Roads have important effects on wildlife, such as natural habitat fragmentation and degradation and direct killing of fauna, which leads to reductions in wildlife population size. We focused on a principal road in Northwest Argentina to test for the effect of seasonality and landscape features on the composition of road-killed wildlife. We conducted regularly scheduled road trips during the dry and wet seasons. We recorded the presence or absence of a vegetation curtain or hedge along the road. We measured land use by remote sensing in a 500 m buffer along the road. We compared the abundance of animals killed between seasons (dry and wet) for different taxonomic groups (mammals, birds and reptiles) and for different origins (domestic and native). We built linear mixed models to test the effect of landscape features on the abundance of killed animals. Two hundred and ninety-three individuals were killed, belonging to 35 species; 75.8 % were native and 24.2 % domestic species. The majority of animals killed were mid-sized mammals. More animals were killed during the dry season. The most important factors to explain the wildlife road-killing were the season and the proportion of agricultural landscape. The composition of the killed animals changed with the season. The proportion of agricultural landscape incremented the number of killed birds and mammals during both seasons, without affecting reptiles. The ratio of wild to domestic animals killed was dependent on the season. This study sets a precedent as the first in road ecology in Northwest Argentina and should be taken into account for road planning and regulation.

Question: Is domestic cattle an appropriate surrogate for fire in a protected humid temperate savanna? Study area: El Palmar Grande de Colón (31º52´ S, 58º17´ W), Argentina. Methods: We surveyed dense Butia yatay palm savannas in two neighboring protected areas, El Palmar National Park (EPNP), under cattle exclusion since 1970 with sporadic burning; and La Aurora Wildlife Refuge (LAWR), under moderate cattle density, and not burnt since 1997. In each area, we randomly selected ten dense savanna stands, established 500 m² plots and undertook floristic survey in spring and summer to produce exhaustive plant-species lists. We statistically compared the two samples in terms of: local and global diversities; compositional heterogeneity among stands; mean similarity to a historical record from the area; overall species composition; and abundance and numbers of species with different growth habits and origins. Results: Differences between our samples are clear-cut. Savannas at EPNP have significantly increased local and global species richness and exhibit decreased similarities with the historical record. They have a novel understory, with significantly increased abundances and species numbers of fire-resistant grassland shrubs and fire-sensitive trees, and a groundcover with significantly increased richness of subshrub and perennial graminoid species. Savannas at LAWR have virtually no woody understory, and exhibit a groundcover dominated by an impoverished suite of perennial grasses, with significantly increased abundances and numbers of annual and of exotic species. Conclusions: Our results suggest that large-scale, long-term cattle exclusion and sporadic fires have resulted in changes in the structure and composition of the savanna vegetation leading to increased plant species diversity. Apparently, conservation of these humid savannas in protected areas requires periodic fire, while domestic cattle are a poor alternative for maintaining their plant species diversity.

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