Effect of experimentally altered food abundance on fat reserves of wintering birds

Published source details Rogers C.M. & Heath-Coss R. (2003) Effect of experimentally altered food abundance on fat reserves of wintering birds. Journal of Animal Ecology, 5, 822-830.
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This study is summarised as evidence for the following.

	Action	Category
	Can supplementary feeding increase predation or parasitism? Action Link
	Provide supplementary food for songbirds to increase adult survival Action Link

Can supplementary feeding increase predation or parasitism?

A replicated, controlled study at two pairs of mixed habitat sites in Kansas, USA, in the winters 2000-1 and 2001-2 (Rogers & Heath-Coss 2003) found that predation rates on seven species of songbird by Cooper’s hawk Accipiter cooperi and sharp-shinned hawk A. striatus were no higher in an area supplied with supplementary food, compared with control (unfed) sites (two attacks in fed sites vs. no attacks in control sites). Supplementary feeding ran from early December until early March and consisted of four sunflower seed feeders and a 6 x 3 m area beneath them sprinkled with mixed seed. The species studied were dark-eyed junco Junco hyemalis, Harris’s sparrow Zonotrichia querula, song sparrow Melospiza melodia, American tree sparrow Spizella arborea, northern cardinal Cardinalis cardinalis, black-capped chickadee Parus atricapillus (also known as Poecile atricapillus) and tufted titmouse Parus bicolor. The effects of feeding on songbird body condition are discussed in ‘Provide supplementary food to increase adult survival’.
Provide supplementary food for songbirds to increase adult survival

A replicated, controlled study at two pairs of mixed habitat sites in Kansas, USA, in the winters 2000-1 and 2001-2 (Rogers & Heath-Cross 2003) found that seven songbird species had higher levels of visible subcutaneous fat in areas supplied with supplementary food, compared with those in control (unfed) areas. Most differences were significant in both years and both pairs of sites, but differences were always small. Body mass relative to size showed a similar trend, but the differences were not significant. Supplementary feeding ran from early December until early March and consisted of four sunflower seed feeders and a 6 x 3 m area beneath them sprinkled with mixed seed. The species studied were dark-eyed junco Junco hyemalis, Harris’s sparrow Zonotrichia querula, song sparrow Melospiza melodia, American tree sparrow Spizella arborea, northern cardinal Cardinalis cardinalis, black-capped chickadee Parus atricapillus (also known as Poecile atricapillus) and tufted titmouse Parus bicolor. The effects of feeding on predation rates are discussed in ‘Can supplementary feeding increase predation or parasitism?’.