Prior to congressional approval of Glen Canyon Dam in 1956, fewer than 500 people have run the Colorado River through the Grand Canyon (Lavender 1985). This is compared to today, when over 20,000 people, as part of commercial or private trips, raft the river annually. According to the commercial river guides, the number of private trips is poised to increase as the Park Service transitions from a waiting list to a lottery system, while simultaneously increasing the number of private trips being allowed on the river.
Campers, ourselves included, are highly intrusive on many, if not all, campable beaches along the river corridor. On a beach that may be half sand and half vegetation, campers tend to sniff out the most private niche to set up camp. This generally translates into the most obscure, entrenched place one can find. Usually nestled against or within a grove of trees, these “prime” camping spots are also the most precious to nesting birds. The image below is from our own trip of a beach that became crowded when tents were erected. It is easy to see how campers have an invasive presence on already crowded beaches.
The physical presence of a bright yellow tent under nesting trees may be enough to dissuade a breeding bird from placing their nest in an otherwise suitable location. The bird’s nest may therefore be placed at an inferior nesting site. Similarly, a nest may be constructed in the spring while rafter presence is low; however, as human traffic ramps up in the summer rafting season, increasing human disturbance may force birds to abandon a nest that may by then contain eggs or nestlings.
Miscellaneous disturbances such as noise, smoke or even hanging clothing from trees may all adversely impede reproductive behaviors. Although campfires are not allowed in the park between April and October, noise and other disturbances are greatest between May and September when camper densities are the highest.
The presence of rafts and people on beaches may displace roosting and/or foraging waterfowl and shorebirds. On several occasions, various waterfowl tracks were noticed on several beaches we occupied. One beach in particular had extensive Great Blue Heron tracks. At dusk, a Great Blue Heron returned and stood at a point adjacent to the beach, and remained there for the better part of an hour, as if waiting for us to leave. It eventually flew away, perhaps to find an alternative foraging area. This specific beach had a relatively large backwater area that supported many young fish, a probable foraging site for the heron.
According to several rafting guides, riparian vegetation such as tamarisk and arrowweed are colonizing camping sites, increasing the potential for disturbance between birds and campers. They propose manual removal or prescribed burns to control beach encroaching vegetation. Such removal of riparian vegetation may adversely affect nesting birds in the Grand Canyon. A compromise, however, is surely possible to optimize both riparian vegetation for birds and open sandy beaches for rafter habitat.
References
Lavender, D. 1985. River Runners of the Grand Canyon. Grand Canyon, Arizona. Grand Canyon Natural History Association.