* Unidade de Biologia da Conservação. Universidade de Évora, Pólo da Mitra, 7002-554 Évora. (filipescpcarvalho@yahoo.com, ondinagiga@netvisao.pt) Carvalho, F. * , Giga, O. * & Mira, A. * FACTORS DETERMINING VERTEBRATE ROAD-KILLS. A CASE STUDY IN SOUTHERN PORTUGAL. Introduction Construction of roads is one of the most important cause of habitat fragmentation and landscape modifications made by mankind. But, perhaps the most direct impact of this infrastructures among vertebrate fauna is vehicle-caused mortality. In the last years many research has been developed to seek the factors that influence vertebrate road-kill (Forman and Alexander, 1998; Trombulak and Frissell, 2000; Malo et al, 2004). Some of the factors that have been described as determinants on vertebrate road-kill are: traffic flow, temporal patterns (climatic conditions), spatial patterns (e.g. biota and road topography) (Clevenger et al, 2003) and ecological patterns (Peris & Pescador, 2004). So, the aim of this study is to evaluate vertebrate road-kill based on a long-term research, between 1995 to 2005, in Southeast Portugal. Results Discussion The higher amphibian mortality in 1996, was probably due to low rainy periods in 2005. For the mammals, Iuel et al. (2003) says that when a road has more than 4000 vehicles per day, the road becomes a strong barrier, and movement will repel many individuals, but those that try to cross the road become road causalities. So the greater mammal mortality in 2005, could be explained by this fact. Peris & Pescador (2004) also says that for passerines populations the effect of the traffic should be an important variable to explain the amount of birds road-kills. Besides traffic volume, other important variables must be taken into account, such as climatic conditions; roadside biota and topography (Clevenger et al, 2003). In this point of view, maybe the greater mortality in first part of the road section in both periods, was due to the proximity of the Portuguese Serra de São Mamede Natural Park, where important vertebrates communities occur. On the other hand, there was a greater presence of olive trees and “montado landscape” (fig.1), that supports a largest biodiversity (Pargana et al., 1996). References fig. 1 – Percentage (%) of principal biota throw the section surveyed, for each kilometre. MNT – “montado landscape”; PST – Pastureland; OLV – olive trees (Adapted from Ascenção, 2001). 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 0 2 4 6 8 10 12 14 16 18 20 22 24 26 Km % de ocupação MNT PST OLV Study area This study was made in Alto Alentejo, Portugal. The road selected is a section of the IP2 road, with 27 Km, between Portalegre and Monforte. Biota involving the road is characterised by pasturelands and extensive livestock farming areas with no trees (50,5%), “montado landscape” of Quercus ilex and Quercus suber (32,1%), and Olive trees (Olea europea) (17,4%) (fig1.). Topography along the road is 43% at the same level of the road, 38% buried and 19 % raised (Ascenção, 2001). Methods Surveys for vertebrates road-kill occurred from March 1995 to March 1997 and a second period from December 2004 and September 2005 (still going). They were made within a period of 15-days by two observers that sampled the road by car at 15 Km per hour. When a road-killed animal was found, we attempted to identify the species and then we obtained the geographic coordinate location of all road-kills using a differentially-correctable, global positioning system (GPS) unit. The data collected in 1996 and 2005 (from January to September) was compared with the traffic volume in the road during the study and with biota and topography present along the road sides.  Ascensão, F. 2001. Mortalidade de Vertebrados por Atropelamento em Estradas do Alto Alentejo. Relatório de estágio para obtenção da Licenciatura em Biologia Aplicada aos Recursos Animais – Variante Terrestres. F.C.U.L. Lisboa.  Clevenger, A.P., Chruszcz, B. & Gunson, K.E. 2003. Spatial patterns and factors influencing small vertebrate fauna road-kill aggregations. Biological Conservation, 109: 15-26.  Forman, R.T.T. & Alexander, L. E. 1998. Roads and their major ecological effects. Annu. Rev. Ecol. Syst, 29: 207-231.  IUCN, (2004). Guidelines for Using the IUCN Red list Categories and Criteria. Prepared by the Standards and Petitions Subcommittee of the IUCN SSC Red List Programme Committee.  