People seldom see cougars, America’s largest wild feline, because of the cats’ secretive ways. But their skittishness comes at a cost, says a team of researchers who tracked the movements of 30 cougars in California’s Santa Cruz Mountains between 2008 and 2013. The researchers fitted the cats with GPS and radio collars, then used a special software program to identify 208 sites to which the cougars (Puma concolor) returned over the course of several days—a sign that they likely had made a kill. In urban areas with between two and nine houses per hectare, female cougars killed 36% more deer than female cats in rural areas and spent less time feeding on each carcass, the scientists report online today in the Proceedings of the Royal Society B. Male hunting patterns did not appear to be affected. The findings suggest that female cougars expend more energy hunting in urban areas and may be paying a price in terms of reproductive success, the researchers say. They note that one of their collared females has lost three of her litters in the last 3 years—and she lives in the most developed habitat.