Abstract

GRIGERA, Dora  and  PAVIC, Carolina. Bird assemblages at a burnt and an undisturbed site in a forest area in northwest Patagonia, Argentina. Hornero [online]. 2007, vol.22, n.1, pp.29-37. ISSN 0073-3407.

Bird censuses were carried out in an undisturbed site and in a site affected by fire in an area of the Arroyo Challhuaco basin, Nahuel Huapi National Park, Argentina. The density and feeding substrates of each bird species were recorded. Twenty four bird species were recorded, 19 in the undisturbed site and 15 in the burnt site. Some bird species present in the undisturbed site were absent or present at lower densities in the burnt site. These species feed on the foliage, branches and trunks, or inhabit moist sites and sites with high plant cover. They would be at a disadvantage in the burnt site because of the reduction in feeding substrates and the alteration of their habitat due to the effects of fire on the vegetation. Most of the species found in the burnt site but absent or present at lower densities in the undisturbed site are ground feeders. Their positive response to the disturbance could be due to a greater availability of food resources in the ground, and to structural changes in the vegetation that are favourable for food gathering. Species diversity was higher in the burnt site. This may be explained by the fact that fire increased spatial heterogeneity and generated changes in resource availability. Some species inhabiting the burnt site could use other habitats to cover all of their habitat requirements.

Keywords : birds; fire; Patagonia; trophic ecology.

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