Luell, B., Bekker, G.J., Cuperus, R., Dufek, J., Fry, G., Hicks, C., Hlavac, V., Keller, V., B., Rosell, C., Sangwine, T., Torslov, N., Wandall, B. le Maire, (Eds) 2003. Cost 341 Habitat Fragmentation due to Transportation Infrastructure. Wildlife and Traffic: A European Handbook for identifying Conflicts and Designing Solutions. European Co-operation in the Field of Scientific and Technical Research. Table 1 – Number of road-kills of species of conservation concern. * based on IUCN criteria (2004), VU - vulnerable, NT – Near Threatened, DD – Data Deficient.  Langevelde, F.V. & Jaarsma, C.F. 2004. Using traffic flow theory to model traffic mortality in mammals. Landscape Ecology, 19: 895–907.  Malo, J. E., Suárez, F. & Díez, A. 2004. Can we mitigate animal-vehicle accidents using predicitve models? Journal of Applied Ecology, 42: 701-710.  Pargana, J.M., O. Paulo & E. Crespo. 1996. Anfíbios e Répteis do Parque Natural da Serra de S. Mamede. Parque Natural da Serra de S. Mamede e Instituto da Conservação da Natureza, Portalegre.  Peris, S. J. & Pescador, M. 2004. Effects of trafic noise on passerine populations in Mediterranean wooded pastures. Applied Acoustics, 65: 357-366. Seiler, A. 2003. The toll of automobile. Wildlife and roads in Sweden. Annex IV. Spatial models to predict moose-vehicle collisions in Sweden. Silvestria 295. PhD Thesis. Department of Conservation Biology, Swedish University of Agricultural Sciences, Uppsala, Sweden. Trombulak, S.C. & Frissell, C.A. 2000. Review of Ecological Effects of Roads on Terestrial and Aquatic Communities. Conservation Biology, 14 (1): 18-30. Specie Year Portuguese red book* Common name Scientific name 95-97 2005 Balearic false smooth snake Macroprotodon cucullatus - 1 VU Black-shouldered Kite Elanus caeruleus 2 - NT Natterer's bat Myotis nattereri - 1 VU Greater horseshoe bat Rhinolophus ferrumequinum 1 - VU European rabbit Oryctolagus cuniculus 12 13 VU Cabrera vole Microtus cabrerae 3 - DD Polecat Mustela putorius 4 3 NT Vertebrate road-kills in 1996 0 10 20 30 40 50 60 70 1234567 8 9 101112131415161718192021222324252627 Road section km Road-kills Vertebrate road-kills in 2005 0 10 20 30 40 50 1234567 8 9 101112131415161718192021222324252627 Road section km Road-kills Vertebrate road-kills in 96 0 20 40 60 80 100 120 140 160 11-01-1996 25-01-1996 09-02-1996 23-02-1996 07-03-1996 22-03-1996 03-04-1996 18-04-1996 02-05-1996 16-05-1996 30-05-1996 13-06-1996 27-06-1996 11-07-1996 25-07-1996 08-08-1996 22-08-1996 05-09-1996 19-09-1996 Sampling session Road-kills Vertebrate road-kills in 2005 0 10 20 30 40 50 60 12-01-2005 26-01-2005 09-02-2005 23-02-2005 09-03-2005 23-03-2005 06-04-2005 20-04-2005 04-05-2005 18-05-2005 31-05-2005 15-06-2005 29-06-2005 13-07-2005 27-07-2005 10-08-2005 24-08-2005 07-09-2005 21-09-2005 Sampling session Road-kills Mortality by vertebrate class in 2005 60; 13% 45; 9% 266; 56% 104; 22% Amphibians Reptiles Birds Mammals Mortality by vertebrate class in 1996 171; 36% 60; 12% 205; 43% 45; 9% Amphibians Reptiles Birds Mammals A Fig. 2 – Percentage and number of vertebrate road-kills in each class between January and September 1996. Fig. 3 – Percentage and number of vertebrate road-kills in each class between January and September 2005. Fig. 4 – Number of vertebrate road-kills in each sampling session between January and September 1996. Fig. 5 – Number of vertebrate road-kills in each sampling session between January and September 2005. Fig. 6 – Number of vertebrate road-kills in each road section km between January and September 1996. Fig. 7 – Number of vertebrate road-kills in each road section km between January and September 2005. Conclusion Our study support the notion that the traffic flow can adversely affect certain vertebrates species, specially mammals. Also other variables, like biota and topography, should explain road mortality. Furthermore other variables such as speed velocity, width of the road, presence of culverts and retention time could be important factors in road mortality (Seiler, 2003; Langevelde and Jaarsma, 2004). So they must be study in the future. 0 1000 2000 3000 4000 5000 6000 7000 8000 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Number of vehicles 1996 2004 Fig. 8 – Traffic flow in number of vehicles per month and year in the study area There is a big difference between the results in the two periods of this study (figs. 2, 3, 4, 5, 6 and 7), specially when we compared the mammals and amphibian mortality. Also the total number of road-kills for species with conservation concern (table 1), has reinforced (here we compare all data). In both periods, the road-kills were higher in the first 10 km, where about 80% of the total road-kills occurred. Traffic volume is 2.5 times higher in 2004 (we assume no significant difference for this variable between 2004 and 2005) than it was in 1996 (fig. 8).