Settlement Period and Function of Long-Term Territory in Tropical Mangrove Passerines

We studied the territorial behavior of four insectivorous passerines residing in a tropical mangrove of northeastern Venezuela. Data were obtained through mist-netting and direct observation of color-banded individuals, regularly scheduled over two complete annual cycles. Seasonal variation in food resources (arthropods) and the birds' diet also were evaluated. A chronological cluster analysis was used to determine the settlement periods of territories, the former being illustrated by the probabilistic Jennrich-Turner method. Three of the four species hold year-round territories. These long-term territories were settled only once a year, immediately after the breeding season when food was abundant. The territorial settlement was synchronous among all individuals of a species, favoring strong modifications of the territorial mosaic. Considering the absence of territorial settlement prior to breeding and the high stability of territorial mosaics even during periods of low food abundance, territoriality during the non-breeding season primarily appears to ensure a breeding site for the next reproductive period. These results contrast with those from temperate regions where territoriality over the non-breeding season primarily enhances the survival of individuals during periods of food shortage.