Engineering rodents create key habitat for lizards

There is growing recognition among ecologists that ecosystem engineers play important roles in creating habitat for other species, but the comparative and combined effects of co-existing engineers are not well known. Here, we evaluated the separate and interactive effects of two burrowing rodents, Gunnison's prairie dogs (Cynomys gunnisoni) and banner-tailed kangaroo rats (Dipodomys spectabilis), on lizards in the Chihuahuan Desert grassland (USA). We found that the mounds and burrow systems of both rodent species provided important habitat for lizards, with lizard abundance being 2 to 4-fold higher on mounds than in adjacent areas without mounds. Kangaroo rat mounds supported greater numbers of lizards than prairie dog mounds, but the prairie dog colony with kangaroo rats supported 2-times more lizards than the landscape with only kangaroo rats. A greater number of mound habitats were available for lizards where prairie dogs and kangaroo rats co-occurred, and the rodents created unique structural mound types with different spatial distributions on the landscape. Our results demonstrate the importance of burrowing rodents in creating habitat for other animals, and that the combined effect of ecosystem engineers, especially those with large ecological roles, can be complementary and additive in areas where they co-occur.