December 8th, 2012 by James Ayre
The Horn of Africa experienced a massive drought last year that greatly affected many millions of people. And according to new research, it also had a great effect on several species of songbirds, greatly delaying their migration to Northern Europe.
The data used in the research was gathered via ‘small backpacks’ that were fitted onto birds, and it showed that the delay was caused because of the birds spending more time in the drought stricken Horn of Africa.
“The extensive 2011 drought in the Horn of Africa had significant consequences for European songbirds such as thrush nightingale and red-backed shrike. These birds visit northern Europe every spring to mate and take advantage of ample summer food resources.”
The migration route that these birds take from southern Africa to northern Europe goes directly through the Horn of Africa though, and they’re reliant on the local resources there to feed and stock up the caloric resources they will use for the trip.
“Our research was able to couple the birds’ delayed arrival in Europe with that stopover in the Horn of Africa. Here they stayed about a week longer in 2011 than in the years before and after 2011. Because of the drought, the birds would have needed longer to feed and gain energy for their onward travel, causing delayed arrival and breeding in Europe. This supports our theory that migrating animals in general are dependent on a series of areas to reach their destination,”says Associate Professor Anders Tøttrup from the Center for Macroecology, Evolution and Climate at the University of Copenhagen.
The birds late arrival in Europe was something of a mystery until now. This is especially true when you factor in their progressively earlier and earlier arrival over the past 50 years as climate change has been occurring.
“By placing small data loggers on the backs of several birds in the autumn before their migration to Africa, and retrieving them in the spring when the birds returned to Europe, the scientists were able to trace the migration route and stopover sites. These data revealed a delay in the particular stopover in the Horn of Africa. Additionally, it was noted that other migrating birds not passing through the Horn of Africa arrived in Europe at the expected time.”
“We have reconstructed 26 migration routes based on data from the small ‘data backpacks’ weighing just 1 gram. This new technology provides us with a detailed picture of the birds’ migration and stopovers. It is brand-new territory to be able to track animals this small over such great distances,” says Associate Professor Kasper Thorup from the Center for Macroecology, Evolution and Climate at the University of Copenhagen.
The late arrival of the birds in 2011 also led a later breeding year than been the case previously.
“There are no signs of implications on the birds’ breeding success and thereby the size of the population. But it is possible that we haven’t yet seen the full effect of the delayed year,” concludes Anders Tøttrup.
The study was just published December 6th in the journal Science.
Source: University of Copenhagen
Image Credits: Mikkel W. Kristensen; Per Ekberg
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