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Providing evidence to improve practice

Individual study: Supplementary feeding enhances weight gain of nestling Atlantic puffins Fratercula arctica on St. Kilda and the Isle of May, Scotland

Published source details

Harris M.P. (1978) Supplementary feeding of young puffins, Fratercula arctica. Journal of Animal Ecology, 47, 15-23


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 auks to increase reproductive success Bird Conservation

A controlled, replicated study on St. Kilda, western Scotland, in 1975 (Harris 1978), found that Atlantic puffin Fratercula arctica chicks fledged at significantly higher weights if they were provided daily with 50 g of sprats Sprattus sprattus, compared to control chicks (average weight of 316 g for 11 fed chicks vs. 301 g for 37 controls). Five chicks removed from burrows and fed sprats ad libitum were even heavier (365.g) while three unfed chicks with a single parent were lighter (240 g). All removed chicks and fed chicks fledged, 37 of 39 controls fledged and three of six single-parent chicks fledged. There was no difference in fledging age between fed and control chicks (40 days), but single-parent chicks took longer to fledge (45 days). A parallel study on the Isle of May (eastern Scotland) found smaller differences between treatments (removed: 367 g for six chicks; fed: 344 g for ten; controls: 331 g for 70; single-parent: 303 g for four), suggesting that St. Kilda puffins are to some degree food limited.