Habitat selection by the Dusky-legged Guan in the “Delta del ParanᔠBiosphere Reserve, Argentina

MALZOF, SILVINA LAURA; QUINTANA, RUBEN DARIO; BRANZZINI, AGUSTINA; CARIDAD, PABLO

Hamburgo, Alemania

Congreso; XXIV International Ornithological Congress; 2006

The Dusky-legged Guan (Penelope obscura) is the southernmost species of the Cracidae family, inhabits riparian forests of northeastern Argentina. The subspecies P. o. obscura reaches the southern limit of its distribution in the Paraná River Delta in Argentina. Nowadays, due to a long history of man intervention, the forests of this region are represented by a complex mosaic of willow and poplar plantations, secondary forests and some relict patches of the native forest. The objective of the study was to analise habitat selection at macrohabitat scale, considering the guans abundance in the different types of water courses present in the “Delta del ParanᔠBiosphere Reserve during fall and spring of 2005. A number of different kinds of streams and rivers were examined in order to estimate the relative abundance of guans. We sailed along 309 km of rivers and streams in fall and 302 km in spring, where 120 and 62 guans were sighted, respectively. The water courses were classified according to their width and depth into 5 categories. The average number of guans per covered kilometer was 0.39 guans/km in fall and 0.21 guans/km in spring. Analysis of habitat selection was evaluated with the method suggested by Manly et al. (1995). The expected and observed proportions of dusky-legged guans for each water course category were recorded. Our results show that in the Fall, guans selected category 3 streams (41-60 m wide and 1-3 m deep) in proportions greater than availability, while in spring the birds selected category 2 streams (21-40 m wide and <1m deep) in proportions greater than availability. The other water courses were used according to availability, except for the large rivers (category 5) which were never used. This shows clearly the need for conservation of the smaller streams to maintain the Reserve guan population –something especially important in view of the current forestry activities which, throughout the year, has affected some of the forests on their banks.