历史最悠久的鸟窝

2009-07-28 18:29  Read:

科学家在格陵兰发现了2500年老的鸟巢,这个在耶稣诞生之前就存在的窝岌岌可危的位于一个悬崖顶上,它的主人是猎鹰中体型最大的一种:矛隼,又名海东青(这个名字蛮酷的!)。

这种鸟主要生活在北极、格陵兰和北美地区。作为猎鹰这么酷的动物,它们当然不会用自己捡小树枝来编巢,而是找一个凹陷的地方或者其他鸟类(乌鸦之类的)的窝加工一下,然后下蛋。天长日久之后,巢里积累的羽毛和鸟便便越来越多,牛津大学的研究者用放射性碳定年法,确定了最老的鸟巢是在大概距今2740-2360年之前开始使用的。

但是随着全球气候的变化,矛隼可能也要随着它们的猎物向北迁移,同时面对着当地其他竞争者,比如游隼。

Gryfalcon with chicks: Falcon nest found in Greenland is 2,500-years-old
A falcon nesting site has been found in Greenland Photo: JACK STEPHENS
Gryfalcons
Photo: JACK STEPHENS
Gryflacon flying: Falcon nest found in Greenland is 2,500-years-old
Photo: JACK STEPHENS

The nesting site on a precarious cliff edge is still continually used by gyrfalcons, the world's largest species of falcon.

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 it is feared climate change may soon drive the birds from these ancient nesting sites.

Gyrfalcons live around 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 bowel-shaped depressions they scrape into exiting ledges or old nests made by other birds such as ravens.

Over time the nests become full of feathers and guano as the birds revisit the same site year after year.

Kurt Burnham of the University of Oxford, looked at samples taken from the cliffs on steep ledges in Greenland in order to find out how long the birds have been returning.

"Using radiocarbon dating, the oldest nest was shown to have been used for at least 2,740 to 2,360 calendar years before present, with three other nests likely over 1,000 years old. To date, this is the longest continually used (and currently used) raptor nest ever documented," he said.

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.

But the birds may not be in the area for much longer. As a result of climate change gyrfalcons are following prey north and face more competition from other birds species such as peregrine falcons.

The nest is the oldest raptor nest ever discovered but scientists have found evidence of birds returning to nesting sites for even longer periods. Carbon dating has shown snow petrel have returned to the same sites for 34,000 years and adelie penguins for 44,000 years.

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