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Shell-skeletal Remains of Gopherus agassizii Collected at the 7.77 square km plot at the fenced Desert Tortoise Research Natural Area in 1985, 1989-1993, 1997-2002, and 2012.

Dates

Publication Date
Start Date
1980
End Date
2012

Citation

Berry, K.H., 2021, Demography and habitat of desert tortoises at the Desert Tortoise Research Natural Area, western Mojave Desert, California (1978 - 2014): U.S. Geological Survey data release, https://doi.org/10.5066/P9BY0HVH.

Summary

The database on shell-skeletal remains from 1980 through 2012 was collected as part of a monograph covering the desert tortoise populations inside and outside the fenced Desert Tortoise Research Natural Area during a period of population decline. The principal objectives of the study were to compare trends in demographic and habitat data inside the protective fence with those outside the fence. Populations and habitat outside the fence were unprotected from recreational vehicle use and sheep grazing. Data for each shell-skeletal remain found on the long-term, 7.77 square kilometers plot, included carcass number, previous number as a live tortoise, date of collection, date last observed if marked; known or estimated size, and sex, amount [...]

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Shell-skeletal remains for DTRNA.csv 38.45 KB text/csv

Purpose

These data were an essential part of determining drivers of decline in desert tortoises for the research project and for publication. Specific objectives included but were not limited to critical demographic and management information, such as (1) identification of dead, marked individuals by size, age class, and sex for calculation of death rates and annualized mortality rates; (2) potential and known causes of death, e.g., by predator, disease, or human-caused (vehicles, shooting); (3) estimated time since death for each individual; and (4) location with respect to the fence. Land and wildlife managers are particularly interested in actions that can be taken to reduce losses to a federally- and state-listed threatened species.

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Communities

  • USGS Western Ecological Research Center

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