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Body condition of Passeriformes (Aves) in a forest fragment and associated factors

Daniella Reis Fernandes Teles, Thaís Dantas, Celine de Melo

Abstract


Body condition is a qualitative evaluation of an animal and is directly related to its fitness, with the Relative Mass Index (IMR) being a tool used for an indirect estimate of energy reserves. This study evaluated if the body condition of birds differs between guilds, if this is reflected in levels of subcutaneous fat and if it is influenced by the weather season and ectoparasite presence. The IMR was calculated for Antilophia galeata, Arremon flavirostris, Basileuterus culicivorus, Myiothlypis leucophrys and Eucometis penicillata. The IMR varied between guilds (F 2,295 = 187.917; P < 0.05) with the insectivorous species having negative values. The IMR varied between the wet and dry seasons only for A. galeata, which is frugivorous (F 1,1 = 7.276; P < 0.05), but remained positive throughout the year, as well as in omnivorous species. The IMR did not vary with the presence/absence of ectoparasites nor between the different levels of subcutaneous fat, which were predominantly low. The negative IMR of insectivores and variation of same in frugivorous between seasons suggest that the body condition seems to be influenced by the type of diet and the availability of resource, indicating that birds with a specialized diet may be more sensitive to environmental variations, which result in fluctuations in the food supply.

Key-Words: Cerrado; climate season; feed guild; subcutaneous fat; tick.

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