Wednesday, November 18, 2009

A Shell Game

Lars was in the Stow Town Forest between Elizabeth Brook and the Assabet River. I came on an apparently raided clutch of eggs that a carnivore dug out of a sandy embankment of glacial till (SW facing). I counted about thirty eggs dug out of the hole. The hole was 12 x 12 in, and claw marks were visible along the back wall of the hole. Each egg (if whole) would be relatively oval and just less than 1 inch long. They are the consistency of something between a soft ping pong ball and very thin birch bark.

I was in relatively dry surroundings, about 100 yards from the brook. I wonder if it is more likely turtle than snake. Snapper? The site looked more raided than hatched, especially with the manner by which it was dug out.

I would love to hear your thoughts. Lars


  1. I admit to knowing next to nothing (okay, nothing at all) about amphibians and reptiles, but a quick google search makes snapping turtle seem right, as I'm sure you discovered. I learned some very interesting things about their reproductive behavior, so thanks for posting.

    I don't know where snakes lay their eggs but I don't think they can dig holes (no legs) so if they lay them in a hole, it has to be an already existing one.

    As for digging predators, 'coon, skunk, fox, mink, coyote, and so on....My guess would be that the larger critters eat the entire egg, shell and all, so one of the smaller fellows would be more likely in this case....

    Exciting find. Thanks for posting

  2. Having had one experience with turtle eggs many years ago, I am definitely inclined to go with Janet on this one. (Especially considering the size.) One big question in my mind, though ... why would any eggs be around this late in the season?

  3. Ah, well, that was one of the interesting things I came across in my little google search. They have a very long egg laying season, from something like early summer through November (though lay only once in that time frame, I think). The eggs hatch 2-6 months later, depending on weather and time of year laid. Which means that sometimes they overwinter as eggs. What I wondered was, what exactly triggers laying, and then what triggers embryonic development and hatching. I didn't get that far in my reading, but I'm sure there is a very interesting story there. Compared to the narrow window of opportunity for breeding that many other animals have, the snapping turtle's breeding biology seems incredibly flexible. A great adaptation to.....something, I'm sure.

    Oh, and I recall something about the female's ability to store sperm for a very long time after mating, until she is "ready" to fertilize and lay eggs. What determines "readiness", though, I know not.

  4. Pretty fascinating information, Janet. Add that to the long list of things I never would have imagined. This may explain Leigh's recent sighting of a large snapper on the move down at the reservoir (the one in the woods between the golf course & Forbush). Given the recent spells of warm weather, it's not out of the question that it was a female on an egg-laying expedition.