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Providing evidence to improve practice

Individual study: Supplementary feeding does not increase measures of reproductive productivity in Wahlberg’s eagles Aquila wahlbergi in South Africa

Published source details

Simmons R.E. (1993) Effects of supplementary food on density-reduced breeding in an African eagle: adaptive restraint or ecological constraint? Ibis, 135, 394-402


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Provide supplementary food for raptors to increase reproductive success Bird Conservation

A replicated controlled trial in subtropical savanna in northeast South Africa in 1989-90 (Simmons 1993) found that Wahlberg’s eagle Aquila wahlbergi pairs that were provided with supplementary food did not breed more often, have significantly larger clutches or eggs and did not lay earlier than control (unfed) pairs (75% of eight fed pairs breeding vs. 76% of 74 control pairs; average of 1 egg/clutch for both six fed and 56 unfed pairs; average egg volume of 76.7 ml for five fed pairs vs. 76.1 ml for five controls). Feeding consisted of approximately 200 g of meat provided daily from when pairs arrived in a territory until seven days after the first egg was laid (between three and six weeks of feeding).