Atropelamento de vertebrados silvestres em uma região fragmentada do nordeste do estado de São Paulo: quantificação do impacto e análise de fatores envolvidos.

Abstract

Mortality due to road kills has a great impact on natural populations. The present work had the objectives of quantifying road-killed vertebrates in a circuit of the main highways of northeastern São Paulo State, a fragmented area with several unconnected Conservation Units, and to identify factors associated with this source of mortality. For the count of road-killed animals, 52 weekly trips were performed during one year (August 19, 2002 to August 11, 2003) in a circuit of the highways SP253, SP330, SP215, SP310, SP215, SP318, SP255. The species encountered were classified in numbers of one to five, in decreasing order, according to the priority of its conservation in the area. The results from the trips were 596 animals of 81 different species: birds, 310 (52% of the total, 45 identified species); mammals, 184 (31%, 23 species); reptiles, 56 (9%, 11 species); amphibians 35 (6%, 2 species); and 11 (2%), not identified. Considering the 239,24km of the circuit 2,49 animals/km/year were killed. Considering the total effort of 12.440,48km traveled, an average of 0,048animals/km was obtained. These data were added to those supplied by other sources of information, yielding records of 746 animals: 323 birds, 266 mammals, 94 reptiles, 35 amphibians and 28 not identified. In a general way there was smaller number of road-kills in the dry period than in the rainy season, but there was great variation among some species, apparently related to their natural history. The most-frequently found species was the opossum (Didelphis albiventris), with 53 records, in other words, 28,8% of the total of mammals, 8,89% of the total of animals. The Order Carnivora had the largest number of road-killed species (4) among the mammals. There were records of threatened species at the São Paulo State such as the Maned-wolf (Chrysocyon brachyurus), Ocelot (Leopardus pardalis), Giant anteater (Myrmecophaga tridactyla) and Broad Snouted Caiman (Cayman latirostris) and of species that don't occurr naturally in the State. It was found that 70,21% of the animals of categories 1 and 2 (i.e. conservation priorities in the area) died in 47%, or 111,72km of the studied itinerary. This road segment is at a maximum distance of 10km from the nearby Conservation Units, or 5km from the river Mogí-Guaçu. Mitigatory measures were discussed, and four prioritary areas for their establishment were proposed.