Road House

Stretches of shrubs and other greenery along highways can provide habitat to small mammals that are being forced out by the expansion of farms, researchers have found.

The problem is acute in the Mediterranean Basin, an area rich in wildlife that has been degraded by livestock. These animals graze and trample the land, leaving it “reduced to bare ground devoid of vegetation,” the study authors write in Biodiversity and Conservation. Small mammals such as mice have a hard time burrowing through the packed soil and are more likely to be spotted by predators.

The team investigated whether green stretches along the edges of highways, called verges, might offer these mammals refuge. In 2008, the researchers captured mice and shrews at the verges of two highways in southern Portugal. They also caught small mammals in nearby areas called “montado,” used for livestock grazing and growing trees and crops, and in open croplands or fallow sites.

The team ended up capturing 355 animals, including 252 mice and 99 shrews. Highway verges had bigger, denser shrubs and more small mammals than the montado and open sites, the researchers found. Wood mice, for example, were common in highway verges near montado but rarely found in montado or open areas. “Our findings show that highway verges can be important habitat for small mammals within intensively livestock used Mediterranean landscapes,” the team writes.

Fences along the verges appeared to help plants grow, which then offered shelter for small mammals. One downside is that more predators may start hunting mice and shrews along highways and risk getting hit by cars, so managers will need to take steps to keep those larger animals out. Roberta Kwok | 6 November 2012

Source: Ascensao, F. et al. 2012. Highway verges as habitat providers for small mammals in agrosilvopastoral environments. Biodiversity and Conservation doi: 10.1007/s10531-012-0390-3.

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