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25th Annual Meeting and Symposium of the
Desert Tortoise Council, April 21-24, 2000
Abstracts
Implementation of Long-term Monitoring of Desert Tortoise Populations Using Line Distance Sampling Methods
Michael Burroughs1 and Bob Williams2
1U.S. Fish and Wildlife Service, Southern Nevada Field Office, Las Vegas, NV
2U.S. Fish and Wildlife Service, Nevada Fish and Wildlife Office, Reno, NV
Substantial funds are being spent on desert tortoise recovery actions yet there has not been a comprehensive program in place to determine if these actions are improving the status of desert tortoise populations or whether recovery goals are being achieved. In recognition of this need, several workshops were held to evaluate various methods to monitor tortoise populations. In 1998, the Desert Tortoise Management Oversight Group (MOG) chose line distance sampling as the appropriate method to determine rangewide desert tortoise population densities and trends. Through successful rangewide monitoring, managers will be able to evaluate the overall effectiveness of recovery actions and population responses to these actions, thus guiding recovery of the Mojave desert tortoise. Furthermore, monitoring must show that population trends are stable or increasing for a period of 20 years before delisting may be considered. Following delisting, section 4(g) of the Endangered Species Act requires the Fish and Wildlife Service (Service) to monitor the status of all recovered and delisted species for a minimum of 5 years.
The Service is in the process of hiring a rangewide desert tortoise coordinator with primary responsibility to oversee implementation of desert tortoise population monitoring activities. Because a consistent approach to monitoring is essential, a monitoring plan or set of field protocols will be developed to standardize methods. Transects established and read as part of pilot studies will continue, which should provide important data to further define the monitoring strategy required to produce reliable density estimates. After 5 years of having the recovery plan in place, we have made little progress at implementing rangewide monitoring, largely due to lack of funding. In response to this need, the technical advisory committee of the MOG recommends establishing recovery implementation teams representing each of the recovery units. These teams will develop budget requests and prioritize research needs in cooperation with the coordinator which will be submitted to the MOG for approval and action.