Avaliação da extensão de ocorrência e do risco de extinção de Pyrrhura griseipectus Salvadori 1900

Abstract

Northeastern Brazil has a wide diversification of biogeographic units that make up the region, one of them being the arboreal remnants of the dry and wet forest, important centers of endemism in South America. One of these endemic species is the Grey-breasted Parakeet (Pyrrhura griseipectus), which has a disjoint distribution in five brasilian northeastern locations. International Union for Conservation of Nature (IUCN) elaborate the Red List of Threatened Species. This list consists of an assessment of the conservation status of the species. In addition, description of the status of each evaluated species and includes threats to the species in question, as well as providing support for the elaboration of action plans for their conservation. The assessment of threat status have five requirements for sorting as species into threat categories. One of these is Criterion B which deals with the estimated geographic distribution by (B1) Extent of occurrence (EOO) and (B2) Area of occurrence (AOO). EOO can be calculated by following two methodologies or Minimum Convex Polygon and Concave hull, or α-hull. Within this context, the objective of this work was the application of α-hull to estimate P. griseipectus EOO's and to evaluate the degree of threat of the species following the UICN Criterion B1 estimated by α-hull. The occurrence data of P. griseipectus were obtained by monitoring four species occurrence regions. The data were tabulated and plotted in two free software, RStudio and Quantum GIS (QGIS), where the α- hull analyzes were performed to estimate the species EOO and MPC, with the new occurrence data. The maps proposed by the two methodologies for species occurrence extension shown divergences for EOO used by the UICN, changing species threat category. Taking into account the addition of new data, with the value of the area estimated by MPC the degree of threat from P. griseipectus to “Vulnerable (VU)”. Already considering the value of α-hull the degree of threat of the species is increase for "Critically Endangered (CR)". The discontinued character, already evidenced in the literature, in the distribution of Pyrrhura griseipectus leads us to endorse the α-hull method to estimate the EOO value and the result of 84 km² implies the need for a revision on the threat level of the species, taking into consideration a fifth subpopulation if it is proven valid taxonomy. In addition, we suggest that the methodology adopted by the present study be replicated for other species that have disjoint distribution restricted to the 'swamps of altitude' of northeastern Brazil.