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Sexing the Single Caiman

Monday, January 26, 2009

I suppose some people would look at this gatorbelly and think what a nice pair of boots it would make. That kind of lust for its beauty put the black caiman in a huge downward spiral from the 1950's to the '70's, and it's only just recovering from the slaughter. Black caimans, like so many creatures persecuted elsewhere (giant otters, for one), are still common on Guyana's beautiful Rupununi River. I am so thankful for Guyana, for the Rupununi, for huge reptiles that make a swirl in the water.

I looked at the caiman's tiled abdomen and said a prayer to all that is beautiful and perfect just as it is.

Ack. What are they doing?

Feeling for conclusive evidence of the giant caiman's sex, that's what. Think fetal sonograms: If you don't feel anything, it's a female. Male caimans, like all reptiles, and all aquatic creatures as I think about it, keep their wedding tackle inside until they need it.

I resolved not to shake Ashley Holland's hand when I thanked him for our excellent nocturnal adventure.

And it was a female, and her toes curled when they did the internal exam. Awww.

"They always do that," our leader commented. It felt disrespectful to laugh, so I covered it up with a little wheezy cough.

Because there are not too many places where you're going to be able to look close-up at a caiman's vent, here it is. I was awestruck. I had this flood of images running through my head, of cells dividing in the embryo, of God with a sewing machine, of somebody or some antic evolutionary force figuring out how to resize and then upholster those Formica scales smoothly over living muscle and make them fit, flexibly airtight, around a sphincter. Ye gods. Design, functionality, beauty and awe in a caiman's bunghole.

I am in Science Chimp heaven. Again. Geeking out, hands on a ten-foot, three-inch wild female black caiman. That's as big as she will probably get. Who knows how old she is? Whether she'll keep growing?

Males can get to 16.5 feet, and Wikipedia says "The largest reported black caiman, measuring 7.7 meters (25.2 ft) and weighing 1,310 kg (2,870 lb), was shot in Acre, Brazil in 1965 and, which if accurate, would count as the largest crocodilian recorded besides saltwater crocodiles."

Pause to let that sink in. Look around, eyes crossing. That's four feet longer than my living room. A twenty-five-foot-long black caiman? How would it even turn around in smaller rivers? How old must it have been?

and how I wish they'd marked and released it instead of shooting it. (It would only take about 20 men to hold it down, c'mon!) Here's the thing. Some reptiles are said not to stop growing over their lifetimes. Kind of like fish or haul up this leviathan, and the first thing you have to wonder is how old it must be.

Now, for the first time, right in front of my astonished eyes, researchers are getting growth and allometric and reproductive data on this species. To find out more about the study, initiated by herpetologist and conservationist Peter Taylor, please click the link. The study involves local Amerindians, who are learning first hand how to study and protect the species, and realizing the benefits from the ecotourism that follows having a healthy population of a spectacular reptile (not to mention a spectacular mustelid, felids and endless fabulous birds).

By a clipped scute on her tail, they knew she was a recapture. So they could compare how her measurements had changed since the last time they had her in the noose. This is how we learn, this is how we answer the questions I've posed and so many more.

It was kind of upsetting to see the wrassling necessary to subdue a study subject, but it was all good. For everyone but the caiman, I suppose. She was not enjoying herself anywhere near as much as I was.

Zick, a bundle of firing synapses barely contained by her Life is Good shirt. Photo by Erica Gies.

There there, old lady caiman. They're almost done with you now.

Measurements and sexing all done, it was time to truss the poor girl up like a Thanksgiving turkey so no bits would hit the ground when she was being hoisted up on the hanging scale.

Somewhere I wrote her weight, in the dark, maybe in my little notebook. I can't find it. I found some scribbles, but the weight isn't among them. Rats. At this point all us Marlon Perkins pikers were really, really ready to see the Jim Fowlers put her back into the water, free of all this manhandling.

The Guyanan assistant tied the most amazing knot to keep her jaws closed while the noose and the tape was removed. It could be loosened with just one tug, like the sewn seam on a 50-pound bag of bird seed. I watched him tie it, careful but lightning fast, and all the wonder I felt at the caiman's perfection leapt over to those beautiful hands. Homo sapiens is one boffo primate.

They carried her to the water's edge--grunnnnnt!-- and pulled on the magic knot with a long cord.

One tug, and she was free, and nobody had to lose a hand untying her jaws. Pretty dang slick.

The whole time she was lying trussed up she was sighing, a deep, watery rumble from her very guts, and the sound moved me, as the sighs of a beached whale would. It was good to see her great jaws come open, and she said Ahhhhh again and then she was gone, just a huge muscular lash on the water's surface.

And silence, and the sound of my own breathing.


Wow! Amazing. I can't think of anything to say, but Wow!

a "REcapture" -- how unlucky is that! -- she must be thinkin' to herself, "dagnabbit, not those %$*#@*!! clowns with that $#*@&! rope again. Sheeesh!"
-- seriously, I wonder how much memory for such experiences they carry around in their reptilian brain.

Fantastic - I saw their eye shine once on the Rio Caura - beautiful to see the close-up images in your account. Thanks for sharing this.

"At this point all us Marlon Perkins pikers were really, really ready to see the Jim Fowlers put her back into the water".

Thank goodness for the Jim Fowlers of the world who make it look easy and thank goodness for the Julie Zickefooses of the world who can turn a short post about caimans into a profound spiritual moment. And we too are left with silence and the sound of our own breathing.

