Wigeon (Anas penelope) Science Article 3
Emergence of chironomids started in mid-April, and reached a peak at the end of April and in the beginning of May. Most ‘spring’ chironomids emerged around noon, whereas the majority of chironomids emerging later in the season, appeared at night. In general, there was a positive correlation between the seasonal emergence of chironomids and gleaning frequency by individual Wigeon. Gleaning was observed exclusively on emergent vegetation in the morning and evening. During midday, gleaning occurred most frequently on water surface probably due to the diel emergency and swarming patterns of chironomids. Gleaning was most frequently used by females, which is mainly due to their higher energetic requirements during the breeding seasons. I conclude that the increasing abundance of emerging chironomids in the spring is one important factor affecting time of nesting by Wigeon.
Jacobsen O.W., ARDEA 79 (3): 409-418.