Road Ecology Center

In the 1900‘s, the badger population of the Netherlands was estimated to count 2500 to 3000 setts with over 4000 individuals. Between then and the 1960‘s, the number declined drastically and stayed low until the mid-1980‘s with about 400 setts in the whole of the Netherlands. In the 1980‘s a high percentage of the population, locally up to 25%, was killed yearly by road traffic. For this reason the Dutch government implemented mitigation measures such as fauna tunnels and fences. It was easy to monitor the use of such measures. By census we know that the population increased to around 5000 individuals in 2006. But were these “badger tunnels” effective: did the number of traffic victims at these tunnels decrease?

To answer this question we analyzed data on badger traffic victims gathered by NGO Das & Boom and the Center for Transport and Navigation (Rijkswaterstaat) between 1990 and 2006. First, we determined the distribution of victims over motorways, provincial roads and local roads. In absolute terms, most victims were reported from local roads. However, relative to the length of road in the range of the badger, most victims occur at provincial roads.

Second, we tested whether taking mitigating measures resulted in a decrease of traffic victims. Realization of fauna tunnels resulted in a small but significant decrease in the local number of victims, but effects varied from site to site: at most sites, the number of victims was lower, but at some the number of victims was higher after implementation of the measure. Analysis on a local scale should provide a clearer picture of the effect of mitigation measures on badger mortality. Such a study was done in the area ‘Eindegooi’ where the increase of the population of badgers is spectacular. It appears that the increase is related to a package of measures taken in that area.

The challenge for conservation now lies in minimizing victim numbers at local roads. As badger victims occur over a huge length of local roads, mitigation will be difficult. Still, a number of measures are feasible, for example locally designed tunnels and fences, decreasing speed limits or closing roads for through traffic, especially at ‘black spots’ with high numbers of victims.