In this study, we analyzed the effect of body temperature on
righting behavior of two species of freshwater turtles which actively
bask aerially: the Spanish terrapin (Mauremys leprosa) and the
red-eared slider (Trachemys scripta elegans). The Spanish terrapin
is widespread in the south and central Iberian Peninsula and northwestern
Africa [18]. However, this species has suffered a considerable
recession during the last few decades, being currently
considered as an endangered species [19]. Besides habitat destruction
and human pressure, the remaining populations must endure
competition with exotic introduced turtles, mainly American sliders
[20–22]. Although the nature of the interspecific interactions between
native and introduced turtles is not completely clear, recent
studies have highlighted diverse competitive advantages of sliders
over Spanish terrapins, such as a more accurate assessment of predatory
risk in altered habitats, displacement of native turtles mediated
by chemical cues avoidance, a greater thermal inertia that favors
heat retention and digestive processes or more competitive basking
and feeding abilities [23–28]. Both M. leprosa and T. scripta turtles
are predominantly aquatic, but they come onto land for activities
such as basking or egg-laying [29,30]. In such vulnerable situations,
turtles are extremely alert and vigilant, since they are potential prey
of birds and mammals [31,32]. Thus, overturning accidentally while
walking or climbing solaria, or during predatory attacks, may have
serious or even lethal consequences for turtles, if they are not efficient
at self-righting