Authors: POLO, V. and CARRASCAL, L. M.
Published: Volume 45(2), December 1998. Pages 201-211.
Language: Spanish
Original Title: Relación entre la condición física invernal y la capacidad de regenerar plumas en el Carbonero Garrapinos (Parus ater)
Keywords: body condition, fluctuating asymmetry, Parus ater, ptilochronology and winter.
Summary:
We have analysed the seasonal variation in the growth rate of tail feathers (right and left fifth rectrix) and its fluctuating asymmetry, and the winter inter-individual variability in body condition (measured as the residual of body mass on tarsus length) and growth of tail feathers (mm/day and its fluctuating asymmetry) in a population of Coal Tits from central Spain (1500 m.s.n.m.). Twenty-two Coal Tits were maintained in a large outdoor aviary (4 x 8x 2 m) where food was provided ad libitum (sunflower seeds and husked peanuts). During the study period (January-March), air temperature at midday was 0.80 ºC (range: -9 to 70 ºC) and there were harsh snowstorms. Tail feathers grew more slowly and more asymmetrically in winter than in summer (Table 1). Fluctuating asymmetry in feather growth rate in winter was more variable than in summer (Fig. 1). Induced rectrices grew in only 64% of the individuals. Those Coal Tits that grew the removed tail feathers had better body condition than those birds that did not regenerate their rectrices (Fig. 2). Nevertheless, winter growth rate of tail feathers was not significantly correlated with residual of body mass in those Coal Tits that regenerated their rectrices. The onset of the growth of induced feathers in winter seemed to require a minimum amount of body reserves, but inter-individual differences in body reserves did not predict inter-individual variations in the growth rate of feathers. Feather growth rate and its fluctuating asymmetry were not significantly correlated in summer, al-though they were positively associated in winter. This result is contrary to the classical prediction
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