Thermal Responses of Late Embryos and Hatchlings of the Sooty Tern
Date
1994Author
Mathiu, P. Mbaabu
Dawson, William R
Whittow, G. Causey
Type
ArticleLanguage
enMetadata
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Oxygen consumption (VO<sub>2</sub>) and body temperature (T<sub>b</sub>) of young Sooty Terns (Sterna fuscata) were measured during late incubation and in the first 24 hr after hatching at ambient temperatures (T<sub>a</sub>) between 28° and 38°C and between 15° and 43°C, respectively. Evaporative cooling by hatchlings at T<sub>a</sub> of 36°-43°C was also measured. Significant increases in embryonic metabolic level occurred between external and internal pipping and between internal pipping and establishment of a pip hole. However, despite the improving access to oxygen produced by these events, VO<sub>2</sub> and T<sub>b</sub> both varied directly with T<sub>a</sub> in an ectothermic pattern throughout the final stages of incubation. A capacity for sustained endothermy only became apparent in hatchlings. Their VO<sub>2</sub> varied inversely with T<sub>a</sub> between 27.5° and 36°C to an extent indicating a modest capacity for regulatory thermogenesis. This served to maintain T<sub>b</sub> above 35°C in this range of T<sub>a</sub>. The apparent abruptness of the appearance of this regulatory capacity after hatching suggests that emergence from the physical confinement of the egg could be an important proximate factor in the establishment of endothermy in this semi-precocial species. Hatchling Sooty Terns underwent a progressive fall in T<sub>b</sub> with declining T<sub>a</sub> below 27.5°C. On the other hand, they appeared quite proficient at evaporative cooling with increasing T<sub>a</sub> between 36° and 43°C.
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http://www.jstor.org/discover/10.2307/1369314?searchUri=%2Faction%2FdoBasicSearch%3FQuery%3DP.%2BMbaabu%2BMathiu%26filter%3D%26Search%3DSearch%26wc%3Don&Search=yes&searchText=P.&searchText=Mathiu&searchText=Mbaabu&uid=2134&uid=2&uid=70&uid=4&sid=21102095736253http://erepository.uonbi.ac.ke:8080/xmlui/handle/123456789/32015