Respiratory water loss during rest and flight in European Starlings ( Sturnus vulgaris)

• Published in: Comparative biochemistry and physiology. Part A, Molecular & integrative physiology Molecular & integrative physiology, 2006-12, Vol.145 (4), p.423-432
• Main Authors: Engel, Sophia, Suthers, Roderick A., Biebach, Herbert, Visser, G. Henk
• Format: Article
• Language: English
• Subjects: Ambient temperature; Animals; Bird flight; European Starling ( Sturnus vulgaris); Exhaled air temperature; Flight, Animal - physiology; Pulmonary Ventilation; Respiration; Respiratory airflow; Respiratory frequency; Respiratory water loss; Starlings - physiology; Temperature; Water balance; Water Loss, Insensible
• ISSN: 1095-6433; 1531-4332
• DOI: 10.1016/j.cbpa.2006.07.022

Respiratory water loss in Starlings ( Sturnus vulgaris) at rest and during flight at ambient temperatures ( T amb) between 6 and 25 °C was calculated from respiratory airflow and exhaled air temperature. At rest, breathing frequency f (1.4 ± 0.3 Hz) and tidal volume V t (1.9 ± 0.4 ml) were independent of T amb, but negatively correlated with each other. Mean ventilation at rest was 156 ± 28 ml min − 1 at all T amb. Exhaled air temperature ( T exh) at rest increased with T amb ( T exh = 0.92 · T amb + 12.45). Respiratory water loss at rest averaged 0.18 ± 0.09 ml h − 1 irrespective of T amb. In flying Starlings f was 4.0 ± 0.4 Hz and independent of T amb. V t during flight averaged 3.6 ± 0.4 ml and increased with T amb ( V t = 0.06 · T amb + 2.83) as, correspondingly, did ventilation. T exh during flight increased with T amb ( T exh = 0.85 · T amb + 17.29). Respiratory water loss during flight (average REWL f = 0.74 ± 0.22 ml h − 1 ) was significantly higher than at rest and increased with T amb. Our measurements suggest that respiratory evaporation accounts for most water loss in flying Starlings and increases more than cutaneous evaporation with rising ambient temperature.