Endangered Species Issues along the Colorado River

   As you undoubtedly know, there are several threatened and endangered species that call the Colorado River their home for at least part of the year. They include the Bald Eagle, Peregrine Falcon, Kanab Ambersnail, Southwestern Willow Flycatcher, Humpback Chub, and possibly the Razorback Sucker. These species are all at potential risk from human recreation impacts associated with camping, river running, fishing, hiking, and exploration. Grand Canyon river guides play a very important role in educating visitors and protecting natural and cultural resources along the river. Because of your important role, I thought it would be a good idea to give you some background information about some of these species and also present you with a summary of measures that Grand Canyon National Park is recommending to eliminate negative impacts from human visitation.

   The regulation to protect humpback chub remains in place at the lcr; it prohibits fishing and camping within 1/2 mile of the mouth. The following restrictions on visitation and recreation are also in place to protect two other endangered species that occur along the Colorado River, the Kanab Ambersnail and the Southwestern Willow Flycatcher.

   This small brownish flycatcher species was listed by the U.S. Fish and Wildlife Service as an endangered species in February, 1995. It nests in tamarisk and willow dominated riparian vegetation below the old high water mark along the Colorado River. Most nests are placed in branches less than 20 feet in height and are therefore at risk from disturbances associated with hiking and camping within the riparian zone. Camping restrictions were put in place along the river during past years to protect these sites from human disturbance during the breeding season. The following areas will be closed to all recreational use between May 1 and July 15, 1995:

   Mile 50-52 river left (above Little Nankoweap)

   Mile 71 river left (Cardenas Marsh)

   These sites and closure intervals are based on nesting monitoring surveys that have been conducted for Southwestern Willow Flycatchers between mid-May and Mid-July in 1993 and 1994, and represent places where breeding birds were found. Surveys will be conducted again in 1995 and, if additional birds are found at other sites this year, additional use restrictions will be put in place until the breeding season ends in July. When camping or stopping in other places along the river, please use care when moving through tamarisk/willow vegetation to avoid damaging nests or disturbing nesting flycatchers and other birds.

   Kanab Ambersnails are currently known to exist only at Vasey’s Paradise and one other site in Southern Utah. The snails occur within the poison ivy/monkeyflower vegetated area at Vasey’s among dead plant matter, but do not seem to use the bare rock habitats. The shell is a mottled gray and light amber color, about 1” in length, and easily overlooked in the field. Population numbers are not known definitively and will be determined more precisely this year, but are thought to number less than 2,000 individuals at Vasey’s.

   The park is requesting that guides restrict human use at Vasey’s Paradise only to the narrow zone of bare rocks that lies between the water’s edge and upwards to within 5 feet of the vegetated area below the Redwall spring outpours (i.e. no person should approach the vegetated area closer than 5 feet). This is aimed at preventing people from inadvertently stepping on snails while tromping into the vegetated area. The vegetated area represents habitat that is critical to the snail’s survival. If people stay at the water’s edge to collect drinking water and photograph the site, it is anticipated that human-snail conflicts will be avoided. The park will be monitoring the voluntary compliance this year and, if it works, it will not be necessary to close the site to visitation altogether.

Thank you for the very important role you play in protecting resources along the river.

Jim Petterson
Wildlife Biologist
Grand Canyon National Park