Birds of Indian Subcontinent

Thermal Balance in the European Coot Fulica atra Exposed to Temperatures from -28°C to 40°C

Publication Type:Journal Article
Year of Publication:1985
Authors:Brent, R, Pedersen, PF, Bech, C, Johansen, K
Journal:Ornis Scandinavica
Date Published:1985
ISBN Number:00305693
Keywords:Fulica, Fulica atra, Rallidae
Abstract:Body temperature, ${\rm O}_{2}\text{-uptake}$ , evaporative water loss, ventilation and heat dissipation from the feet were measured at various ambient temperatures in the European Coot Fulica atra. Resting metabolic rate within the thermoneutral zone (20-34°C) was $6.08\ {\rm W}\cdot {\rm kg}^{-1}$ . Below the lower critical temperature, the standard metabolic rate (SMR) increased according to the formula: ${\rm SMR}=12.55-0.33\cdot {\rm T}_{{\rm A}}$ , where SMR is expressed in ${\rm W}\cdot {\rm kg}^{-1}$ , and T A is ambient temperature in °C. Body temperature averaged 39.6°C ± 0.6°C at ambient air temperatures between -28°C and 30°C. Evaporative heat loss was insufficient to regulate body temperature during heat stress ( ${\rm T}_{{\rm A}}=40{{}^\circ}{\rm C}$ ), and prolonged exposure to this temperature when the birds were out of water resulted in hyperthermia. At 20°C respiratory frequency and tidal volume were 20 breaths per minute and 9.7 ml per kg, respectively. Moderate heat loads ( ${\rm T}_{{\rm A}}=35{{}^\circ}{\rm C}$ ) doubled respiratory frequency, while tidal volume fell slightly. With the feet water immersed, the coots were able to increase heat loss from the feet by a factor of 185 when the ambient temperature was raised from 10°C to 40°C, indicating a major role of the feet for maintenance of thermal balance.
Short Title:Ornis Scandinavica
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith