Before the 1996 and 1997 inventories, the most recent bat species list (1978) compiled for the river corridor included only seven species. Survey methods used in the 1998 follow-up inventory included traditional mist netting, use of harp traps, and cave exit counts, in addition to the Anabat system. This technique, which employs a bat detector that transforms ultrasound to an audible output, enables users to identify bat species. Through this combination of methods, the 1998 surveys more than doubled the 1978 figures by adding nine new species, including spotted, silver-haired, hoary, western mastiff, Mexican long-tongued, red, and big free-tailed bats.
Monitoring of cave populations of Townsend’s big-eared bats, western mastiff bats, and Mexican free-tailed bats has proven crucial in the recovery of these maternity and roosting colonies. Surveys detected declines in, or a complete absence of, populations that are known to have existed in cave systems throughout the park. In 1996 the park erected a bat-navigable gate over the entrance to Stanton’s Cave, the location of a maternity roost of Townsend’s big-eared bats that had been repeatedly disturbed by years of archeological excavations and visitor day-use. The population has since recovered from just a few individuals to nearly 80! Monitoring plans for 1999–2000 include collecting more data on migratory species such as the Mexican free-tailed bat. Grand Canyon National Park hosts the largest colony of this species in Arizona, and although the park affords habitat protection during the breeding season for this migratory species, little is known about the habitat in Mexico upon which it depends for overwintering. Future plans include looking beyond park boundaries with the goal of securing partnerships for the preservation of overwintering habitat.
The Grand Canyon surveys and monitoring efforts have yielded not only invaluable information but also a wide range of concerns. The park provides abundant roosting and foraging habitat for bats, from extensive cave and fissure systems to old-growth forest; however, recreationists prefer the same areas favored by bats. Thus, the disturbance of critical habitat is being addressed in the implementation of various park management plans (e.g., Colorado River Management Plan, Cave Management Plan, and Backcountry Management Plan). Future monitoring of bat populations and distribution, and analysis of the new baseline, will enable resource managers to recommend sound management actions.
In continuing efforts to protect the world’s resources, nothing is more important than transforming data into knowledge. Communicating this knowledge to an informed and supportive public will afford the best long-term protection and preservation of sensitive natural resources, including the bat species of Grand Canyon National Park.
elaine_leslie@nps.gov
Wildlife Biologist, Grand Canyon National Park, Arizona
NEOTROPICAL MIGRANTS
Forty round-trip plane tickets were donated to the National Park Service by American Airlines in 1998 to promote dialogue among park managers in Latin America and the United States. Resource managers now have a better chance of meeting face-to-face to coordinate strategies for the protection of wintering and breeding habitats of long-distance migrants such as birds and bats. An ad campaign for the airline will publicize the complex international conservation issue regarding Neotropical migrants by stating, “Everyone needs a place to land.”
Back to Chapter 2: NPS Science
Shoreline studies at Padre Island point to trash sources
by John Miller
White abalone: Going, going, gone?
by Gary E. Davis
Riparian monitoring focused on stream recovery in Canyonlands
by Charlie Schelz
Science-based planning at Tallgrass Prairie National Preserve
by John Neal and George Oviatt
Recurrent themes of water resources management plans
by David L. Vana-Miller
Program Center takes on geologic inventories
by Bruce Heise and Joe Gregson
Survey research provides management information
by Jean E. McKendry