Roads, highways, railroad, and utility corridors have the potential to be detrimental to some wildlife. They fragment habitats and landscapes (Reed et al. 1996, Saunders et al. 1991) dividing large landscapes into smaller patches and converting interior habitat into edge habitat. Studies in other states have demonstrated negative correlations between increasing road densities and wildlife populations (Lee et al. 1997, Wisdom et al. 2000).
New Mexico has over 206,000 miles (33,152 km) of major and minor roads, including US Forest Service classified roads (Earth Data Analysis Center, RGIS Tiger Data: http://edac.unm.edu/). A 16 foot-wide road removes approximately two acres of habitat per mile of road. Accident report data compiled by the University of New Mexico documented 914 large game animal/vehicle collisions in 2002 in New Mexico. An annual average of 828 large game animal/vehicle collisions has occurred since 1998 (Forman et al. 2003). Since many incidents go unreported, this number represents only a fraction of the total large animal/vehicle collisions that actually occur annually. In addition to collisions with vehicles, roads facilitate legal and illegal killing and collection of many large and valuable animals. In the US Forest Service's Southwestern Region, 57% of threatened, endangered and proposed species under the federal Endangered Species Act, and 54% of US Forest Service's Sensitive Species are dependent on habitat within or affected by Inventoried Roadless Areas (IRAs) (US Forest Service 2000).
Roads and similar structures influence stream characteristics, such as channel and floodplain configuration, substrate embeddedness, riparian condition, amount of woody debris, stream flow, and temperature regime (Furniss et al. 1991). Timing of water runoff can change as roads and related drainage structures intercept, collect, and divert water. These factors can accelerate water delivery, resulting in an increase in the potential for greater magnitude of runoff peaks than in watersheds without roads (Wemple et al. 1996). Roads, highways, railroad, and utility corridors serve as a means of dispersal for many non-native and invasive plant species. Ground disturbance associated with the creation and maintenance of these facilities provides additional opportunities for establishment of non-native species (Parendes and Jones 2000).