Varia??o sazonal na abundancia de Larus dominicanus (Aves, Laridae) no Saco da Fazenda, Itajaí, Santa Catarina

摘要

The gull Larus dominicanus (Lichtenstein, 1823) is one of the most common coastal seabirds of the Brazilian coast, exploring several habitats and food types. The estuary known as Saco da Fazenda is an important feeding and resting area for the species. In this paper, we evaluate the population structure of L. dominicanus in this area. From February/2004 to January/2005, gulls were monitored in monthly census in Saco da Fazenda at intervals of two hours from 6:00 a.m. to 8:00 p.m. The fluctuations observed in the abundance of L. dominicanus along the year were significant, with the highest counts in March (181.6 ± 35.1) and the lowest in October (21.0 ± 4.9). Birds began occupation of the estuary in the first hours of the day, peaking at 2:00 p.m. (72.4 ± 14.2). In the end of the day the abundance reduced significantly with the lowest abundances at 8:00 p.m. (3.8 ± 3.0). Principal Components Analyses (PCA) revealed a positive correlation between the abundance of gulls and the temperature of the air. The fluctuations found in the abundance of L. dominicanus during this study can be correlated with different phases of the breeding cycle, while differences observed in the number of gulls along the day may be related to the activity of fishing fleet.