With climate change, birds are taking off for migration sooner; not reaching destinations earlier

Jan 28, 2010

Migrating birds can and do keep their travel dates flexible, a new study published online on January 28th in Current Biology reveals. But in the case of pied flycatchers, at least, an earlier takeoff hasn't necessarily translated into an earlier arrival at their destination. It appears the problem is travel delays the birds are experiencing as a result of harsh weather conditions on the final leg of their journey through Europe.

The discovery may in a sense be good news as far as birds' potential to cope under climate change, but it also highlights the vulnerability of long-distance migrants to environmental conditions in general.

"We have been claiming for a while that have difficulties in adapting to climate change because of their rigid and rather inflexible timing of spring migration; in Africa and South America, they cannot know when spring starts at their northern breeding grounds," said Christiaan Both of the University of Groningen in The Netherlands. "This study shows that timing of spring migration is flexible and that do respond to climate change, although in a rather indirect way: breeding dates have become progressively earlier, and birds are thus born earlier in the spring. We now show that the effect of early birth is also that the birds migrate early, and migration time has advanced over the last 25 years. The reason that the birds did not advance their arrival is thus not due to a failure to start migration earlier, but because circumstances at passage in Southern Europe have not improved."

Pied flycatchers are one of the best-studied migratory bird species in the world. With records going back more than 50 years, researchers have been able to investigate the birds' reaction to climate change over time. Pied flycatchers are also forest-dwelling, which makes them particularly interesting because of the strong seasonality in food dynamics in the forest.

"Forests are characterized by a short burst of rather early in spring," Both explained. "If the birds miss this insect peak for raising their chicks, they do not produce enough offspring to keep up their population sizes."

Like many migrants, pied flycatchers must tackle a rather remarkable and grueling trek each spring to reach their breeding sites. They spend their winters in Western Africa, anywhere from 5000 to 9000 kilometers from their breeding grounds across Europe and western Siberia. Their wintering grounds in Africa become progressively drier over the course of the season, and by the end of that dry spell, they somehow have to accumulate enough resources to fly about 2000 kilometers across the Sahara desert. The birds recover in Northern Africa before heading to their final destinations.

"Based on our calculations, they are covering the distance from Northern Africa to The Netherlands in about 6 days, and to central Sweden in about 12 days," Both said. Only a small fraction of birds make it through that harrowing journey. For those that do, "in some of the northern or eastern breeding grounds, the first birds often arrive when the breeding areas are still snow-covered. And these birds are strictly insectivorous—earlier arrival probably means death because there are not enough insects to be found." In The Netherlands, circumstances are better at arrival, he added, but the birds there get little or no chance to rest before breeding and nest building must begin. In most cases during the warm springs of the past decade, birds in The Netherlands have laid their first eggs 7 to 8 days after completing their journey.

Both's team found that the birds left their wintering grounds and made it all the way to Northern Africa 10 days earlier in the year in 2002 than they did in 1980. Still, they didn't arrive at their European breeding grounds any sooner.

The findings imply that "little should be expected in terms of an evolutionary response [to climate change]: any genetic variation in spring departure is likely to be masked by environmental constraints and not translated into earlier arrival," the researchers conclude. "More generally, because often alters temperatures differently at different periods in the year, adaptation of life cycles in animals with a complex annual cycle is not likely to be solved by simple phenotypic or evolutionary responses toward earlier phenology. An adaptive evolutionary response most likely is needed on a whole suite of different traits simultaneously, and it remains to be seen whether evolution can alter species quickly enough to stop their decline."

Explore further: Male monkey filmed caring for dying mate (w/ Video)

add to favorites email to friend print save as pdf

Related Stories

'Early birds' adapt to climate change

May 09, 2008

Individual birds can adjust their behaviour to take climate change in their stride, according to a study by scientists from the University of Oxford.

Recommended for you

Male monkey filmed caring for dying mate (w/ Video)

Apr 18, 2014

(Phys.org) —The incident was captured by Dr Bruna Bezerra and colleagues in the Atlantic Forest in the Northeast of Brazil.  Dr Bezerra is a Research Associate at the University of Bristol and a Professor ...

Orchid named after UC Riverside researcher

Apr 17, 2014

One day about eight years ago, Katia Silvera, a postdoctoral scholar at the University of California, Riverside, and her father were on a field trip in a mountainous area in central Panama when they stumbled ...

In sex-reversed cave insects, females have the penises

Apr 17, 2014

Researchers reporting in the Cell Press journal Current Biology on April 17 have discovered little-known cave insects with rather novel sex lives. The Brazilian insects, which represent four distinct but re ...

Fear of the cuckoo mafia

Apr 17, 2014

If a restaurant owner fails to pay the protection money demanded of him, he can expect his premises to be trashed. Warnings like these are seldom required, however, as fear of the consequences is enough to ...

User comments : 0

More news stories

Biologists help solve fungi mysteries

(Phys.org) —A new genetic analysis revealing the previously unknown biodiversity and distribution of thousands of fungi in North America might also reveal a previously underappreciated contributor to climate ...

Researchers successfully clone adult human stem cells

(Phys.org) —An international team of researchers, led by Robert Lanza, of Advanced Cell Technology, has announced that they have performed the first successful cloning of adult human skin cells into stem ...

NASA's space station Robonaut finally getting legs

Robonaut, the first out-of-this-world humanoid, is finally getting its space legs. For three years, Robonaut has had to manage from the waist up. This new pair of legs means the experimental robot—now stuck ...

Ex-Apple chief plans mobile phone for India

Former Apple chief executive John Sculley, whose marketing skills helped bring the personal computer to desktops worldwide, says he plans to launch a mobile phone in India to exploit its still largely untapped ...

Filipino tests negative for Middle East virus

A Filipino nurse who tested positive for the Middle East virus has been found free of infection in a subsequent examination after he returned home, Philippine health officials said Saturday.

Egypt archaeologists find ancient writer's tomb

Egypt's minister of antiquities says a team of Spanish archaeologists has discovered two tombs in the southern part of the country, one of them belonging to a writer and containing a trove of artifacts including reed pens ...

Airbnb rental site raises $450 mn

Online lodging listings website Airbnb inked a $450 million funding deal with investors led by TPG, a source close to the matter said Friday.