Impact of hand-rearing on morphology and physiology of the capercaillie (Tetrao urogallus)

Morphological and physiological disparities between 20 captive and 11 wild capercaillies were determined. Birds, their pectoral and leg muscles, heart s, livers and gizzards were weighed. The length of small intestines and cae ca were measured. Haemoglobin, haematocrit, glucose, triglycerides, total p rotein. uric acid and thyroid hormones as well as the cytochrome c-oxidase activity of the pectoral muscle and heart were determined. The glycogen and protein contents of pectoral and leg muscles and liver were analysed. Chem ical composition (water, fat, protein, ash) of muscles and liver was determ ined. Captive males had heavier pectoral muscles than wild ones. The result was opposite in females. Wild birds had heavier hearts, livers, and gizzar ds, and also longer small intestines and caeca than captive birds. The cyto chrome c-oxidase activity of pectoral muscle and heart was higher in wild t han in hand-reared birds. The chemical composition of livers of wild birds differed significantly from that of hand-reared capercaillies. Plasma uric acid and T-4 concentrations were higher in captive than in wild birds. The observed differences in digestive system and liver can result in diminished ability of captive birds to utilise natural food nutrients. Decreased cyto chrome c-oxidase activity of hand-reared birds call affect their takeoff an d flying capacity and increase their vulnerability to predation. These fact s may contribute to the low survival of hand-reared birds after release. (C ) 2000 Elsevier Science Inc. All rights reserved.