Populations of spur-thighed tortoises (Testudo graeca), a species classified as vulnerable and at risk of extinction, can withstand fires if outbreaks occur once every three decades or more. However, the youngest tortoises are more vulnerable, and disappear after each fire. These are the results of a study by Spanish researchers, who analysed the impact of a 2004 forest fire in the Sierra de la Carrasquilla mountains in Murcia (Spain) on these reptiles.
"Tortoises can withstand high temperatures, but this does not mean their shells are completely fire proof", Ana Sanz-Aguilar, lead author of the study, tells SINC. Currently a postdoctoral scholar at the Centre for Functional and Evolutionary Ecology in Montpellier, France, she collaborated with the Miguel Hernndez University (UMH) and the Mediterranean Institute for Advanced Studies (IMEDEA-CSIC) for this research.
One such forest fire occurred on 1 August 2004 in the Sierra de la Carrasquilla mountains in Murcia, Spain, which incinerated a 250-hectare area that was home to a large population of these reptiles. The researchers have been studying the behaviour of more than 1,000 of the animals over the past decade.
The study, published in the journal Biological Conservation, shows that the tortoises' response to fire varied greatly according to their age, with the fire killing 100% of the animals aged under four and causing increased mortality rates of 62% in sub-adults (aged from 4 to 8) and 12% in adults (over 8 years of age).
"For the dynamics of this species, a 12% increased mortality rate among adults is more serious than the disappearance of all the young tortoises", says Sanz-Aguilar.
According to the study, the viability of populations of these animals depends on low mortality rates and longevity among adult individuals. Any factor that causes an increase in adult mortality, such as greater vulnerability to forest fires in rocky environments,
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