The Size and Composition of Sheld-Geese Populations and their Food Consumption on Different Vegetation Types in the Falkland Islands

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Abstract
Densities of upland and ruddy-headed geese [Chloephaga picta leucoptera and C. rubidiceps] were determined for a variety of ''natural'' pastures in the Falkland Islands. Both species had a similar pattern of abundance along valleys; highest densities occurring during breeding in spring and summer. The 2 spp. had a similar pattern on pond-greens but peak densities occurred in summer when flocks gathered for moulting flight feathers. On Poa-greens upland geese were more abundant than ruddy-headed geese. The whitegrass and diddle-dee associations were used only by upland geese; whitegrass mostly in winter and diddle-dee in late summer and autumn. Seasonal changes in densities were also described for improved pastures. Established (> 2 yr old) Holcus lanatus reseeds had highest densities of upland geese in winter; coastal reseeds had another peak in summer when moulting flocks gathered. Establishing (< 2 yr old) reseeds composed of several grass species had the highest densities of geese but the annual density declined as the reseeds aged. The median group size for upland and ruddy-headed geese was almost always 2. The percentage of 1st-yr upland geese varied seasonally, and between vegetation types. The composition of the upland goose population in terms of ''pairs'', ''family parties'' and ''other groups'' is described. All components of the population conflicted with farming interests. Herbage consumption by geese on different vegetation types was estimated from population density and daily food intake. Consumption was greatest on greens and reseeds, and amounted to 17% of the herbage production on Poa-greens and a maximum of 6% on a H. lanatus reseed. The geese populations took only .apprx. 2% of the total annual herbage production of North Arm farm, while sheep and cattle ate .apprx. 20%. The geese populations do not present a serious economic threat to the sheep industry.