For today’s photo and explanation of traces of the Georgia barrier islands that beguile, I’ll turn to one of the more charismatic and well-known of tracemakers, and what are among the largest traces of any animals on the Georgia coast. These would be alligators (Alligator mississippiensis) and alligator dens, respectively.
See those two big holes just above the shoreline of this freshwater pond? Those are alligator dens, large burrows that benefit them in many ways. And just to prove this point, these two dens have a pair of alligators hanging out at their entrances. Both alligators are only about 1 meter (3.3 feet) long, though, which means they’re way too small to have been the alligators that made these dens. So what’s going on here? (Photograph by Anthony Martin, taken on Sapelo Island, Georgia.)
I’ve written several times before about alligator dens on the Georgia barrier islands, and these are a subject of on-going research for me and several colleagues. So I won’t go on about them here, and instead will just focus on what this specific photo of these dens and alligators tells us.
The picture was taken in March, 2011, at the start of spring on the Georgia coast. Hence the alligators might have been just then coming out of dens after overwintering in them. However, notice the mismatch in sizes of the alligators compared to the den entrances. The dens are much too large for their denizens, implying that these are not their original makers, but instead are secondary occupiers, reusing these dens. I was also surprised to see five alligators – all about the same size – sharing dens. Yeah, I know, the title of this post says “four ‘gators denning,’ but you’re only seeing four of them in the photo; the one on the right had at least three I saw that day.
A little bit of background might help with understanding what was happening there and then. I’ve been revisiting this freshwater pond on Sapelo Island for nearly 15 years, and can confirm that these are the same dens. Sometimes I’ll see evidence of alligators actively using them, as in, I see alligators lying at their entrances, and alligators that retreat into these dens if they get too shy from all of the enthusiastic ichnologically inspired love I’m sending their way.
Sometimes those alligators have been large, full-sized adults with body widths only slightly smaller than den widths. Other times the alligators will be most modestly sized, like these. Regardless, this shows that once a den is made, it can be used by many alligators of varying sizes, over more than a decade, and possibly over generations.
Something else interesting about this photo? All four of the visible alligators – and the one you don’t see that’s in the den to the right – were about the same length. Along with their congregating in the same location, this is a hint that they might have been siblings, having hatched from the same egg clutch and grown up together in this pond. Even better, their mother might have raised and protected them there by using one or both of these dens. This means that alligator dens might be passed down in families and occasionally shared out of necessity by family members. You know, just like us. Amazed? If so, thank ichnology for inducing that sense of wonder.
Into the Dragon’s Lair: Alligator Burrows as Traces. Written by me, published on this blog March 15, 2012.
Deconstructing an Ichnology Abstract, with Alligators. Written by me, published on this blog October 19, 2012.
What a Big Momma Alligator in Her Burrow Tells Us about Dinosaurs. Written by me, published on the BBC’s Walking With Dinosaurs site November 20, 2013.
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