The Early Development of Thermoregulation in Birds

• DOI: 10.1086/physzool.64.6.30158220
• Publication Date: 2016-01-07T16:06:35Z
• Authors: G. Causey Whittow; Hiroshi Tazawa
• Keywords: Precocial; Altricial; Hatchling; Homeothermy; Yolk

There is evidence for incipient thermogenesis in the embryos of precocial species birds during later stages incubation. In ovo, nascent thermoregulation limited by (1) high thermal conductance egg and embryonic tissues, (2) rate at which oxygen can diffuse into through shell chorioallantoic membrane ("oxygen-conductance limited"), (3) degree development thyroid gland metabolic capacity embryo ("power limited"). with a semiprecocial mode development, hatching appears to be climactic event thermoregulation. contrast, altricial are mercy ambient temperature ("Arrhenius limited") even after hatching, they never experience an oxygen-conductance limitation. Thus, there great disparity thermoregulatory competence hatchlings varying from poikilotherm homeotherm. Consequently, entirely posthatching event, whereas component process subject several extraneous limitations, notably functional pore structure eggshell, membrane.