Section 6
Chapter 5,134

Development of homeo thermy in the diving petrels pelecanoides urinatrix exsul and pelecanoides georgicus and the antarctic prion pachyptila desolata

Ricklefs, R.E.; Roby, D.D.

Comparative Biochemistry and Physiology A 75(2): 307-311


ISSN/ISBN: 1095-6433
Accession: 005133792

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Body temperatures of south Georgia diving petrel (P. georgicus) chicks increased from .apprx. 37.5.degree. C at hatching to between 38.5.degree. and 39.degree. C within 2 wk. Temperatures of common diving petrel P. u. exsul chicks averaged 38.8.degree. C after 2 wk of age. Burrow temperatures varied between 5.degree. and 10.degree. C. Measurements of O2 consumption and body temperature indicated that chicks achieve effective endothermy at 5.degree. C after 9 days in P. u. exsul, 5-6 days in P. georgicus, and 0 days in the Antarctic prion (P. desolata). The maximum mass-specific, cold-induced O2 consumption of small chicks that could be measured (5-6 cc O2/g per h) was achieved at 5-6 days in P. u. exsul, 3 days in P. georgicus, and 0 days in P. desolata. Mass-specific thermal conductance decreased with age and body size in all 3 spp., but was highest in P. u. exsul and lowest in P. desolata. Conductance was similar at the age of effective endothermy in all 3 spp. (3 J/g per h per.degree. C). The period required for the development of endothermy is related to age-specific changes in both conductance and capacity for heat production and closely parallels the length of the brooding period. The length of the period of thermal dependence of the chick is related to the distance between feeding areas and the nesting site.

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