Ardea
Official journal of the Netherlands Ornithologists' Union

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Redfern C.P.F., Douglas G.W. & Halliday T.A. (2002) Intestine length and mass relative to fat in migrating Redwings Turdus iliacus. ARDEA 90 (2): 285-292
Redwings which died by flying into a lighthouse off North Wales, UK, while on migration were used to examine the relationship between fat levels and intestine size. The weight of claviculo-coracoid fat was used as a measure of relative fat levels. Both intestine length and claviculo-coracoid fat mass correlated with wing length, a measure of body size. Lipid-extracted dry mass of the intestine did not correlate with wing length or with intestine length; dry mass and length were therefore independent measures of intestine size. Claviculo-coracoid fat mass correlated with intestinal length in first-year females which, for this group, explained 25% of the variance in fat mass independently of body size. For all birds, claviculo-coracoid fat mass also correlated with intestine lipid-extracted dry mass, explaining 10% of variance in claviculo-coracoid fat mass independently of body size. Intestine dry mass may be a factor determining the extent of fat accumulation in individual birds, or may be correlated with fat losses during flight. However, since claviculo-coracoid fat mass correlated with intestine length in first-year female Redwings, we speculate that diet may vary according to experience and dominance interactions within feeding flocks


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