News: Other Falcons

[The Peregrine Chick]

23 January

Just heard on the Manitoba birding loop that a gyrfalcon was spotted along Hwy 12 moving northeast.  They usually overwinter in the South Dakota area.  Not time for their northward migration, so someone has decided on a bit of a walk-about ... hopefully it isn't because prey (small mammal) populations are low down south ...

[Alison]

Migratory route of Eleonora's falcon revealed for first time in the Western Mediterranean

16-Oct-2009

Satellite tracking has allowed a research team to uncover the mysteries of the migration of Eleanora's falcon for the first time. In total, the bird flies more than 9,500 kilometres across the African continent from the Balearic and Columbretes Islands before reaching the island of Madagascar. Some of the previously-obscure secrets now revealed by the scientists show that these falcons migrate by both day and night, and cross supposed ecological barriers such as the Sahara Desert.



Until recently, the scientific community had almost no knowledge of the biology and life strategies of Eleanora's falcon (Falco eleonorae), a migratory bird of prey with low population numbers that nests on marine islands. However, researchers from the Universities of Valencia (UV) and Alicante (UA) tagged 11 individuals (7 adults and 4 chicks) in the colonies of the Balearic Islands between 2007 and 2008 and in the Columbretes Islands in the province of Castellón in 2008, with a further five individuals tagged in 2009.

"This represents a landmark in the study of this species, because to date nobody had been able to catch any Eleanora's falcon individuals and tag them using satellite technology anywhere in their colonies in the western Mediterranean", Pascual López, a researcher at the UV and lead author of the study, which has been published recently in the journal Zoological Studies, tells SINC.

The tagged falcons started their migration of more than 9,500 kilometres in the autumns of 2007 and 2008, travelling from the Balearic Islands to Madagascar. The new discovery made by this study was that the falcons do not fly over the waters of the Mediterranean and along the East African coast, but instead cross straight over the African continent.

The satellite tracking data have also shown that "Eleonora's falcons can migrate by both day and night (a new discovery among birds of prey of their genus), and cross supposed ecological barriers such as the Sahara Desert, the Equator and extensive stretches of open sea in the Indian Ocean", points out López.

During the two-month migration undertaken by the falcons in order to winter in Madagascar, the biologists received hundreds of position signals for the adults (throughout 10 countries) and the juveniles (in 14 countries). Their migratory route to return to Europe in the spring once again crosses the African continent, "but they follow a completely different path from that used for the autumn migration, flying for more than 1,500km non-stop over the Indian Ocean from Madagascar to Somalia, a phenomenon that has never before been described in birds of prey of this genus, and which pushes them to the limits of their physiological capacity ", says the researcher.

A very special bird

Some of the peculiarities of this bird of prey, which migrates over long distances and evolved only recently, include "a reproductive cycle adapted to the migration of other bird species, starting at the end of the summer and not in the spring (the latest among all European birds of prey). This makes it a model organism for looking into questions about its phylogeography and evolution", adds López, who also wants to find out how the Eleonora's falcons manage to navigate during such a long journey.

Eleonora's falcon was named after Giudicessa Eleonora de Arborea (1350-1404), a Sardinian princess who fought for Sardinia's independence from the Kingdom of Aragon, and who drafted the first laws in Europe protecting birds of prey.

References:

López-López, Pascual; Limiñana, Rubén; Urios, Vicente. "Autumn Migration of Eleonora's Falcon Falco eleonorae Tracked by Satellite Telemetry" Zoological Studies 48(4): 485-491, julio de 2009.

http://www.eurekalert.org/pub_releases/2009-10/f-sf-mro101609.php

[carly]

2,500-year-old bird's nest found


Good for generation after generation

A 2,500-year-old bird's nest has been discovered on a cliff in Greenland.  The nesting site is still continually used by gyrfalcons, the world's largest species of falcon, and is the oldest raptor nest ever recorded.  Three other nests, each over 1,000 years old, have also been found, one of which contains feathers from a bird that lived more than 600 years ago. However, ornithologists fear climate change may soon drive the birds from these ancient nesting sites.

Gyrfalcons live circumpolar to the Arctic. The birds range in colour from being almost exclusively white in Greenland to usually black in Labrador in Canada. Like many falcons, they do not build nests out of sticks and twigs, but typically lay eggs in bowl-shaped depressions they scrape into existing ledges or old nests made by other birds such as ravens.

But while stick nests are often frequently damaged, preventing their repeated use, gyrfalcons will often revisit some ledges and potholes from year to year. To find out just how long the birds return to the same site, ornithologist Kurt Burnham of the University of Oxford, UK and colleagues decided to carbon date the guano and other debris that birds leave at various nest sites around Greenland.


An ancient nest, this one dated at a mere 1000 years old.  

The cold dry climate of Greenland slows the decay of the falcons' droppings and various nest sites had built up levels of guano almost 2m deep. But Burnham was still surprised to find out just how old these nests are.

Carbon dating revealed that one nest in Kangerlussuaq in central-west Greenland is between 2,360 and 2,740 years old, the researchers report in Ibis. Three other nests in the area are older than 1,000 years, with the youngest nest site first being occupied 520 to 650 years ago. These ancient nests are still being regularly used by gyrfalcons.

"While I know many falcon species re-use nest sites year after year, I never imagined we would be talking about nests that have been used on and off for over 2,000 years," says Burnham.

Within the nests, Burnham's team also found intriguing clues as to the past inhabitants. In the 13 nests sampled, they found three feathers belonging to previous tenants. The youngest came from a bird residing in the nest 60 years ago, while the oldest came from a falcon that used the nest some 670 years ago.

The ancient guano samples also gave an indication of what the birds ate in times long past.


The world's largest falcon.
 
Those gyrfalcons living in central-west Greenland, which is farther from the ice sheet and nearer the ocean, fed from a diet much richer in marine animals, such as little auks and black guillemots. Falcons living further north closer to the ice fed on terrestrial prey such as rock ptarmigan and arctic hare.

"These findings put new emphasis on just how important nest site characteristics can be for raptor species, particularly large raptors," Burnham says. "Something, be it nest ledge depth, or the amount of cliff overhang above the nest, is so attractive at these locations that gyrfalcons are re-using them for thousands of years."

Yet the fact that gyrfalcons remain faithful to certain nest sites for hundreds of generations suggest that they may be especially vulnerable to climate change, says Burnham.

"As a result of a warming and ameliorating climate other bird species, such as peregrine falcons, are moving further north. As peregrine populations continue to increase in density they will likely use more and more of these traditional gyrfalcon nests, forcing gyrfalcons to find alternate locations to nest in which may not offer the same amount of protection from the harsh Arctic environment in Greenland."

Similar studies have been used to show when whole colonies of birds first took up residence at certain sites.

By carbon dating solidified stomach contents, peat moss deposits and bone and feather samples from various moulting sites, researchers have in the past shown that colonies of snow petrel have returned to the same sites for 34,000 years and adelie penguins for 44,000 years.

http://news.bbc.co.uk/earth/hi/earth_news/newsid_8103000/8103872.stm

http://www.telegraph.co.uk/earth/earthnews/5558845/Falcon-nest-in-Greenland-is-2500-years-old.html