The condition of nestling House Sparrows Passer domesticus in relation to diet composition and the total amount of food consumed

Abstract

Capsule A higher animal component in the diet and a greater amount of food result in better condition. Aims To investigate the relative importance of different food types to nestling House Sparrows. Methods Faecal sac samples (n = 206) from 106 nestlings of 31 broods were analyzed in 2 breeding seasons (2008, 2009). The nests were in a nestbox colony on a farm in south Bohemia, Czech Republic. Results Faecal sacs contained 362 identifiable animal food objects belonging to 5 arthropod orders. The nestlings were fed primarily on beetles (mainly Scarabeidae) and Diptera (mainly muscids and tipulids). The total amount of food found in the faecal samples increased with nestling age. This increase was because of an increase in the total mass of plant material; the total mass of animal component did not change with nestling age. The total amount of food, and the mass of animal component in the diet of older nestlings were all positively related to nestling body condition. Conclusions To compensate for the increasing demands of older nestlings, the parents increased the mass of plant material in the nestlings' diet. This might have been caused by an upper limit to their ability to catch invertebrate prey, or by the growing nestlings' preference for plant material. The effect of food amount and animal component in nestling diet on their condition stressed the importance of arthropods for the breeding success of House Sparrows. © 2012 Copyright British Trust for Ornithology.