Birders will find that half the known breeding species in North America have been spotted at San Pedro. Besides birdwatching , hiking , camping , wildlife viewing , photography , seasonal hunting , horseback riding , nature study , and environmental education are popular. San Pedro is also a great place to explore archeological sites of the prehistoric Clovis people and historic ruins from the days when the Spanish, Mexicans, and U.S. were moving into the area. The San Pedro River enters Arizona from Sonora, Mexico, flows north between the Huachuca and Mule mountain ranges, and joins the Gila River 100 miles downstream near the town of Winkelman. The San Pedro's perennial flow, though sometimes a trickle, is a rare occurrence in the Southwest.
Water is the critical element in a riparian ecosystem.
Without an adequate, continuous supply, the ecosystem would perish. The San Pedro Riparian National Conservation Area, known for its extensive riparian corridor, is a composite of several vegetation communities. Fremont cottonwood and Goodding willow dominate the riparian corridor. Lesser amounts of Arizona ash and walnut, netleaf hackberry, and soapberry occur as well. Chihuahuan desert-scrub, typified by thorny species such as tarbush, creosote and acacia, characterize the uplands bordering both sides of the river, while mesquite and sacaton grass dominate the bottomland adjacent to the riparian corridor.