Uniformity of diet composition of Brown Skua chicks at different ages and between siblings

GRAÑA GRILLI, M.; MARTI, L.J.; MONTALTI, D.

ARARAJUBA: REVISTA BRASILEIRA DE ORNITOLOGIA

SOC BRASILEIRA ORNITOLOGIA

Lugar: Pelotas, RS; Año: 2014 vol. 22 p. 265 - 269

0103-5657

The diet of chicks may change according to their growth and also vary between siblings due to their competitive relationship. Diet composition of 81 Brown Skua (Stercorarius antarcticus lonnbergi) chicks was analysed from regurgitated stomach contents to determine changes in diet composition related to chick age and differences between siblings. Fifty-nine of the samples belonged to chicks whose age was estimated by applying culmen measurement to a regression function. The remaining 22 samples belonged to 11 sibling pairs whose stomach contents were simultaneously sampled. The diet consisted mostly of penguin soft tissue. Marine resources were a minor part of the diet of chicks, appearing in the third week of their life. The qualitative composition of the stomach content of siblings was similar in most cases, but the mass of regurgitates differed between siblings (1.3-90.0% = 0.5-9 g), which suggest the potential existence of aggressive food monopolization by one sibling, an issue to be elucidated with further research.