A method of food supplementation for ground-foraging insectivorous songbirds

Abstract

Food supplementation can be an important experimental technique in studies of avian reproductive ecology, energetics, and parental care. We developed a method of food supplementation suitable for ground-foraging insectivorous passerines and tested it on Ovenbird (Seiurus aurocapilla) and Wood Thrushes (Hylocichla mustelina). We provided mealworms at feeding stations made of plastic transparency film covered with a thin layer of green moss. Feeding stations were placed on the ground or on logs or boulders in the vicinity of nests. Direct and indirect evidence suggested that 92% of breeding Ovenbirds and 79% of breeding Wood Thrushes used supplemental food. The impact of non-target consumers was not significant: they were observed eating mealworms at approximately one-third of our food-supplemented nests. However, diurnal non-target consumers were only detected on a single occasion for each species, and nocturnal consumers fed on small amounts of mealworms left after daytime feeding experiments. This method proved very effective for Ovenbirds and Wood Thrushes, and it may be applicable to other ground-foraging insectivorous passerines.