Restrictions on roaming Until the past century or so, the movement of wild animals was relatively unrestricted, and their travels contributed substantially to ecological processes. As humans have increasingly altered natural habitats, natural animal movements have been restricted. Tucker et al. examined GPS locations for more than 50 species. In general, animal movements were shorter in areas with high human impact, likely owing to changed behaviors and physical limitations. Besides affecting the species themselves, such changes could have wider effects by limiting the movement of nutrients and altering ecological interactions. Science , this issue p. 466

Although facultative scavenging is very common, little is known about the factors governing carrion acquisition by vertebrates. We examined the influence of carcass characteristics, carcass state, and weather conditions on carrion use by main scavengers. Carcasses (N = 214, mainly ungulates) of various origins (predation, natural deaths, harvest) were monitored by systematic inspections (N = 1784) in Białowieża Forest (Poland). Common raven (Corvus corax L., 1758), red fox (Vulpes vulpes (L., 1758)), and European pine marten (Martes martes (L., 1758)) mainly used the prey remains of gray wolves (Canis lupus L., 1758). The kills of predators were the preferred carrion, rather than dead ungulates. Common ravens, common buzzards (Buteo buteo (L., 1758)), white-tailed eagles (Haliaeetus albicilla (L., 1758)), and domestic dogs scavenged more frequently on carcasses in open habitats. Carcasses located in the forest were the most available to European pine martens, jays (Garrulus glandarius (L., 1758)), and wild boar (Sus scrofa L., 1758). The common tendency was to increase scavenging when temperature decreased, except for raccoon dogs (Nyctereutes procyonoides (Gray 1834)). As snow depth increased, jays and great tits (Parus major L., 1758) increased scavenging. We suggest that carrion use by scavengers is not random, but a complex process mediated by extrinsic factors and by behavioural adaptations of scavengers.

Roads fragment landscapes and trigger human colonization and degradation of ecosystems, to the detriment of biodiversity and ecosystem functions. The planet's remaining large and ecologically important tracts of roadless areas sustain key refugia for biodiversity and provide globally relevant ecosystem services. Applying a 1-kilometer buffer to all roads, we present a global map of roadless areas and an assessment of their status, quality, and extent of coverage by protected areas. About 80% of Earth's terrestrial surface remains roadless, but this area is fragmented into ~600,000 patches, more than half of which are <1 square kilometer and only 7% of which are larger than 100 square kilometers. Global protection of ecologically valuable roadless areas is inadequate. International recognition and protection of roadless areas is urgently needed to halt their continued loss.