Like bumper-to-bumper rush hour in Dallas.
Even if temperatures are cool bordering on cold, a sunny day brings the turtles out en masse. Any perch above the water becomes a turtle logjam.
The species can be quite diverse, from softshells to cooters to sliders to anything else that finds room.
And when there’s no more room on the log, there’s always room to climb atop another turtle.
Everyone gets along if everyone gets some sunshine.
And if you’re lucky, you can find synchronized sunning like this pair, both of whom have their back legs stretched out and their heads held up.
— — — — — — — — — —
 A pallid spiny softshell turtle (Apalone spinifera pallida) on the right end of the log with red-eared sliders (Trachemys scripta elegans) and river cooters (Pseudemys sp. or spp.).
 A crop of the first image, hence the poor quality. Shows a better view of the pallid spiny softshell turtle and some of the red-eared sliders; the turtle nearest the softshell might be a river cooter (Pseudemys sp.).
 A pallid spiny softshell turtle on the left, one obvious red-eared slider atop another turtle, and what could be either red-eared sliders or river cooters.
 A Texas river cooter (Pseudemys texana) on the right, an eastern river cooter (Pseudemys concinna) in the middle and a red-eared slider on the left. Also note the red-eared slider in the lower-left corner of the frame. (The water and turtles are covered with duckweed.)
 A baby red-eared slider resting atop an adult.
Note that differentiating the eastern river cooter from the Texas river cooter can be impossible without a clear view of the head pattern and shell pattern, and even then variability can lead to poor identifications. Red-eared sliders can be confused with either species if the red patches are not visible.
Some male red-eared sliders become melanistic as they grow older; this causes their skin to lose all colors except green and the green becomes darker as they age, hence they can be difficult to identify from a distance (see the first photo in this post for an example where the “red ears” have been reduced to negligible red spots and all the yellow has been lost).