*ost-fledging migration of common murres Una aalge in the Baltic Sea: management implications

• Main Authors: Chof Ouson, Thord Fransson, Kjell Larsson
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Common Murre; Uria aalge; uria
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.494.8392; http://www.balticseabird.com/pdf/Post-fledging migration.pdf

In ihis study of common murre Uria aalge chicks, at Slora Karlso in the Baltic Sea (Sweden), we used two data sets to investigate the post-fledging migration to learn more on potential threats from human activities. Firstly, we radio tracked 12 chicks on average 5.1 h during their first night at sea, after jumping from the breeding cliffs in early July. Their average speed was 1,9 km h ~ ' and all chicks swam in a similar direction (SW) with a mean bearing of 235°. By searching an area of ca 400 km^ further off the island between two and six days after the radio tracking, we concluded that they did not stop, even temporarily, within 40 km off the island, but had continued the swimming migration. Our second data set was made up by 400 recoveries of ringed chicks. Only those recovered within eight months after fledging (until February) were included. Two birds recovered al ihe Polish coast in the beginning of August had moved on average 10.7 and 12.3 km day ' (i.e. 0.45-0.51 km h ~ '). In August, all chicks, except one, were found south of Gotland> 70 km away. The average distance to the recovery sites in.August was 253.5 km (n = 11). The pattern of distribution of birds reported in September. October and during the