Above: Female yellow-bellied slider looks to see if it’s safe to come ashore to lay eggs.
It was May. Aquatic turtles of various species were up and walking along the paths and woods of the Museum’s outdoor exhibits, in fact, they could be seen throughout the entire Museum grounds. They were looking for suitable nest sites. When looking for nest sites turtles most often choose sites alongside roads, paths or mulched planting beds, at least that’s where they’re most often observed laying eggs here at the Museum.
Three such nests were observed this past spring by either myself or Ranger Kristin. Two were Yellow-bellied Sliders and one, an Eastern Painted Turtle. One turtle was actually observed in the act of laying her eggs.
The egg-laying turtle, observed by Kristin, is well known to many of us at the Museum, a large chunk of her carapace is damaged making for easy identification wherever she wanders. She was observed dropping her eggs as Kristin sat nearby watching her. Her preference was a mulched area between two pine trees next to the Meadow in Catch the Wind. She deposited her eggs on June 7, a few weeks after the others.
The two nests that I observed were in the process of being covered up by the turtles as I came upon them. The painted turtle was first spotted by Animal Keeper Mikey as he made his rounds on the morning of May 20 near the Red Wolf Exhibit. The yellow-bellied was in Catch the Wind next to the Sailboat Pond.
Most references state that its about a 72 day, or 2.5 month, incubation period for eggs of both species, 80 days on the outside. It’s also reported that the young may overwinter in the nest. I’ve seen many examples of that here at the Museum. A young yellow-bellied or painted turtle making its way to the Wetlands in March or April is surely a turtle that overwintered in the nest, whether as an egg or hatchling (a question for another time). The ones that I find in spring still have an “egg tooth” which suggests that they had recently hatched.
It’s now September and I’m wondering what happened to the eggs in the nests. It’s well over the 72 days, 2.5 months, or even the outside number of 80 days for the eggs to hatch. So on September 3, we decide to dig up the nests and see what lies within.
Will we find shriveled-up dessicated eggs, empty nests (the turtles hatched but left no obserevable indication on the surface of their departure), perfectly intact eggs, or eggs and hatchlings that have been ravaged by ants? There’s no other way to find out but to dig!
When the adult turtles locate a suitable site to dig their nest they urinate to soften the dirt for easier digging. In our area that dirt is hard, clay-based soil. Anyone in this area who has set fence posts can attest to the soil’s unyeilding nature. This fact also makes for a very firm, almost inpenetrable, covering for the nest when it dries.
Although there were five healthy young turtles in the nest there were also a couple that had started to hatch and for some reason didn’t survive (perhaps ants), one egg was not viable, and one was partially hatched.
Even though some of the turtles didn’t survive, it was turning out to be a very rewarding day.
It was now off to the painted turtle nest in Explore the Wild. Could there be more turtles in that nest? Feeling good about finding turtles in the yellow-bellied’s nest we dove in with optimism.
Once again, careful digging so as not to harm any potential inhabitants.
There were no obvious clues as to where the actual nest was, remember, the yellow-bellied nest was equidistant between two trees, fairly easy to find. With this nest we were going from memory of three months time.
The painted turtles were smaller than even the yellow-bellied turtles.
We only found three young painted turtles with no evidence that there had been any others in the nest. Apparently the adult had only deposited three eggs in this nest.
Why had it taken so long for these turtles to hatch? Why hadn’t they dug themselves out of the nest when they did hatch? Some of the nestlings, at least in the yellow-bellied nest, had hatched several days prior to being dug up, perhaps much earlier. It seems that the answer to those two questions may have to do with the hard clay that makes up our soil here in the Triassic Basin in which we live, and with the lack of rain this summer.
As already mentioned, when turtles dig out their nests in spring they urinate on the site to soften the dirt for digging (turtles must have very large bladders, each nest that I’ve come across has been saturated with liquid). When the clay dries after egg laying is complete it forms a hard shell around the eggs. This “hard shell” was very evident when digging up the nests above.
Turtle eggs need warmth and moisture to properly incubate. There was plenty of warmth during summer, but a definite lack of moisture. At least one of the eggs simply didn’t incubate properly or was not fertile, while the young that did hatch couldn’t dig through the hardened clay. Remember, dry clay equals hard clay. As it happened, it rained heavily a few weeks after we dug up the nests, although that may have been too late for our little turtles.
The third nest, the one next to the Sailboat Pond, sits undisturbed. I’m going to keep an eye on that nest to see if there are young that emerge from the site next spring. By the way, the Sailboat Pond nest was excavated by a yellow-bellied on May 16, several days to a week earlier than the others.
Thanks to Animal Keepers Kent and Mikey for their encouragement, patience, and knowledge, both were very helpful in answering many questions. A special thanks to Mikey for coming out to the nest site in Catch the Wind when called upon at the last minute to answer even more questions and provide assistance when we actually found turtles alive in “Chip’s” nest.