Diet, Feeding Behaviour and Food Intake of the Upland Goose (Chloephaga picta) and Ruddy-Headed Goose (C. rubidiceps) in the Falkland Islands

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Abstract
The diet of upland and ruddy-headed geese was composed mainly of Poa annua and P. pratensis. Leaf lengths of P. annua/P. pratensis eaten on greens did not vary seasonally for upland geese and there was no significant difference in lengths taken by ruddy-headed and upland geese in winter. Berries, grass-seeds and green algae were eaten at certain seasons. Geese arrived on pastures shortly before sunrise and left shortly after sunset. Numbers varied little through the day. The 2 goose species had similar time-activity budgets though the proportion of time allotted to some activities varied seasonally, e.g., in winter a greater proportion of the day was spent grazing compared with summer. The digestive efficiency of a captive upland goose fed on grass pellets was measured directly (by measuring input and output) and indirectly (using the cell wall material of the grass as an indigestible marker). The 2 methods gave similar results (25.8% and 25.3%, respectively) indicating the accuracy of the latter method, which was then used for free-living geese. The organic matter digestive efficiencies of free-living geese varied from 27 to 34% on Poa greens for winter and summer. Fecal output was determined from frequency of defecation and weights of feces. This was converted to gross and net intakes using estimates of digestive efficiency. Gross intakes per day for male and female upland geese were 5100 and 4000 kJ, respectively, and 2600 kJ for ruddy-headed geese feeding on greens in winter. The corresponding net intakes were 1900, 1500 and 900 kJ/day. The latter values were close to estimated daily energy requirements based on published equations. The feed value of goose feces to sheep, who often eat them, was measured in terms of digestibility and N content. They had a similar digestibility and N content to good quality grass.

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