Seasonality and habitat types affect roadkill of neotropical birds.

Roadkills are amongst the most significant biodiversity impacts, although little is known about the factors which influence the roadkill of neotropical birds. Hence, the objective was to evaluate differences in roadkill richness and rates for neotropical birds according to the seasons of the year and habitat types associated with roads. The data was collected along two federal highways, in southern Brazil. We identified 57 roadkilled species, for a mean roadkill rate of 0.06 ind./km/day (Min.=0.009; Max.=0.47). Our results demonstrate that richness and roadkill rates change according to seasonality and habitat types. Roadkills were concentrated in rice fields and wetlands, intensifying both in richness and rates during the summer and autumn. Nearby areas have similar roadkill rates, independent of habitat types. This probably occurs due to the movement of several species seeking food and shelter. Juvenile dispersion, harvest and grain transportation periods, as well as flight and foraging behaviors over road lanes seem to be related to the increasing roadkill occurrences and richness regarding more abundant species. However, given the elevated number of occasionally roadkilled species (more than 70% with N<5), we believe that highway surface and traffic act as physical barriers which inhibit the movement of many species which either present occasional roadkills or none at all. Crown