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Providing evidence to improve practice

Individual study: Supplementary feeding can increase reproductive success in cactus wrens Campylorhynchus brunneicapillus at a desert site in Arizona, USA

Published source details

Simons L.S. & Martin T.E. (1990) Food Limitation of Avian Reproduction: An Experiment with the Cactus Wren. Ecology, 71, 869-876


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 randomised, replicated and controlled paired study in a Sonoran desert site in Arizona, USA, in the breeding seasons of 1986 and 1987 (Simons & Martin 1990) found that 28 cactus wren Campylorhynchus brunneicapillus broods were 10.5-20.0 g heavier from territories provided with supplementary food, compared with control broods. Parents from fed territories were also more likely to have second clutches than controls (12 of 14 fed pairs attempted second broods vs. seven of 14 control pairs). Fed nestlings were also larger and had higher post-fledging survival rates in 1986 but not 1987 (1986: 14 pairs, linear measurements 1.0-2.7 mm larger than controls, 15 fed fledglings surviving for four to six weeks after fledging vs. seven control fledglings; 1987: 14 pairs, linear measurements 0.2-0.6 mm larger than controls, 19 fed fledglings surviving vs. 16 controls). The authors suggest that differences between years were due to higher levels of natural food occurring in 1987. Supplementary food consisted of 35 g of mealworm Tenebrio molitor larvae and noctuid moth caterpillars supplied every other day from one or two days after hatching until nestlings fledged (approximately 20 days later) and comprised 75% (1986) and 80% (1987) of food delivered to nests.