Turtles outsmart rapid environmental change: The role of cognition in navigation

Abstract

Animals inhabiting changing environments show high levels of cognitive plasticity. Cognition may be a means by which animals buffer the impact of environmental change. However, studies examining the evolution of cognition seldom compare populations where change is rapid and selection pressures are strong. We investigated this phenomenon by radiotracking experienced and naïve Eastern painted turtles (Chrysemys picta) as they sought new habitats when their pond was drained. Resident adults repeatedly used specific routes to permanent water sources with exceptional precision, while adults translocated to the site did not. Naïve 1–3 y olds from both populations used the paths taken by resident adults, an ability lost by age 4. Experience did not, however, influence the timing of movement or the latency to begin navigation. This suggests that learning during a critical period may be important for how animals respond to changing environments, highlighting the importance of incorporating cognition into conservation.

Pharmacological evidence is consistent with a prominent role of spatial memory in complex navigation

“…The precision of the routes suggests that turtles use a fine-scale, ground-based cue when learning to navigate [22,23]. Although the information used to learn navigation routes is probably multimodal, previous studies in reptiles suggest vision or olfaction as possibilities [24][25][26][27][28][29][30], and our own work suggests that aspects of UV vision might facilitate learning the navigational routes [22].…”

“…[22,[31][32][33][34][35]), particularly in reference to movements, orientation and navigation (e.g. [23,29,34,[36][37][38][39]), learning (e.g. [22,31,35]), and spatial memory (e.g.…”

“…We used radiotelemetry to investigate the means by which turtles navigate to alternative aquatic sites after the draining as per our previous work [22,23]. We captured turtles using baited hoop traps and basking traps, and fitted them with radiotransmitters (models RI-2B or BD-2, Holohil Systems, Ltd, Ontario, Canada, less than 4.5% body mass).…”

“…Naive turtles must navigate this site prior to age 4 to be able to successfully navigate as adults [22,23]. The precision of the routes suggests that turtles use a fine-scale, ground-based cue when learning to navigate [22,23].…”

“…In our system, turtles are forced to navigate terrestrial habitat after annual aquatic habitat loss. Animals in our focal population locate far-off, permanent water sources using one of four very precise (+3.5 m), highly predictable routes (animals use the same routes year after year; figure 1) [22,23].…”