Seasonal and daily fluctuations of aquatic birds in Saco da Fazenda, Itajaí-sc

DOI: 10.15343/0104-7809.20113514754

Abstract

Saco da Fazenda ecosystem, in spite of the impact caused by the flow of effluent domestic and industrial sewage coming
from Itajaí-Açu River, shelters a great diversity of birds. The knowledge of the composition of avifauna becomes crucial in the characterization
of this environment, since in threatened ecosystems, as estuaries, we may verify alterations in biodiversity and abundance
due to the influence of adjacent areas on the ecosystem. From July 2006 and April 2007 we did biweekly censuses in the assembly of
aquatic birds, with two hour intervals from 8:00 P.M. and 2:00 AM. We registered 29 aquatic birds species, distributed in 25 genres
and 13 families, being 11 of constant occurrence (37.9%), six accessory (20.6%) and 12 species of casual presence (41.3%). We found
expressive differences in the abundance of aquatic birds among biweekly and daily intervals. Daily average fluctuation presented a small
increment from the first interval of counting, and reached the highest values from 14:00 to 16:00 PM (256.2 ± 24.9), with a consecutive
lesser value around 18:00 PM (56,3 ± 14,6), last schedule of census.