Planet Ark : Scientists Puzzled by Synchrony of
Migratory Birds in UK: October 8, 2004

http://www.planetark.com/dailynewsstory.cfm/newsid/27585/story.htm

LONDON - They rarely see each other, spend winters in
different countries and don't communicate for long
periods but pairs of a species of Icelandic migratory
birds know exactly when to return home to breed.

The couples of black-tailed godwits somehow manage to
coordinate their journeys, from different countries
up to 1,000 km apart, to arrive back at their Iceland
breeding grounds within about three days of each
other.

"When males and females from a pair arrive back on
their breeding territory in the spring, they do so
with remarkable synchrony," Jill Gill, of the
University of East Anglia said in an interview. "We're
astonished by it."

Scientists had assumed that males and females of
migratory bird species stayed together during the
winter and traveled back with each other to their
breeding grounds.

"In this particular species, the males and females are
going to completely different locations, often
different countries, so they are wintering on average
1,000 miles apart," said Gill, who reported the
findings in the science journal Nature.

"And yet they are getting back somehow to the breeding
ground within two or three days of one another." It
takes about a month for the entire population of
godwits, which stand about 8 inches tall and weigh
roughly 10 ounces, to get back to Iceland from their
wintering spots dotted around Europe.

Couples manage to time it with extraordinary accuracy
but if one of them gets it wrong, their partner takes
up with another male or female.

"We have had two cases of divorce," said Gill. "In
both cases the female got back before the male." Tired
of waiting, both females mated with other males.

Gill and her colleagues discovered the unusual talent
of the Icelandic black-tailed godwits with the help of
a huge network of birdwatchers throughout Europe.
Researchers tagged the birds and volunteers took note
of when the godwits arrived and left.

"We get hundreds of sightings from people right across
Europe so we are able to work on a large scale," said
Gill. But she and her team are perplexed about how the
birds get it right.

"We know they don't meet up in the wintering grounds
and they don't meet up on passage. The first time they
see each other is when they arrive on the territory,"
Gill said.

"Our suspicion is that what we see in the godwits may
be true for many other species as well."

Story by Patricia Reaney

REUTERS NEWS SERVICE


=====
Devorah A. N. Bennu, PhD
Independent Scholar
birdologist [at] yahoo [dot] com
public blog: http://girlscientist.blogspot.com



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