Migrant birds face risk in earlier springs
A great tit preys on a pied flycatcher. Image: By Maurice van Laar
Spring in the high latitudes is arriving ever earlier. But migrant birds from the tropics may not realise that, and faulty timing could cost them their lives.
LONDON, 11 January, 2019 – Biologists have identified another tale of conflict and bloodshed as African migrant birds compete with European natives for resources in a fast-warming world.
Death rates among male pied flycatchers – African carnivores that migrate each spring to the Netherlands to breed – have risen in the 10 years between 2007 and 2016, as winters have warmed and springs have arrived earlier.
And in some years, almost one in 10 of the male migrant flycatchers has been found pecked to death by great tits that have already taken up residence in nest boxes that both species favour.
Jelmer Samplonius, then of the University of Groningen and now at the University of Edinburgh in Scotland, and a colleague report in the journal Current Biology that they became interested in the competition between the migrant Ficedula hypoleuca and the European garden bird Parus major because both compete for the same resources.
These are the spring explosion of the caterpillar population, and the nest boxes established by householders who like to encourage wildlife. Both species try to time their breeding calendar to coincide with the arrival of plentiful, nourishing food for their chicks, and both species have become accustomed to colonising available nest boxes.
“When a flycatcher enters a box with a great tit inside, it doesn’t stand a chance”
But, the scientists say, climate change driven by global warming, in turn fired by profligate combustion of fossil fuels that increase the ratios of greenhouse gases in the atmosphere, has brought new challenges.
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