By measuring body mass and wing length of adult Atlantic Puffins on their breeding grounds and in their wintering areas near the Faroe Islands, researchers have now estimated the seasonal changes in body mass for two populations breeding in Norway and Scotland.
This article was first published at seapop.no.
For pelagic seabirds, which generally lay few eggs per year and invest more in adult survival than reproduction, it is important to build up fat reserves in the body after the breeding season in order to increase the chances of surviving through the winter, when both climate and food availability may be demanding for long periods of time. How much weight they actually gain is hard to assess, since recapturing the individuals that were weighed on the breeding grounds at sea in the winter is normally impossible. In recent years, mapping of seabird migration by the use of geolocators has provided helpful information on where the different populations go outside the breeding season, and we now know, for example, that quite a number of Atlantic Puffins breeding in North-Norway and the southeast part of Scotland spend time near the Faroe Islands in winter. By comparing body mass and wing length of puffins breeding in these areas with corresponding measurements of puffins hunted at the Faroes during the winter, researchers have now estimated the change in body mass of puffins between the breeding and wintering periods more accurately.
Read the article: Fit is fat: winter body mass of Atlantic Puffins Fratercula arctica
Puffins that were shot during the hunting at the Faroes weighed on average 20-30% more than breeding puffins with the same wing length in Scotland and North-Norway. Among the birds hunted in the wintering area were three individuals that had also been weighed and measured on the breeding grounds, and their weight change corresponded well with the changes estimated on the population level. The results of the study indicate that from the chick-rearing in the summer to the wintering stage at the Faroes, puffins put on at least twice the weight they normally lose between incubation and chick-rearing during one breeding season. This knowledge is valuable with regard to explaining major die-offs and understanding the birds’ vulnerabilities to the increasing number of extreme weather events following climate change.
Contact: Tycho Anker-Nilssen