[QUOTE=Richard Parker]
Yeah, I would expect a courtship to be a display or behavior on the part of the male that is observed or received by the female.
The behavior I observed was fully mutual. Not alternating either. Just constant, mutual, splashy-splashy. Perhaps two males trying out their pick-up splash?
[/QUOTE]
I’ll speculate-- I am not familiar with the “lemur pond” described, but I’ve seen what may be similar situations at many facilities. A pond built for a specific purpose (like lemurs) may also contain turtles. Since these turtles are not the purpose of the exhibit but merely a happenstance, the pond may become the default dumping ground of additional, miscellaneous, turtles acquired over time. (The OP notes “dozens of turtles of varying species”.)
In the Emydid turtles (Family Emydidae, these “pond sliders” and some others like North American box turtles) the claw waving apparently conveys both courtship intention and some kind of species identification. While courtship of some species has been intensively studied, others remain almost unknown. We do know though that in the wild, several species of similar size and habits may inhabit the same geographic area and the same specific habitat. They literally live together in the same pond, stream, or lake. And they exhibit what to us observers appear to be identical courtship behaviors. Still, the species remain distinct with only rare hybridization. Clearly, something we are not seeing is being conveyed.
In captive situations where crowding occurs and/or where similar but not normally sympatric species are artificially brought together, most of these species turn out to be inter-fertile and hybridization becomes the norm. Apparently something in that species-specific courtship behavior is overcome or broken down by the presence of too many individuals or individuals of species that would not normally encounter each other in the wild. I’ve seen a number of such ponds/exhibits where the turtles can only be identified as generalized slider-types and few or no identifiable pure species remain.
The “claw waving” continues, but whatever its finer details (? speed or rate of waving; closeness of approach, touch or not touch; subtle color patterns exhibited or hidden ?) those details no longer serve to “turn on” the right females and “turn off” males and incorrect females. In situations like this, probably any random turtle may be viewed as a potential mate. So the males may actively engage any other turtle with these displays, including other males as well as individuals of different species. And, since neither of the individuals seems to recognize the signals that should say “quit!”, the display may be protracted.
At any rate, that’s my best guess.