Abstract: The Dusky-legged Guan (Penelope obscura) is the southernmost species of the Cracidae family, inhabits riparian forestes in southern Brazil, Paraguay and Argentina. The subspecies P. o. obscura reaches the southern limit of its distribution in the Paraná River Delta in Argentina. Although P. obscura is considered vulnerable, in our country is still under considerable hunting pressure and it is locally endangered in some areas. The Paraná River Delta, on the other hand, constitutes an endemic ecoregion of Argentina, which has been deeply modified since the middle of the 19th century. Nowadays, due to a long history of human intervention, the riparian forest is represented by a complex mosaic of willow and poplar plantations, secondary forests and some relict patches of the native forest. At present it still maintains a high biodiversity but some urban and productive projects threaten its preservation. Our objective will to provide understanding of the nature of the relationship between Dusky-legged Guan and its habitat in the "Delta del Paraná" MAB Reserve through the integration of field work, field interviews to local inhabitants and its integration in a Geographic Information System. Field research is essential to the future of cracids but field data on which to base effective management plans for these species is sparse. In this sense, the ecology of the Dusky-legged guan remains poorly known. We consider the current project as an important starting point for increasing the knowledge about this cracid species and its habitat in this ecoregion, including the effectiveness of the MAB Reserve in protecting this species.

Dr. Quintana received additional funding for the project in 2005 through the Zoo's Small Grants program (view project report).

Project Report

A number of different kinds of streams and rivers were examined in order to estimate the relative abundance of guans. The team sailed the water courses of the "Delta del Paraná" Biosphere Reserve (DPBR) on a motorboat at 50 km/h from 8:00 to 11:00 am and 3:00 to 6:00 pm. All in all, the team sailed along 309 km of rivers and streams, including some 41.909,2 hectares lying in the core, buffer, and transition areas where 120 guans were sighted. 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. The coordinates of each of the sighting spots was identified by GPS in order to locate them in a digital map of the reserve.

Other parameters were also established to characterize each course of water:

1. Width of levee
2. Number of large rivercraft
3. Number of medium sized rivercraft
4. Number of small rivercraft
5. Number of inhabited houses
6. Number of deserted houses

Sightings of guans around water courses of types 2 and 3 were more frequent, therefore they were grouped in order to compare streams with and without sightings. Variables a, b, c, d, e, and f will be used in the comparison, as they influence the presence of guans.

The following variables were also recorded

1. Weather conditions (wind, cloud cover, and temperature)
2. Animal behavior at the time of sighting
3. Sighting distance from the animal

165 sites belonging to 92 stations placed along several rivers and streams within the RBDP were sampled, and site coordinates were established by means of GPS. The sites were located on each opposed bank and stations lay 1000 m from each other. Each site was classified as "used" and "unused" depending on the presence of guans or signs of occupation such as feathers, spoor, nests or dustbaths or traces thereof.

At each site a 10x10 m square was drawn in which a number of variables related to vegetation structure and composition were observed including grass, bush and tree layer covering, height of the high and low arboreal stratum, chest-high diameter and density of tree species, abundance, covering and phenologic state of each individual plant species, creepers density and their disposition on the trees, number of fallen trees, and number of tree stumps. Environmental variables were also estimated, such as percent of naked ground and leafy accumulation, width of the water course and the levee, and dominant physiognomy of the site (active plantations, secondary forests, gardened areas, fruit orchards, etc…). The neighboring areas of the sampled site were also characterized to define the structure of the patches at each particular site.

Out of the 165 sampled sites, 48 had been used by guans while the other 117 showed no sign of activity or presence whatsoever.

As part of the effort to make this project known to the community at large, a webpage (http://www.ege.fcen.uba.ar/penelope/) was created including information about the Delta region and this project, as well as images of the field campaigns. In addition, a poster was presented during "Biology Week" at the Facultad Ciencias Exactas y Naturales, University of Buenos Aires, an event aimed at promoting science in high schools with a biology curriculum. In early September, a poster on the guan feeding habits will be presented at the Argentine Meeting on Ornithology to be held in Buenos Aires. A short article for publication in the en el Bulletin of the IUCN/Birdlife/WPA Cracid Specialist Group is also being written.