Thermoregulation and muscular development in cold exposed willow ptarmigan chicks (Lagopus lagopus L.)

Adaptations to polar life in mammals and birds

“…The ptarmigan chick and reindeer and muskoxen calves are typical examples. The ptarmigan chicks hatch with an effective down plumage and are able to travel large distances even on their first day, and they have a substantial thermogenic capacity, which is based primarily on shivering in their breast muscle (Aulie and Steen, 1976). Even so, the chicks have to return to the mother for brooding when their body temperature approaches 35°C (Theberge and West, 1973); they apparently use their thermogenic capacity only to restrict their cooling rate so that the duration of their feeding excursions becomes less dependent on ambient temperature (Jørgensen and Blix, 1988).…”

Adaptations to polar life in mammals and birds

“…The ptarmigan chick and reindeer and muskoxen calves are typical examples. The ptarmigan chicks hatch with an effective down plumage and are able to travel large distances even on their first day, and they have a substantial thermogenic capacity, which is based primarily on shivering in their breast muscle (Aulie and Steen, 1976). Even so, the chicks have to return to the mother for brooding when their body temperature approaches 35°C (Theberge and West, 1973); they apparently use their thermogenic capacity only to restrict their cooling rate so that the duration of their feeding excursions becomes less dependent on ambient temperature (Jørgensen and Blix, 1988).…”

Development of temperature regulation in the grey partridge Perdix perdix

“…They usually comprise a greater proportion of body mass than pectoral muscles in precocial birds at hatching (e.g. Aulie 1976c, Ricklefs 1979. Later, the mass of the pectoral muscles cert ainly exceeds that of the leg muscles together with their increased capacity for heat produ ction.…”

Homeothermy in neonatal chicks exposed to low environmental temperature with or without intracerebroventricular administration of corticotropin‐releasing factor

“…The ability of chicks to regulate body temperature during the post‐hatching period increases in an age‐dependent manner and birds become completely homeothermic by the age of 10 days [19]. During development, birds increase their capacity to regulate body temperature, as the size and maturity of the skeletal muscles and other organs that generate heat in response to decreasing body temperature increase [20,21]. The development of thermoregulation is also promoted by a decrease in the thermal conductance of the chick resulting from increased size and insulation of the body [22].…”

Adaptations to polar life in mammals and birds

“…The ptarmigan chick and reindeer and muskoxen calves are typical examples. The ptarmigan chicks hatch with an effective down plumage and are able to travel large distances even on their first day, and they have a substantial thermogenic capacity, which is based primarily on shivering in their breast muscle (Aulie and Steen, 1976). Even so, the chicks have to return to the mother for brooding when their body temperature approaches 35°C (Theberge and West, 1973); they apparently use their thermogenic capacity only to restrict their cooling rate so that the duration of their feeding excursions becomes less dependent on ambient temperature (Jørgensen and Blix, 1988).…”

Development of temperature regulation in the grey partridge Perdix perdix

“…They usually comprise a greater proportion of body mass than pectoral muscles in precocial birds at hatching (e.g. Aulie 1976c, Ricklefs 1979. Later, the mass of the pectoral muscles cert ainly exceeds that of the leg muscles together with their increased capacity for heat produ ction.…”

Homeothermy in neonatal chicks exposed to low environmental temperature with or without intracerebroventricular administration of corticotropin‐releasing factor

“…The ability of chicks to regulate body temperature during the post‐hatching period increases in an age‐dependent manner and birds become completely homeothermic by the age of 10 days [19]. During development, birds increase their capacity to regulate body temperature, as the size and maturity of the skeletal muscles and other organs that generate heat in response to decreasing body temperature increase [20,21]. The development of thermoregulation is also promoted by a decrease in the thermal conductance of the chick resulting from increased size and insulation of the body [22].…”

Adaptations to polar life in mammals and birds

“…The ptarmigan chick and reindeer and muskoxen calves are typical examples. The ptarmigan chicks hatch with an effective down plumage and are able to travel large distances even on their first day, and they have a substantial thermogenic capacity, which is based primarily on shivering in their breast muscle (Aulie and Steen, 1976). Even so, the chicks have to return to the mother for brooding when their body temperature approaches 35°C (Theberge and West, 1973); they apparently use their thermogenic capacity only to restrict their cooling rate so that the duration of their feeding excursions becomes less dependent on ambient temperature (Jørgensen and Blix, 1988).…”

Development of temperature regulation in the grey partridge Perdix perdix

“…They usually comprise a greater proportion of body mass than pectoral muscles in precocial birds at hatching (e.g. Aulie 1976c, Ricklefs 1979. Later, the mass of the pectoral muscles cert ainly exceeds that of the leg muscles together with their increased capacity for heat produ ction.…”

Homeothermy in neonatal chicks exposed to low environmental temperature with or without intracerebroventricular administration of corticotropin‐releasing factor

“…The ability of chicks to regulate body temperature during the post‐hatching period increases in an age‐dependent manner and birds become completely homeothermic by the age of 10 days [19]. During development, birds increase their capacity to regulate body temperature, as the size and maturity of the skeletal muscles and other organs that generate heat in response to decreasing body temperature increase [20,21]. The development of thermoregulation is also promoted by a decrease in the thermal conductance of the chick resulting from increased size and insulation of the body [22].…”