The effects of long-term captivity on the metabolic parameters of a small Afrotropical bird

Abstract

The few within-species studies on the effects of long-term captivity on avian physiological variables have small samples sizes and contradictory results. Nevertheless, many physiological studies make use of long-term captive birds, assuming the results will be applicable to wild populations. Here we investigated the effects of long-term captivity on a variety of physiological measurements in a relatively small (~12 g) southern African endemic bird, the Cape white-eye (Zosterops virens). Whole animal basal metabolic rate (BMR) and body mass (Mb) were influenced more by long-term captivity than by season, while mass-specific BMR, standard and basal whole animal and mass-specific evaporative water loss (EWL), and respiratory quotient (RQ), were all affected primarily by season, with long-term captivity having less of an effect. We therefore caution that whole animal BMR and Mb of long-term captive birds should not be used as representative of wild populations, and that the origin of study birds should be considered when comparing EWL and RQ of wild and long-term captive birds.

The potential effects of climate change-associated temperature increases on the metabolic rate of a small Afrotropical bird

“…However, long-term captivity in outdoor aviaries is linked to a significant increase in whole-animal BMR of Cape white-eyes (Thompson et al, 2015a) and so we can assume that RMR values for wild Cape white-eyes would be lower than those presented in this study. Indeed, the ecological relevance of laboratory studies has been questioned (Chown et al, 2010), so ideally, this experiment should be repeated with birds housed in large outdoor temperature-controlled aviaries.…”

“…) were recorded every 5 s. An interrupted sampling regime was used (Thompson et al, 2015a), beginning with a baseline measurement for 6 min, and then four birds for 6 min each. This sequence was repeated so that each bird was measured twice (for 12 min in total) per hour.…”