Threats to Wild Tortoise Populations: Biological Pollutants & Hybridization

1. Biological Pollutants: Why Can’t We Release Captive Tortoises? How good intentions of releasing captive tortoises threatens wild populations Hybridization: Upper Respiratory Tract Disease (URTD): Mycoplasma agassizii • Mojave and Sonoran populations are physically separated by the Colorado River. • Modern transportation has helped facilitate mixing of individual tortoises across populations. • Cross breeding of populations threatens the integrity of the species and may put original population at risk. • Introduction of URTD has caused significant population declines in the Mojave region, via the release of infected captive tortoises into the wild. • Symptoms include discharge from nose and eyes (above photo), swollen eyes and wheezing. • Once contracted, URTD stays with tortoises their entire lives. Recurring symptoms can be stress-related, due to prolonged drought and human interference. Displacement: • Released captive tortoises can displace or disrupt areas already occupied by other wild tortoises. • Introduced individuals compete for burrow space, food and other resources. • Urbanization and fragmentation of natural habitat allows for more interaction between captive and wild tortoises. References: • Jones, C., et al, 2005. Mycoplasma agassizii in desert tortoises: Upper respiratory tract disease in captive and free-ranging populations in greater Tucson, Arizona. Final report to the Arizona Game and Fish Department, Phoenix, AZ. • www.azgfd.gov/w_c/deserttortoisemanagement.shtml Photo by Paul Condon Desert Tortoise Research: The University of Arizona is researching the effects of urbanization on URTD and wild desert tortoise populations. It is illegal to release a captive tortoise into the wild! Emily Kaleugher, Nov. 7, 2009