Individual study: Supplementary feeding increases fledging weight, late growth and peak weights in Atlantic puffin Fratercula arctica chicks
Cook M.I. & Hamer K.C. (1997) Effects of supplementary feeding on provisioning and growth rates of nestling puffins Fratercula arctica: evidence for regulation of growth. Journal of Avian Biology, 28, 56-62
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Provide supplementary food for auks to increase reproductive success
A replicated, controlled trial on the Isle of May, eastern Scotland, in June and July 1995 (Cook & Hamer 1997), found that Atlantic puffin Fratercula arctica chicks attained greater peak and fledging weights if they were fed daily (starting at eight days old and continued until fledging) with 25 g of sardines Sardina pilchardus, compared with control (unfed) chicks (peak weight of 319 g and fledging weight of 287 g for fed chicks, n = 22 vs. 305 g and 271 g for controls, n = 22). There was no difference in growth rates between treatments until chicks were 32 days old and no differences between growth rates of wing, head or tarsi. Fed chicks reached peak weights later than controls (peak weight at 35 days for fed chicks vs. 32 days for controls) but fledged at the same age (41 days old). Fed chicks were supplied with food by their parents significantly less often than control chicks. The authors suggest that additional weight was due to significantly less feeding by parents shortly before fledging, meaning that supplementary food provided a higher proportion of food received.