Body condition of five passerines in a forest fragment and associated factors

Daniella Reis Fernandes Teles,Celine De Melo,Thaís Dantas

doi:10.1007/bf03544385

Daniella Reis Fernandes Teles, Celine De Melo + Show 1 more

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https://doi.org/10.1007/bf03544385

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Abstract

Body condition is a qualitative evaluation of an animal and is directly related to its fitness, with the relative mass index (RMI) as a tool for indirect estimation of energy reserves. This study evaluated if the body condition of birds differs between guilds, if it is reflected in levels of subcutaneous fat, and if it is influenced by the weather season and ectoparasite presence. The RMI was calculated for Antilophia galeata (frugivorous), Arremon flavirostris, Eucometis penicillata (omnivorous), Basileuterus culicivorus, and Myiothlypis leucophrys (insectivorous). It varied among guilds (F2, 295 = 187.92; P < 0.05), with insectivorous species having negative values. The RMI varied between the wet and dry seasons only for A. galeata (F1, 1 = 7.28; P < 0.05) but remained positive throughout the year in omnivorous species. The RMI did not vary with the presence/absence of ectoparasites nor among the different levels of subcutaneous fat, which were predominantly low. The negative RMI of insectivores and its variation in frugivorous between seasons suggest that the body condition is influenced by the type of diet and the availability of food resources, indicating that birds with a specialized diet may be more sensitive to environmental variations that result in fluctuations in the food supply.

Highlights

Positive values of relative mass index (RMI) in both seasons were detected for E. penicillata, followed by A. galeata and A. flavirostris (Table 1)
A. galeata presented a difference in RMI between seasons (F1, 1 = 7.28; P < 0.05; Table 2), with values higher in the wet season (0.086 ± 0.047) than in the dry season (0.064 ± 0.041) (Table 1)
The species belonging to the Parulidae family, which are strictly insectivorous, had a negative RMI in both seasons (Table 1), presenting a body condition inferior to the other species analyzed

Summary

Introduction

Studies of fauna that assess the individual physical condition by means of physiological indicators, such as body condition and hormonal status, may be advantageous in obtaining responses from the bird population based on landscape changes (Johnson et al 1985, Janin et al 2011), evaluation of environments in various degrees of conservation (Costa & Macedo 2005), and the conditions of these environments (Møller & Erritzøe 2003, Costa & Macedo 2005). According to Johnson et al (1985), to assess fat reserves, the options are direct extraction of lipids, a method considered to be the most accurate and costly; measurement of the dry biomass through water extraction; measurement of fat deposits through animal dissection; and the RMI This index is obtained through the mass of individuals caught in the field associated with a morphometric measurement (Jakob et al 1996, García-Berthou 2001, Schulte-Hostedde et al 2001, Velando & Alonso-Alvarez 2003, Ardia 2005, Gosler 2005, Schulte-Hostedde et al 2005, Serrano et al 2008, Peig & Green 2010)

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