Áreas libres de hielo y su relación con ensambles de aves nidificantes antárticas, isla Livingston, Antártica
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1992
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Un estudio detallado de los microhábitats de nidificación de ocho aves antárticas en península Byers, isla Livingston, reveló la heterogeneidad del hábitat y la plasticidad del área libre de hielo que año a año sufre variaciones en su extensión. Este fenómeno determina que sea posible distinguir al menos ocho microhábitats susceptibles de ser utilizados por dichas aves, verificable por, a lo menos, tres características: un uso masivo de la franja libre de hielo (deducible tanto por el número como por la biomasa de las aves presentes allí); un uso intensivo (todas las aves nidificantes se
reprodujeron en este sector y durante un corto período) y un uso compartido (puesto que varios microhábitats fueron usados por más de una especie). Como consecuencia de estas características, es posible inferir y interacciones entre poblaciones de usaron sustratos comunes y que se expresaron en: diferencias de tiempo de anidación (Larus dominicanus) nidificó un mes antes que Catharacta lonnbergi; alotopía en uso de sustratos similares, pero no idénticos (Macronectes giganteus utilizó roca desnuda para nidificar, mientras Sterna vittata lo hizo en rocas de iguales características, pero
cubiertas de musgos y líquenes) y protección contra depredadores, al usar grietas en rocas meteorizadas para anidar (Oceanites oceanicus y Fregetta tropica, aunque no es descartable una explicación de carácter térmico para este tipo de selección). Las características y consecuencias descritas, sugieren que el hábitat podría constituir un factor relevante en la estructuración de ensambles de aves en islas antárticas.
A detailed study of nesting microhabitat of Aantarctic birds at Byers Peninsula, revealed that the habitat es very complex. This is due to habitat plasticity (ice-free strips) as result of differential thaw from year to year. This phenomenon allows us to distinguish at least eight kinds of microhabitats used by birds, with three distinct features: a massive use of the ice-free strip (deduced both by the number as well as the biomass of birds that used this strip); an intensive used (all the nesting birds used only this strip for breeding); and a shared used (more than one microhabitat is used by more than one species). As a consequence of these features it is possible to infer interactions among the populations that used common substrates which are expressed by: differences in nesting time (Larus dominicanus breeds about one month before Catharacta lonnbergi); allotopy with respect to similar but not identical substrates (Macronectes giganteus uses naked rock outcrops and Stema vittata uses outcrops covered with lichens and mosses); and avoidance of predation by choosing sheltered sites in beds of fractured rocks (Oceanites oceanicus and Fregetta tropica. Nevertheless, there is an alternative explanation which might be related to the thermal requirements of small birds).
A detailed study of nesting microhabitat of Aantarctic birds at Byers Peninsula, revealed that the habitat es very complex. This is due to habitat plasticity (ice-free strips) as result of differential thaw from year to year. This phenomenon allows us to distinguish at least eight kinds of microhabitats used by birds, with three distinct features: a massive use of the ice-free strip (deduced both by the number as well as the biomass of birds that used this strip); an intensive used (all the nesting birds used only this strip for breeding); and a shared used (more than one microhabitat is used by more than one species). As a consequence of these features it is possible to infer interactions among the populations that used common substrates which are expressed by: differences in nesting time (Larus dominicanus breeds about one month before Catharacta lonnbergi); allotopy with respect to similar but not identical substrates (Macronectes giganteus uses naked rock outcrops and Stema vittata uses outcrops covered with lichens and mosses); and avoidance of predation by choosing sheltered sites in beds of fractured rocks (Oceanites oceanicus and Fregetta tropica. Nevertheless, there is an alternative explanation which might be related to the thermal requirements of small birds).
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Serie Científica, nº 42, pp. 69-75, 1992