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Providing evidence to improve practice

Individual study: Supplementary feeding reduces brood sizes for blue and great tits

Published source details

Harrison T.J.E., Smith J.A., Martin G.R. & Chamberlain D.E. (2010) Does food supplementation really enhance productivity of breeding birds? Oecologia, 164, 311-320


This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.

Provide supplementary food for songbirds to increase reproductive success Bird Conservation

A replicated, controlled study over 3 breeding seasons in 2006-2008 in 3 treatment blocks (2 experimental and 1 control; 96 nestboxes/block) of broadleaf, deciduous woodland in Worcestershire, UK (Harrison et al. 2010), found that blue tits Parus caeruleus (also known as Cyanistus caeruleus) and great tits Parus major began laying significantly earlier (by averages of two and three days respectively), had reduced clutch size (mean reduction: 0.4 and 0.7 eggs), shortened incubation periods (mean reduction: 0.9 and 0.7 days), lowered hatching success (in blue tits only: mean reduction: 1.4%) and reduced brood size (mean reduction: 0.6 and 0.5 chicks for blue and great tits respectively). Treatment blocks were separated by a 90 m buffer strip. In each year, one treatment block received no supplementary food and two treatment blocks received peanut cake (comprising 50% ground peanuts and 50% beef tallow). Treatments were rotated amongst plots.