Effects of neighbours: costs of polyterritoriality in the Fan-tailed WarblerCisticola juncidis

Abstract

The Fan-tailed Warbler Cisticola juncidis is a polygynous and territorial passerine. Eleven territories were established at an edge habitat over the 3 years of study. All of the owners which were adjacent to only one neighbouring territory attempted to hold secondary territories and four males succeeded in establishing secondary territories. On the contrary, five males adjacent to two neighbours did not attempt to leave their primary territories. The probability of establishing a secondary territory in the Fan-tailed Warbler seems to depend on the risk of intrusion by neighbours.