food source for predators such as foxes in the Arctic, said Vojtěch Kubelka, lead author of the paper and visiting researcher at the University of Bath's Milner Centre for Evolution. “The milder winters can cause rain to fall on snow and then re-freeze, preventing the lemmings from reaching their food.”
Foxes eat the eggs and chicks of migratory birds as lemmings and voles reduce in numbers, he added.
“We've seen that the rate of nest predation of Arctic migratory shorebirds has tripled over the last 70 years, in large part due to climate change,” Kubelka observed.
The erosion of the natural advantages of migration will have a ripple effect that will alter “species composition, trophic food webs as well as the whole ecosystem functioning”, the researchers predicted.
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Concerted conservation efforts of the breeding grounds in the Arctic and temperate regions in the north is the need of the hour, the authors wrote. They also called for identification of glaring problems at the stopover and wintering sites of migratory species.
Mapping stressors for animals that undertake migration is another area that needs focus, the paper noted. The framework can help demarcate habitats conducive for the migratory species from ‘ecological traps’ or ‘degraded environments’, according to the authors.
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