Dog attacks on wild desert tortoises: A risk model

Journal of Wildlife Management
By: , and 

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Abstract

We retrospectively compiled a database of 6,727 live, wild Agassiz's desert tortoises (Gopherus agassizii) and evaluated them for clinical signs of trauma to shell and limbs at 50 sites in the Mojave and Colorado (western Sonoran) deserts of California, USA, spanning the years 1977–2006. Our objectives were to 1) identify tortoises with severe trauma to shell, limbs, and gular horns typically seen in attacks from dogs (Canis familiaris); 2) identify locations where severe injuries occurred; and 3) develop a risk model based on distances of tortoises from settlements, towns, or cities. Our models identified multiple variables of importance for tortoises with severe damage to shells, limbs, and gular horns: relative age and sex of tortoises, decades of occurrence, and location. Females and very old tortoises were more vulnerable to attacks than other tortoises. In the decades between the 1970s and 2000s, the risk of severe overall trauma to shell and limbs increased 4 times and to gular horns 16.5 times. Compared to previous decades, by the early 2000s the percent of tortoises with severe trauma increased exponentially the closer a tortoise site was to a settlement; the exponential increase began at approximately 12 km from a settlement. We suggest that the risks may be higher now because of the growth of human populations within the geographic range of the tortoise. The threats to tortoises from dogs are based on whether dogs are off-leash in the Mojave and Colorado deserts.

Suggested Citation

Carlson, A.S., Berry, K.H., and Mack, J.S., 2026, Dog attacks on wild desert tortoises: A risk model: Journal of Wildlife Management, e70192, 22 p., https://doi.org/10.1002/jwmg.70192.

Study Area

Publication type Article
Publication Subtype Journal Article
Title Dog attacks on wild desert tortoises: A risk model
Series title Journal of Wildlife Management
DOI 10.1002/jwmg.70192
Edition Online First
Publication Date March 16, 2026
Year Published 2026
Language English
Publisher The Wildlife Society
Contributing office(s) Western Ecological Research Center
Description e70192, 22 p.
Country United States
State Arizona, California, Nevada, Utah
Other Geospatial Colorado Desert, Mojave Desert
Additional publication details