Posted by: Dan | April 15, 2009

Climate Change May Mean Longer Migrations

The Whitethroat may face an added 300 miles to its migration from Africa to Europe by the end of the century

The Whitethroat may face an added 300 miles to its migration from Africa to Europe by the end of the century

Tiny warbler at risk from longer African migration, as European breeding ranges shift northwards:

They are some of the world’s most remarkable and improbable journeys – vast odysseys across desert, mountain and sea by creatures often no bigger than a Mars bar. But the annual flights of Europe’s migratory birds to and from sub-Saharan Africa are set to get even longer.

Climate change, shifting the breeding range of many European bird species northwards, is likely to lengthen the migrants’ marathon journeys substantially, in some cases by hundreds of miles, a new scientific study predicts. The added distance is likely to make what are already hazardous and chancey long-distance flights even more risky, with possible fatal consequences for many birds.

The article continues…

The researchers have carried out the first examination of how global warming may, by the end of the century, affect the “climate space” of European breeding birds on their wintering grounds in Africa – the climate space being the climatic range in which they can comfortably exist. This is a follow-up to a study last year, extensively reported in The Independent, which showed that many birds’ climate space in Europe would shift towards the north as temperatures rose.

But the new study shows that for the bird group studied – the Sylvia family of warblers, of which the whitethroat (Sylvia communis) is one – the African climate space does not move in some cases, while the European one does, meaning that the migratory journey gets longer.

[…]Three more of the warbler species face increased distances on their migratory journeys from sub-Saharan Africa as long as, or longer than, those faced by the whitethroat, the study shows. These are birds of central and southern Europe which are not often found in Britain.

  • The first is the Subalpine Warbler, Sylvia cantillans, a very pretty songbird with an orange breast set off by a white “moustache” which is found in southern Europe, especially around the Mediterranean coast. It faces an average increase in its journey of about 470 miles.
  • The second is the Orphean Warbler, Sylvia hortensis, which looks rather like a larger version of the blackcap familiar to English bird lovers, which has a very similar range to the subalpine. It faces an increase in its journey of about 340 miles.
  • The third is the Barred Warbler, Sylvia nisoria, a fairly inconspicuous bird of an ashy grey-brown colour, which migrates to breed in central and eastern Europe. It faces an average increase in its annual journeys of nearly 600 miles.

The researchers only studied 17 bird species in total and it is quite possible that many more migrants to Europe from Africa may face longer annual journeys.

This study was also described in press release at Alpha Galileo, and published in the Journal of Biogeography.

A few thoughts…

First, it’s nice to see studies like this being done in Europe. Sure, I’m American, but being that I’m living in Europe, it seems to me that the American ornithological community is much more developed, making me really appreciate the smaller but vibrant European ornithological community.

Second, they appear to have focused on Sylvia warblers using simulation models, meaning that we should note that this is projected and not yet actual, but also that these projections may or may not apply to other migrants.

And third, would this impact population sizes, and to what extent?

Doswald, N, et al., J. Biogeography 2009 [Adv Online]
DOI: 10.1111/j.1365-2699.2009.02086.x



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