Breeding microhabitats of three sympatric acrocephalinae species (Aves) in northwestern italy

Abstract

This study examines the characteristics of the breeding microhabitats of three Acrocephalinae (Aves) species inhabiting a marshland surrounding Lake Alserio (NW Italy). A total of 45 territories (24 for Acrocephalus scirpaceus, 13 for Acrocephalus arundinaceus and 8 for Acrocephalus palustris) were mapped. In each territory 18 environmental and vegetation variables were measured in 3 to 5 sampling plots in the estimated centre of the territory or in the singing perches of males. Data were subjected to Principal Component Analysis (PCA) and to Discriminant Function Analysis (DFA). According to PCA, the breeding microhabitats of the species are ordered along the first principal component, which is strongly related to several structural and cover variables. Horizontal overlap of territories was observed for A. scirpaceus and A. arundinaceus, but not between these and A. palustris. Conversely, DFA showed that breeding microhabitat configurations are different for A. arundinaceus as compared with A. scirpaceus and A. palustris, but not completely distinguishable between the last two species. In conclusion, the data suggest that A. arundinaceus and A. scirpaceus have different ecological requirements and their territories may overlap where the vegetation is suitable for both species. On the other hand, A. scirpaceus and A. palustris have partially similar ecological requirements, but are horizontally well‐spaced, in agreement with the hypothesis of their interspecific territoriality. © 1989 Taylor & Francis Group, LLC.