Road Density as a Factor in Habitat Selection by Wolves and Other Carnivores in the Great Lakes Region

Although wolves (Canis lupus) and many other carnivores are habitat generalists, certain landscape features can be used to predict suitable habitat. Thiel examined the concept of road density as an important factor in the persistence of wolf populations in Wisconsin prior to the 1960s and found a relationship with the disappearance of breeding wolf populations when average road density exceeded 0.58 km/km. Mladenoff and colleagues examined road density in the early 1990s as a factor in predicting favorable habitat of wolves colonizing Wisconsin between 1980 and 1992, and found that areas with road densities less than 0.45 km/km had greater than a 50% probability of being colonized by wolf packs. Mladenoff and colleagues updated this work in the late 1990s by examining 23 packs colonizing Wisconsin between 1993 and 1997; 78% continued to occupy areas with road densities below 0.45 km/km. In a recent examination of radio-collared wolves in Wisconsin, a total of 60% of human-induced mortality occurred at road densities above 0.63 km/km. Although road density may become less of a factor as human tolerance changes, and wolf populations increase, it continues to be an important factor in habitat selection by wolves and probably other carnivores.