He picked up an indigo snake

To catch a mud turtle you should grab both sides of the shell towards the back, or the long neck will swivel around and the turtle will bite you. In the lower pool at McKinney Falls State Park was a Texas river cooter turtle, which we could recognize by the curving yellow on its face. Dave called it Pseudemys texana, and caught it.

A green kingfisher flew calling up the creek. A snowy egret ran around stirring up crawfish as if it were one of those crazy reddish egrets, dancing for food. A green heron sat motionless on a limb over the water.

A water snake swam towards us, and Dave dropped the nets he was carrying to lunge in after it. He showed us how it hunched back its head to make it seem triangular, but this harmless Nerodia erythrogaster transversa could not poison us, though it could bite. It unloaded its lunch in attempts to get away from us. This one was a female and we knew this because its tail narrowed so much past its anus. A side view of its face showed a smiley face, though this snake had nothing to smile about right now, though we let this and every animal we caught go right where we found them.

It was 19 May 2005, and I was beginning a magic two weeks as a guest in David Hall’s vertebrate natural history field course at University of Texas at Austin. It was a special intensive version of the course taught entirely in May. We began with several days in the laboratory, listening to lectures, and handling pickled snakes and fish, and the like, and stuffed birds and mammals. I tried to learn everything I could, but I did not take the tests. I kept wondering if these students knew how lucky they were to have this opportunity. I was delighted to be invited to join a course taught by my own former Rice University undergraduate.

There were clear spots in the sun-speckled water, guarded and tended by male sunfish in the family Centrarchidae. This was one of the first of many natural details others might notice, and walk right past, thinking they were a feature of the currents, or not curious at all. But we saw them because Dave pointed them out and taught us to look carefully. Apparently the cleared spots were better for eggs, and these daddies would take care of any female’s eggs if they could simply provide the sperm. Guarding these territories must be a costly business because some males skipped it, preferring instead to sneak in sperm while the chosen pair were mating. Sometimes these sneaker males look like females.

These are common stories for fish. You see, they have external fertilization, at least most species do. As the female lays the eggs, the male bathes them in sperm, fertilizing them. Because the male has a territory to attract females, and mates with her there, it is not too much more costly to simply stick around and care for the eggs, being sure they are safe, fanning them to bring on the oxygen, and munching on a few if hunger strikes. There’s lots more to learn about fish mating behavior, but we moved on, exploring up the cool May stream.

We dragged a seine through the stream to see what else was there. It is a net held across the stream by two people, and has weights on the bottom and floats on the top. We caught bluegills, minnows, and a buffalo fish, then put them in the fish viewer, a plexiglass V with water to see the fish.

We also saw a northern cricket frog, Acris crepitans crepitans, and a ground skink, Scincella lateralis.

This was our first outing and we went back to class. The camping would begin in a couple of days, and start at Brazos Bend State Park, back near Houston. We learned so much of the natural history, behavior, morphology, and general habits of Texas wildlife on those hot May days. I can’t imagine another experience as intense as this one, and will periodically share other days from the course as we wound down to South Texas, and then west.

Maybe we should retrace our steps through Texas before we leave. I know Alan Templeton will show us the wonders of Missouri and I’m looking forward to it.


Dave Hall from an earlier field trip to Kickapoo Canyon State Park holding an Indigo snake

.sunfish territories.JPG

Those light spots are sunfish territories.


About Joan E. Strassmann

Evolutionary biologist, studies social behavior in insects & microbes, interested in education, travel, birds, tropics, nature, food; biology professor at Washington University in St. Louis
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