Home – Home – Jornals – Contemporary Problems of Ecology 2011 number 4

Results of comparative analysis of selectivity patterns of food items for two ecologically close hollow-nesting birds - red-breasted flycatcher Ficedula parva (Muscicapidae) and Siberian tit Parus cinctus (Paridae) according to the way of catching, the place of foraging and the daily activity in nestling feeding are considered. The main diet of nestlings studied consists of spiders and insects; the proportion of these taxons is almost identical for both species. So, the share of spiders in the diet of red-breasted flycatcher is 37 %, insects 59 % (totally 424 food items), and for Siberian tit it is 36.9 and 61.6 % (totally 130), respectively. However, the first species catches predominantly flying imago forms of insects (32.6 %), and the second one - non-flying, larval forms (37.7 %). The observed selectivity of these two bird species reflects the difference in the ways and places of foraging. The identified selectivity of victims testifies about the difference in their way and place of food catching. Daily duration of nestling feeding is 17-18 h for red-breasted flycatcher and 16-17 h for Siberian tit. Daily frequency of nestling feedings depends on weather and varies in different ways. In red-breasted flycatcher, it varies from 209 to 656 times in warm and cold weather, while in Siberian tit from 182 to 151, respectively. Apparently relatively low daily activity of nestling feeding and absence of strong fluctuations depending on weather conditions in Siberian tit relate to low need of its nestlings in food resources and condition larger adaptation of this species to acute fluctuations of environmental temperature.