Mäkinen, T., Pyörnilä, A., Putaala, A. & Hissa, R. 1997: Effects of captive rearing on capercaillie Tetrao urogallus physiology and anatomy. - Wildl. Biol. 3: 294.
Captive breeding of game birds for reintroduction or population enhancement has been exercised as a form of conservation biology and wildlife management. Relatively little attention has been given to the quality of the captive-reared birds which might be an important factor in post-release survival. In this study the physiological and anatomical characteristics of 12 (4 females, 8 males) captive-reared capercaillie Tetrao urogallus were compared with those of eight wild birds (4 females, 4 males). In September 1995, samples were collected consisting of blood biochemical parameters (haemoglobin, glucose, total proteins, free fatty acids, uric acid, triglycerides, cholesterol and thyroid hormones) and tissue analyses (tissue composition, glycogen content, cytochrome c-oxidase activity, muscle fibre type). In addition, anatomical measurements (body, internal organ and muscle weights, intestinal lengths) were made. Wild and captive capercaillie differed in size of the gastrointestinal tract and in properties of the flight muscle. Wild capercaillie had a longer small intestine (range 20-39 cm, P < 0.001) and caecum (range 16-21 cm, P = 0.001), and a heavier gizzard (P = 0.017) than captive birds probably because of lower digestibility and nutritional value of the natural diet compared to commercial poultry food. Wild capercaillie had a heavier heart (P = 0.003), liver (P = 0.005) and leg muscles (P = 0.005) than captive birds. The pectoral muscle of wild birds had a higher (P = 0.002) activity of cytochrome c-oxidase (a respiratory chain enzyme), probably associated with better flying ability as compared with captive birds. Histological examination revealed two different fibre types in the pectoralis muscle. In wild birds, fast twitch oxidative glycolytic (FOG) predominated (80-88%) with the remainder being fast twitch glycolytic (FG) cells. The higher staining density for succinate dehydrogenase (SDH) and the larger amount of FOG fibres (39%) apparently provides wild capercaillie with improved potential for sustained flight compared to captive birds. Blood biochemical parameters showed significantly higher values of glucose (P = 0.020), cholesterol (P < 0.001) and uric acid (P = 0.0015) in captive birds which probably reflects the high nutritional value of commercial poultry diet. Thus, there were marked anatomical and physiological differences between captive and wild capercaillie that might affect release success. Therefore, bird quality and preconditioning should be considered in release programs using captive-reared birds.
Key words: anatomy, capercaillie, captive rearing, physiology, Tetrao urogallus, translocations
Tiina Mäkinen, Ahti Pyörnilä, Ahti Putaala & Raimo Hissa, University of Oulu, Department of Biology, FIN-90571 Oulu, Finland