title: Thyroid hormones correlate with basal metabolic rate but not field metabolic rate in a wild bird species.
abstract: Thyroid hormones (TH) are known to stimulate in vitro oxygen consumption of tissues in mammals and birds. Hence, in many laboratory studies a positive relationship between TH concentrations and basal metabolic rate (BMR) has been demonstrated whereas evidence from species in the wild is scarce. Even though basal and field metabolic rates (FMR) are often thought to be intrinsically linked it is still unknown whether a relationship between TH and FMR exists. Here we determine the relationship between the primary thyroid hormone triiodothyronine (T3) with both BMR and FMR in a wild bird species, the black-legged kittiwake (Rissa tridactyla). As predicted we found a strong and positive relationship between plasma concentrations of T3 and both BMR and mass-independent BMR with coefficients of determination ranging from 0.36 to 0.60. In contrast there was no association of T3 levels with either whole-body or mass-independent FMR (R(2) =0.06 and 0.02, respectively). In accordance with in vitro studies our data suggests that TH play an important role in modulating BMR and may serve as a proxy for basal metabolism in wild birds. However, the lack of a relationship between TH and FMR indicates that levels of physical activity in kittiwakes are largely independent of TH concentrations and support recent studies that cast doubt on a direct linkage between BMR and FMR.
authors: Norwegian Polar Institute, Tromsø, Norway. jorg.welcker@npolar.no
authors: Jorg
authors: J
authors: Welcker
authors: Olivier
authors: O
authors: Chastel
authors: Geir W
authors: GW
authors: Gabrielsen
authors: Jerome
authors: J
authors: Guillaumin
authors: Alexander S
authors: AS
authors: Kitaysky
authors: John R
authors: JR
authors: Speakman
authors: Yann
authors: Y
authors: Tremblay
authors: Claus
authors: C
authors: Bech
mesh_terms: D000818:Animals; D000835:Animals, Wild / Q000097:blood / Q000378:metabolism*; D001481:Basal Metabolism / Q000502:physiology*; D001835:Body Weight; D046091:Charadriiformes / Q000097:blood / Q000378:metabolism*; D005260:Female; D008297:Male; D009664:Norway; D013963:Thyroid Hormones / Q000378:metabolism*; D014284:Triiodothyronine / Q000097:blood
chemical_list: D013963:Thyroid Hormones; D014284:Triiodothyronine