Body Size and Timing of Fledging of Atlantic Puffins in the Faeroes and Northwest Norway

Abstract

Abstract We studied the way, timing and diurnal rhythm of young Atlantic Puffins (Fratercula arctica) leaving colonies in NW Norway and Faeroes. The colonies differed in nesting habitat and predatory pressure. Both adult and young Puffins from Bleiksoy were significantly larger and heavier than those from Nolsoy. Young birds left the Bleiksoy colony about ten days later in the season, but considerably earlier during the night (22.00-04.00 h; peak: 00.00-01.00 h) than those on Nolsoy (24.00-0600 h; peak: 02.00-03.00 h). The fledging period was more synchronized on Bleiksoy, both within the season and on particular nights. Body mass and size of young puffins leaving the colony tended to decrease through the fledging period. Well-developed young birds from sloping parts of the Bleik colony flew down to the sea, while those from the lower-lying, flatter parts of the colony and those in poor condition walked to the sea. Fledglings which left on the wing reached the sea about one hour earlier and could fly beyo...