Effects of Diet Quality on the Nestling Growth of a Wild Insectivorous Passerine, the House Martin Delichon urbica

Abstract

Many studies have shown environmental effects on the growth and body size of wild birds. Most investigations have centred on the role of nestling nutrition in these effects. However, few of these studies have investigated the role of diet quality in the growth of wild birds. In this study I investigate the effect of altering nestling diet quality on the growth of a hirundine, the house martin. The quality of the diet fed to nestling house martins was reduced through direct fat feeding. This resulted in a diet of insects and fat which satisfied energy demand while providing fewer nutrients than the usual wholly insect diet. Effects of fat feeding were monitored by recording parental visits, by collecting the faecal output of broods and by measuring nestling growth