PARENT SESSION
Contributed Oral Session 18: Avian Communities and Populations
Monday, August 8, 8:00 AM - 11:30 AM, Meeting Room 524 C, Level 5, Palais des congrès de Montréal
Landscape structure constrains the dispersal of a mobile songbird: A paradox?
Matthysen, Erik*,1, Adriaensen, Frank1, Grosbois, Vladimir1, 2, 1 University of Antwerp, Antwerpen, Belgium2 CNRS - CEFE, Montpellier, France
ABSTRACT- Small songbirds have intrinsically high locomotory capacities compared to other organisms of the same body size, and therefore movement patterns could be expected to be relatively insensitive to fine-grained landscape structure. Nevertheless, many songbird species have restricted dispersal and respond negatively to isolation of habitat patches. To better understand the relationship between landscape structure, movement behavior and realized disperal, we studied daily movements as well as natal dispersal of a forest-restricted passerine, the Great Tit Parus major, in a study area of 10 km2 containing 15 forest patches of 1 to 15 ha. Birds are physically able to fly across the entire area in less than an hour, and winter observations showed that individual birds commute daily between roosting and feeding sites over distances of 500 m or more. Despite this high mobility, we found several indications that dispersal is not neutral with respect to fine-grained landscape structure. First of all, up to 30% of birds never left their natal forest patch, and this proportion was significantly higher compared to similar study plots embedded in larger forest. Secondly, dispersal between forest patches was positively related to an index of between-patch connectivity (based on least-cost paths). Thirdly, dispersal directions were spatially autocorrelated, i.e. birds born in nearby nestboxes moved in similar directions, presumably in response to the surrounding landscape structure. We hypothesize that the influence of landscape structure on dispersal reflects settlement decisions taken early in life when birds are less mobile. In particular, we will discuss the potential impact of early experiences gained during family movements.
Key words: fragmentation, connectivity, dispersal, behavior