Foraging behaviour and daily time budget of Scaly-sided Merganser Mergus squamatus breeding on the Iman River, Russia

D Solovieva
Daily tim e budget (DTB), foraging behaviour and the human affect on DTB of breeding S caly-sided M erganser w ere studied on the upper Iman River, P rim orye, Russia. Daytim e averaged 14.8 hours in the period from a rriva l on the breeding grounds until m id-incubation. The Scaly-sided M erganser is a daytim e feeder, and feeding increased p rio r to night [F7 i36=2.34, P<0.03). Detailed DTB was obtained for entire breeding pe ri­ od in m ales and fo r la yin g and in cubating pe rio d s in
more » ... m ales. Scaly-sided M ergansers em ployed two different feeding techniques: div­ ing fo r fish after riv e r ice break up and non-diving foraging before ice break up. Durations of feeding bout, diving bout, daytim e sleep, dive and in te r-d ive acts w ere m easured in both sexes. Disturbance by people required 0.11 hours additional fligh t during an average day. Incubating fem ales have one o r two non-active periods per day, w hich m ainly occurred around the noon.