Spatial behaviour in the Aquatic Warbler (Acrocephalus paludicola) during mating and breeding

The range use of both sexes of the Aquatic Warbler was studied during two b reeding seasons by radio-tracking. Males used home ranges of up to 8 ha. Th ese home ranges overlapped by up to 74 %, (mean 51 %) between individuals. During the mating period and prior to nesting, females used isolated sites of 2.8 to 6.4 ha (mean: 4.2 ha) within activity ranges of 100 to 160 ha (me an: 120 ha). Home ranges of different females overlapped by up to 20 %. How ever, during nest-building and incubation, the average size of home ranges in females was only 1.6 ha. Since no constant ranges were observed, we conc lude that Aquatic Warblers are not territorial in the breeding season.