SITE DESCRIPTION

Ammarnäs is located in a mountainous region of Swedish Lappland roughly 100 km south of the Arctic Circle.  The predominant forest type in the area is birch forest, but there is also some coniferous forest. The first bluethroats usually arrive from May 16 – 20, while the median arrival date is May 28. In mid-May, the day-time temperature is usually 0-5 C and there is often still snow covering the ground.

RESEARCH ACTIVITY We measured the song and song-flight rates of male Bluethroats as they arrived on their breeding grounds during May 2001 and 2002. Bluethroats were captured and color-marked during mist-netting operations of researchers from Lünd University. We also monitored nests of color-marked Bluethroats.

JEFF MOLLENHAUER

Many migratory birds are known to arrive on their breeding grounds with surplus fat stores. Several hypotheses have been developed to explain the possible advantages of having surplus fat stores upon arrival at the breeding grounds. Jeff tested the time constraint hypothesis, which states that birds breeding at high latitudes (short breeding season) are able to use fat stores to offset time constraints. For example, a fat male may be able to spend more time singing because he does not need to spend as much time foraging. Jeff found that fat was positively related to the percentage of time males spent singing and performing song-flight. These results support the time constraint hypothesis.

The University of Southern Mississippi. Last modified: 24 February, 2007 . Questions and Comments?
URL: http://www.usm.edu/mbrg/Ammarnas.html
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