NEST MICROCLIMATE, EGG TEMPERATURE, EGG WATER LOSS, AND EGGSHELL CONDUCTANCE IN CAPE WEAVERS PLOCEUS CAPENSIS

Abstract

Summary Brown, C.R. 1994. Nest microclimate, egg temperature, egg water loss, and eggshell conductance in Cape Weavers Ploceus capensis. Ostrich 65: 26–31. The nest of the Cape Weaver Ploceus capensis is an enclosed, kidney-shaped chamber of closely woven grass. Eggs are incubated by the female alone. Measurements of nest microclimate (temperature and water vapour pressure) were made, and egg water loss and water vapour conductance were measured. Mean nest temperatures and water vapour pressures were generally slightly higher than ambient values and probably related to presence of the female in the nest. Egg temperatures (TE) were relatively constant at night (mean = 36.9°8) when the female incubated continuously. During the da, despite the female's periodic absences from the nest, egg temperature were only slightly lower (35,9°C5 and overall egg temperature averaged 36,4°C. Eggs lost water at a rate of 45 mg day−1, close to that expected for a 3,6 g egg. The nest of Cape Weavers apparently plays little role in the regulation of egg water loss during incubation.