Young murres jump to grow faster
Young birds in general have reached at least half of adult size before they leave the nest. Young murres leave the nest at two weeks of age and about one quarter of adult size. If they land safely in the sea they follow their fathers who parent them.
Until now the dominant opinion has been that the murre offspring leave the nest when they are large enough to defend themselves and too large to be fed at land. But now this idea is questioned by researchers.
Together with colleagues in Canada and Denmark Jannie Linnebjerg at the Department of Biology at Lund University has studied murres in five different places in Greenland and Newfoundland. They put recording devices on murre fathers to detect their activity at sea.
One thing the researchers discovered was that the mortality rate did not differ much between the colony and at sea. Another discovery was that murre fathers were able to feed their offspring a lot more at sea compared to when they were still in the nest on the cliffs.
The big advantage at sea is that the murre fathers do not need to ”commute” between sea and land. And so they have much more time and use less energy to find food and feed their young one.
The researchers draw the conclusion that young murres take the leap because they will gain a lot more energy at sea and grow much faster.
The researchers think that their results might have bearing on other animals.
”We think that the size of the young ones is a much more important factor than safety when it comes to decide when adults stop parenting their offspring”, Jannie Linnebjerg says.
The results are presented in an article in The American Naturalist.
Text: Jan Olsson