Supplementary food improves the nutritional condition of wintering woodland birds: evidence from ptilochronology

Published source details Grubb T.C. & Cimprich D.A. (1990) Supplementary food improves the nutritional condition of wintering woodland birds: evidence from ptilochronology. Ornis Scandinavica, 21, 277-281.
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This study is summarised as evidence for the following.

	Action	Category
	Provide supplementary food for woodpeckers to increase adult survival Action Link
	Provide supplementary food for songbirds to increase adult survival Action Link

Provide supplementary food for woodpeckers to increase adult survival

A replicated, controlled study in deciduous forests in Ohio, USA, in the winter of 1988-9 (Grubb & Cimprich 1990) found that 12 female downy woodpeckers Picoides pubescens grew longer feathers and grew them faster (a proxy for nutritional condition) when supplied with sunflower seeds and suet in excess, compared to six unfed control females. There were no such differences in eight fed and nine control male woodpeckers. The impact on three songbird species is discussed in ‘Provide supplementary food to increase adult survival – Songbirds’.
Provide supplementary food for songbirds to increase adult survival

A replicated, controlled study in ten deciduous forest plots in Ohio, USA, in the winter of 1988-9 (Grubb & Cimprich 1990) found that three species of songbirds grew longer replacement feathers when provided with sunflower seeds and suet in excess, compared to control birds which were not fed. However, most of these differences were not significant, with only tufted titmice Baeolophus bicolor (formerly Parus bicolor) consistently showing significant differences across ages and sexes. Replacement feathers appeared to grow faster (a proxy for nutritional condition) in titmice and white-breasted nuthatches Sitta carolinensis of all age classes and both sexes. Immature and male Carolina chickadees Parus carolinensis also showed more rapid growth when fed, the sample size for female chickadees was too small for comparison and there was no significant difference between fed and unfed adult chickadees. When corrected for body size, differences for male titmice and male nuthatches became non-significant. Sample sizes were: 13 male chickadees, five females, 15 adults and 28 immatures; six male titmice, 14 females, 12 adults and 17 immatures; 16 male nuthatches, ten females. The impact of feeding on downy woodpeckers Picoides pubescens is discussed in ‘Provide supplementary food to increase adult survival – Woodpeckers’.