Jenni-Eiermann, S., L. Jenni & T. Piersma (2002)

    Temporal uncoupling of thyroid hormones in Red Knots: T3 peaks in cold weather, T4 during molt.

    Further information

    J. Ornithol. 143: 331–340



    Seasonal variation in plasma concentrations of the two thyroid hormones T3 (triiodthyronine) and T4 (thyroxine) was studied in captive flocks of two subspecies of Red Knot: Calidris canutus canutus, wintering in tropical West Africa and C.c. islandica, wintering in temperate (northwest) Europe. For more than 1.5 years in outdoor aviaries both groups maintained subspecies- specific annual cycles of body mass and moult. Thyroid hormones also showed annual cyclicity. Plasma T3 levels followed an unimodal pattern, with high values during the cold season in both subspecies. This is consistent with published evidence that T3 may be involved in the adjustment of metabolic rate to ambient cost levels. Plasma T4 levels were positively correlated with moult intensity among individuals within the two groups, which corroborates published evidence that T4 plays a role in the regulation of moult.