Winter Starvation in Captive Common Barn-Owls: Bioenergetics during Refeeding

ABsTRACr.-The bioenergetics of eight captive Common Barn-Owls (Tyto alba alba) acclimated at 5?C were studied during the restoration of a 30% reduction in body mass following a period of total food deprivation. The eight-day period during which body mass was restored (Refeeding I) was compared with a five-day prefasting period (Feeding), corresponding to steady body mass and a six-day period (Refeeding II) of stabilization at a new steady state. Food was given ad libitum throughout the feeding periods. During Refeeding I, the rate of increase in body mass (13.9 ? SD of 1.0 g/24 h in females and 9.2 ? 0.8 g/24 h in males) was close to the maximum value for growth of captive or wild owlets. It was achieved by a 1.63-fold increase in gross energy intake and daily metabolized energy, respectively, of 370 ? 42 and 275 ? 31 kJ/d during Feeding. In contrast to the clear increase in food assimilation efficiency observed in other species during refeeding, the high rate of energy intake and body mass restoration in the Common Barn-Owl was associated with only a slight increase in assimilation efficiencies: 52.0 ? 2.2% versus 49.1 ? 1.0% during Feeding for dry mass; and 75.5 ? 1.1% versus 74.1 ? 0.6% for energy. This slight increase could only be attributed to a reduction of the energy lost in pellet production (i.e. to a higher effectiveness in gastric digestion). The energetic cost of daily change in body mass was estimated in both sexes and both feeding periods, and appeared to be constant (10.8 ? 1.1 kJ/g fresh body mass). Using this value, the part of the daily metabolized energy invested in the existence metabolism was calculated. After four days of refeeding, existence metabolism paradoxically appeared similar or even higher than before fasting, while the body mass was still lower than the initial value. Thus, in contrast to the laboratory rat (Rattus norvegicus) or humans, the Common Barn-Owl is unable to enhance restoration of body reserves by minimizing existence requirements when refed ad libitum after a period of starvation. This might be partly due to the maintenance of a high locomotor activity throughout starvation and refeeding. Received 3 October 1991, accepted 5 May 1992.

[1]  Y. Handrich,et al.  Winter Starvation in Captive Common Barn-Owls: Physiological States and Reversible Limits , 1993 .

[2]  C. D. Marti.  Sex and Age Dimorphism in the Barn Owl and a Test of Mate Choice , 1990 .

[3]  S. Daan,et al.  Intraspecific Allometry of Basal Metabolic Rate: Relations with Body Size, Temperature, Composition, and Circadian Phase in the Kestrel, Falco tinnunculus , 1989, Journal of biological rhythms.

[4]  J. Myers,et al.  Assimilation efficiency in birds: a function of taxon or food type? , 1989 .

[5]  S. Daan,et al.  Time Allocation in the Kestrel (Falco tinnunculus), and the Principle of Energy Minimization , 1988 .

[6]  E. Duffey.  The barn owl in the British Isles. Its past, present and future , 1988 .

[7]  S. Daan,et al.  ECOLOGICAL ENERGETICS OF THE KESTREL - DAILY ENERGY-EXPENDITURE THROUGHOUT THE YEAR BASED ON TIME-ENERGY BUDGET, FOOD-INTAKE AND DOUBLY LABELED WATER METHODS , 1988 .

[8]  Eliot Stellar,et al.  The effects of repeated cycles of weight loss and regain in rats , 1986, Physiology & Behavior.

[9]  J. H. Carothers,et al.  Ecological, Morphological, and Bioenergetic Correlates of Hunting Mode in Hawks and Owls , 1985 .

[10]  P. W. Wagner,et al.  Winter mortality in common barn-owls and its effect on population density and reproduction , 1985 .

[11]  K. Hamilton.  Food and energy requirements of captive barn owls Tyto alba. , 1985, Comparative biochemistry and physiology. A, Comparative physiology.

[12]  J. Hill,et al.  Effects of fasting and restricted refeeding on utilization of ingested energy in rats. , 1984, The American journal of physiology.

[13]  S. B. Chaplin,et al.  Body temperature regulation in red-tailed hawks and great horned owls: responses to air temperature and food deprivation , 1984 .

[14]  H. Wijnandts,et al.  Ecological Energetics of the Long-Eared Owl (Asio Otus) , 1984 .

[15]  J F Harper,et al.  Peritz' F test: basic program of a robust multiple comparison test for statistical analysis of all differences among group means. , 1984, Computers in biology and medicine.

[16]  J. Kirkwood.  A limit to metabolisable energy intake in mammals and birds , 1983 .

[17]  P. Björntorp,et al.  Refeeding after fasting in the rat: effects on body composition and food efficiency. , 1982, The American journal of clinical nutrition.

[18]  M. V. Stalmaster,et al.  Food Consumption and Energy Requirements of Captive Bald Eagles , 1982 .

[19]  H. Southern,et al.  The Barn Owl , 1982 .

[20]  J. Kirkwood.  The partition of food energy for existence in the kestrel (Falco tinnunculus) and the barn owl (Tyto alba) , 1979 .

[21]  O. Evanson,et al.  Meal to pellet intervals in 14 species of captive raptors. , 1976, Comparative biochemistry and physiology. A, Comparative physiology.

[22]  O. Evanson,et al.  Gastric digestion in some raptors. , 1975, Comparative biochemistry and physiology. A, Comparative physiology.

[23]  J. Raczyński,et al.  The effect of digestion on the osteological composition of owl pellets , 1974 .

[24]  O. Evanson,et al.  Food consumption and energy, water, and nitrogen budgets in captive great-horned owls (Bubo virginianus). , 1973, Comparative biochemistry and physiology. A, Comparative physiology.

[25]  J. Gessaman.  Bioenergetics of the Snowy Owl (Nyctea Scandiaca) , 1972 .

[26]  Bo Frylestam.  Uber Wanderungen und Sterblichkeit beringter skandinavischer Schleiereulen Tyto alba , 1972 .

[27]  J. R. Owen.  THE BIOENERGETICS OF CAPTIVE BLUE-WINGED TEAL UNDER CONTROLLED AND OUTDOOR CONDITIONS , 1970 .

[28]  R. Graber.  Food and oxigen consumption in three species of owls (STRIGIDAE) , 1962 .

[29]  S. C. Kendeigh.  Effect of Temperature and Season on Energy Resources of the English Sparrow , 1949 .

[30]  H. Thomson.  FOOD AND ENERGY , 1910 .