Carnivores more seriously threatened by roads than previously acknowledged
The effects of roads on carnivores have obviously been underestimated in worldwide species conservation. This is the conclusion of the first comprehensive global study on this topic, which has been published in the scientific journal Global Ecology and Biogeography by an international research team from Germany and Portugal. The protection status of several species that are severely affected by roads cut through their habitat should be reconsidered, the researchers say.
|The brown bear (Ursus arctos) is among those carnivore species that are most exposed to roads globally. Its current |
protection status should be reconsidered, the study authors say [Credit: bodsa/Pixabay]
Particularly under threat is the Iberian lynx (Lynx pardinus), which lives only in Spain and Portugal; according to estimates, only a few hundred animals remain. The projection in the current study suggests that the species will have died out in 114 years. But while the Iberian lynx is IUCN-classified as "endangered", other species threatened by roads are not. For example, two species in Japan: According to the projection, the Japanese badger (Meles anakuma) and the Japanese marten (Martes melampus) will have died out in nine and 17 years, respectively, because of the threat from roads.
|The researchers were surprised to find that also the stone marten (Martes foina) belongs to the carnivore species most |
affected by roads. The species is widely distributed, but often killed by cars [Credit: Mike aus dem Bayerwald]
For their study, the researchers considered a total of 232 carnivore species around the world (out of a total of ca. 270 existing species) and assessed how severely these are affected by roads cut through their habitat. To do this, they considered for example the natural mortality rate, the number of offspring and the movement behaviour of a species. From these factors, they calculated the maximum density of roads that a species can cope with. Furthermore, they determined the minimum area of unbroken habitat that a species needs to maintain an enduring healthy population. Finally, they compared these numbers with road network data.
|Another species in Germany, the wolf (Canis lupus) is among the top 25% of species most exposed |
to roads worldwide [Credit: raincarnation40/Pixabay]
In Africa, for example, roads have a significant effect on the habitats of leopards (Panthera pardus). This is because sensitive species that naturally cover greater distances can be restricted by comparatively few roads. "We did not simply lay roads and habitats of species over one another, but also considered the specific characteristics and requirements of the species in our calculations. In this way we could also identify species that react sensitively to even only a few roads," says Ceia-Hasse. The methods established in the new study can be used in future for applied purposes - for example for local protection measures, for environmental assessments by authorities, or to integrate the long-term effects of road building into scenarios of the World Bank regarding global biodiversity changes.
Source: German Centre for Integrative Biodiversity Research [February 08, 2017]