Post-hatching thyroid development and body growth in precocial vs altricial birds

1. 1. Thyroid growth, thyroid function and body growth are markedly different in developing precocial Japanese quail and altricial Ring doves despite comparability in incubation period, hatchling size, adult body weight and adult serum thyroid hormone concentrations. 2. 2. In quail thyroid activity is high during the perinatal period, declines shortly after hatching, then gradually attains adult function. 3. 3. In contrast, in doves, there is no perinatal peak of thyroid activity. Thyroid function is low at hatching and increases steadily during the first week. Serum hormone concentrations vary around a mean similar to that of adults during the remainder of the nestling and fledgling periods.