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Universidad de Buenos Aires (2006)

Selection of foraging sites by granivorous birds in the Monte desert

Milesi, Fernando Adrián

Titre : Selection of foraging sites by granivorous birds in the Monte desert

Selección de sitios de alimentación por aves granívoras en el desierto del Monte

Auteur : Milesi, Fernando Adrián

Université de soutenance : Universidad de Buenos Aires

Grade : Doctor en Ciencias Biológicas 2006

Résumé
The use of foraging sites by granivorous birds was studied in the algarrobal (mesquite open forest) of the Reserve of Ñacuñán (Mendoza, Argentina) in relation to vegetation struc- ture and the heterogeneity in seed abundance. Non-random patterns of use at different spatial and temporal scales were found by means of direct observations and seasonal ex- periments of seed removal. At big scales, birds preferred sites with more cover and not farther than 5–10 m from tall trees. At small scales, the patterns at the guild level aggre- gated the differences between species and the influence of phenology. Pre-dispersal seed predation was selective according to the main foraging technique of the birds (use of low branches). Post-dispersal seed predation was not restricted to microsites with particular characteristics. Birds explored preferentially those microsites with characteristics correlated to low seed abundance in the soil, even when a series of experiments in aviaries showed that the estimation of seed abundance in a microsite is more important than the use of environmental indicators or other potentially significant factors. The heterogeneity of the seed bank seems to be a consequence of the use of space by birds (a “top-down” effect) rather than a cause of it (a “bottom-up” effect).

Mots clés : AVES GRANIVORAS ; BANCO DE SEMILLAS ; RELACIONES TROFICAS ; ESTRUCTURA DE LA VEGETACION ; SELECCION DE HABITAT ; COMPORTAMIENTO DE ALIMENTACION ; USO DEL ESPACIO ; ESCALAS ESPACIALES Y TEMPORALES ; DESIERTO DEL MONTE ; RESERVA DE ÑACUÑAN ; GRANIVOROUS BIRDS ; SOIL SEED BANK ; TROPHIC INTERACTIONS ; VEGETATION STRUCTURE ; HABITAT SELECTION ; FORAGING BEHAVIOUR ; USE OF SPACE ; SPATIAL AND TEMPORAL SCALES ; MONTE DESERT ; RESERVE OF ÑACUÑAN

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Page publiée le 29 septembre 2017, mise à jour le 12 février 2020