Comparative development in captive and migratory populations of the barnacle goose

The development of the locomotory muscles and associated skeletal structures of goslings and adults from a captive population of barnacle geese (Branta leucopsis) was compared with that from a wild migratory population. There was no significant difference between flight-muscle development of wild and captive goslings up to 7 wk of age, when the birds are first able to fly. In contrast, mass-specific citrate-synthase activity in the semimembranosus leg muscle of the captive goslings was significantly lower than that of wild goslings by 5 wk of age. During the postfledging premigratory period, captive geese showed significantly higher values for both mass and mass-specific citrate-synthase activity of the leg muscles than those of wild birds. Premigratory wild geese had significantly higher citrate-synthase activity in the pectoralis muscles and larger cardiac ventricular mass (by ca. 20%-25%) than both wild postmoulting and captive premigratory adults. Total flight-muscle mass was only slightly reduced (by ca. 10%) in long-term captive adults compared with wild premigratory adults. Most of the differences between these two populations appear primarily to reflect their relative levels of activity and/or differences in their ambient environment, rather than any intrinsic differences in developmental or adult physiology.