Vocal solicitation of heat as an integral component of the developing thermoregulatory system in young domestic chickens

Abstract

Young domestic chickens (Gallus gallus) were able to regulate their body temperature in a laboratory setting, where vocalizations triggered a period of rewarming (35 °C) in an otherwise cold environment. Vocal solicitation of a rewarming period functioned in an analogous manner to the parental brooding response to a vocalizing chick. The number of vocally generated rewarming bouts increased if the cold-challenge temperature was decreased from 20 to 5 °C. The body temperature and ambient temperature maintained during vocal regulation were not significantly affected by the cold-challenge temperature. Thermoregulatory reliance on vocally induced rewarming bouts decreased with age as endothermic capability and the ability to retain heat improved. This decreased reliance on vocally induced heat inputs matches the pattern of decline of parental brooding seen in chicks reared in a natural setting. Body temperature at both cold-challenge temperatures increased with age, while the preferred ambient temperature decreased with age. This pattern is also found in the young of many birds species tested in spatial thermal gradients. Vocal solicitation of heat thus appears to form an integral and finely tuned part of the overall thermoregulatory system of these young precocial birds.