Effects of Off-Road Vehicle Noise on Desert Vertebrates

With the increase in the human population in Southern California and the concomitant increase in the use of open spaces for recreation, it has become clear that the activities of off-road vehicles (ORVs) are causing considerable damage to the California deserts. Associated with this use is the spread of high-intensity sounds into formerly quiet desert regions, which suggest that these sounds might have severe impacts on the wildlife in the desert. Some initial studies done before and after motorcycle races indicated increases in the aggressive behavior of kangaroo rats (Dipodomys sp.) after a race passing through an area and the observation that many of the Dipodomys had bloody ears following the race. Following this, Bondello (1976) showed that excessive off-road motorcycle sounds (115 dB A) could damage the acoustical sensitivity of desert iguanas (Dipsosaurus dorsalis).