I just hope Ashley keeps his finger nails cut short.

It's so much to comprehend...mind boggling, soulful, personal.

Nearing the end of this post, on the edge of my seat, I was relieved to see her release! Thank goodness for that.

Yes. Wow. Wow. Wow.

I laughed, held my breath and got misty in the few minutes it took to read this moving post. Thanks for the wonderful ride.

Mary, I am going to be bad now.

Sexing with release: good. Toe-curling good.

Back to our regularly scheduled reverence.

Thank you, Kathleen, Timmers, Bargeview, Island Rider.

Cyberthrush: I'd bet they remember and connect a whole lot more than we'd expect. Big things that live many decades tend to be pretty bright.

"Wow" about the cloaca scales, the shear size these guys reach, the series of knots that allowed her release to go so smoothly, that people care enough to watch over these at-risk creatures. An incredible experience through your eyes, words and, yes, breath.

Away from my computer till tonight, I was on fire to read the caiman story. The "toe-curling" part made me giggle just a bit.

one question: If she was a recapture, didn't they know her gender from before? Why would they sex her again?

Glad to see you got to touch at least one creature in Guyana without being bitten.

Nice series, Julie!


I wondered the same thing, Kathi, and then realized that, being soaked and in and out of the water and wrasslin' and all, they didn't exactly have their data in front of them. They could tell she was a recapture by the clipped tail scute, but they didn't have a way to look her up to see who she was. They recapture only around 10% of the caimans they mark, so she was a very valuable animal (scientifically speaking). They hadn't seen her for a year or so and can't have all the data in their heads. At least that was my take on it. I was trying to get pictures but stay out of their hair so did not ask too many questions.

Way cool. WAY. COOL.

And I find it terribly cute that she curled her toes. Interesting, telling, and cute.

Yes, that would leave me listening to my own breathing as well. Living dinosaurs who still walk the planet. That would be a spiritual experience indeed. Thank you.

Such a wonderful and rare experience for you, and us through your telling. It must, now, seem like a dream.

What a night... toe curling and release.

Great writing, thoughtful and caring.

This is perhaps your finest post ever. You should really think about becoming a nature writer.

I'd like to add that I am glad I know my gender without anyone having to check it caiman-style.

What an amazing experience. I imagine it's not just any ecotourist who visits who gets to do that.

Do they clip the scute in a particular pattern to tell one from another? Or does each caiman get a different scute clipped? I was actually looking at the underside of her tail and was reminded of humpback flukes or your previously-mentioned giant otters, who sport a different pattern of markings on each individual. Can the same identification trick be used on caimans, or do they recapture them so infrequently for that to be more effort to record than it's worth?

In regards to Kathi's comment, I've spent several years as a bird bander, which is essentially the same sort of mark-and-release that they're practicing with the caimans. We go through and take every single measurement again on a recaptured bird (unless it was caught within a few hours ago, in which case we just let the poor confused thing go), even though we have all of that season's data in the binder with us, since recording even the stuff that doesn't change - age (if the same season) and sex - serves as a double-check against previous banders' assessments, and also ensures that the data was written down correctly. You'd be surprised at how easily a piece of data can be mis-transcribed in the flurry of activity.

Thanks for checking in, BOTB. You would be a notable exception to my aquatic beast rule. Come home, will ya??

Seabrooke, as they've marked 400 caimans thus far in the project, and recapture only about 10% in this study area, I would imagine that working out subtle differences in belly scute pattern could be a path to madness. I don't know their system for scute-clipping but it's not particularly subtle--there was a whole top-zag of her tail clipped off.

Since they're trying to get allometric data, all the measurements need to be taken afresh each time to give some data points that will help tell them how the creatures grow. And as you point out, you might as well sex them while you're at it, because maybe they got it wrong the first time. Yep, still a female!

"Ahhhh! I could bitecha, I could bitecha, but I won't. But I could. Just so's you know."

Yet another alien re-abductee goes free. Again.

I often wonder if the Box Turtles I pick up and put across the road (that they may be on, or fixing to cross) think, "Oh, for the love o'god, not another one of THEM!" Lucky for them, I've only been guilty of visual, not tactile, sexing. (Which pretty much sums up my social life of late, too.)

Catbird, you are soooo fulla beans.

So THAT's what the aliens are doing when they...never mind.

Hey Julie,
They told us she weighed about 200 pounds. Thanks for finding the link to the study!

Oh, dopey me - of course they wouldn't have all their records right in front of them. Even if they did, they wouldn't want to take the time, with the her all trussed up, to go look her up. It is easier and faster (not to mention more scientific) to recheck. Plus, more enjoyable for the caiman!

Besides, maybe the previous person who sexed the caiman GOT IT WRONG. Shouldn't rely on somebody else, but always CHECK FOR YOURSELF, as I recently learned!


and if sexing these critters is so involved how does the male caiman know when he's in the presence of a female caiman (or is it just the way she bats her eyelids at him)?

Whoa--such a wondrous encounter.
'Nuff said.

A belated entry: I agree with BOTB, Julie.

In the process of getting caught up, please forgive my tardy comment here. What an amazing post. Aside from the incredible facts presented (WOW!), the pace and style of writing was.... well, delightful! From the excitement of touching the wild beast, to the animal's breath, to the final tranquility of the croc's release. So lovely

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