• Dr. April Reside

Caiman Census and a Parasitic Maggot Named ScoMo (note: graphic)

We borrowed some kayaks to head out on the Cocha to do a caiman census. In the fading light we watched masked crimson tanagers flitting about the trees, and a pair of snail kites on the nest. We relished an opportunity to bird watch without hurting our necks! We saw the little water birds skulking among the cane grass: rufous-sided crake, blackish rail and sungrebes. On dusk we watched the magnificent agami heron hiding in the thick riparian vegetation. Just as it was getting too dark to see, we paddled out into the middle of the lake, tucked our kayaks together side by side and had a little picnic dinner in the dark. I wrapped myself up in multiple layers of clothing to protect against the mosquitoes until I resembled a badly dressed nun, and then it was time for censusing.

Caiman crocodilus aren't as scary as our salties

The caiman in the Cocha are all black caiman (Melanosuchus niger), except for those in the little side creeks which are Caiman crocodilus. The caiman’s bright, distinctive eye shine are very easy to detect from one side of the Cocha to the other. Except, as it turns out, when the mayflies (Order Ephemeroptera) descend in their thousands. It became a routine of: turn headlight on, see for 30 seconds, turn headlight off, wait for mayflies to disperse for 2 minutes, repeat. We swallowed so many arthropods that I wonder why we bothered to have dinner. Bats were zooming across the Cocha in the hundreds, it was amazing to watch so many cross the beam of our lights simultaneously. We felt cheated when we saw some catching fish. “The bugs!” we cried. “Eat the bugs, not the fish!” At one point I saw Beloved so completely enclosed in a cloud of insects that I couldn’t stop laughing. Until I swallowed a mouthful of my own.

View of the Cocha (Oxbow lake) at Cocha Cashu

Fish were jumping in the beam of our lights too, Beloved reported many landing in his kayak, one even smacked him in the neck. I felt a bit left out. Where are my fish? But when a big flapping jumping fish landed in my lap it was a matter of ‘beware of what you wish for’. It wasn’t so easy to scoop up the slippery slimy bugger and evict it as it flapped about the boat. Over by the edge of the Cocha I saw a eye shine in vegetation above the water. “SNAKE!” I called out when I found a small boa in a branch hanging over the water. It was a juvenile Corallus hortulanus, with beautiful pink and purple hues. Around the corner we found substantial eyeshine up on the bank, so came ashore to investigate. I beached the canoe in the mud and scrambled up the bank a bit. Beloved tried a more elegant approach by climbing out on a log. “Yikes it’s a big muthapucka of a caiman!” I announced, backing away. “It’s a female on a nest!” Beloved reported, “Let’s leave.”

Sphaenorhynchus dorisae

Further on a swampy shallow patch full of emergent grass was a party of hopeful frogs calling away. It was difficult to hear each other over the racket. We found a couple of species we hadn’t seen yet: a beautiful green Sphaenorhynchus dorisae and adorable yellow-and-spotted Dendropsophus triangulatum, even sharing the same emergent grass blade. Also hopeful, but for a meal of froggy goodness, was the aquatic snake Helicops angulatus.

The aquatic Colubrid Helicops angulatus. Looks pretty friendly eh? Not if you're a frog I imagine

We found the boat billed heron hiding on the edge of the Cocha, difficult to see because of its nocturnal habits. After a few hours, I was thoroughly soggy, exsanguinated, itchy and full of mayflies; so was happy to return to shore to debug.

Dendropsophus triangulatum

Meanwhile, Beloved had mentioned a bite just under his right shoulder blade that had been bothering him for two or three weeks. He thought it might be a botfly larva. To my untrained eyes, it just looked like any of the other dozens of bites we’re both covered in – we have been regularly ex-sanguinated by mosquitoes, midges and other biting flies while out every night searching the swampy areas for frogs (Geez I’d be happy to donate some blood if they’d just ask nicely!). So when beloved mentioned this bite again a further week later, I thought it was time for some expert advice. “What does everyone reckon about this? Is it a botfly?” I asked the general congregation one hot afternoon. The crowd unanimously diagnosed botfly, and there were even claims that someone could see it ‘breathing’.

ScoMo the botfly larva. It was fairly inoffensive at the start

So naturally the next order of business was to give it a name. We Australians quickly agreed that the other parasitic maggot of the month has been ‘affectionately’ nicknamed “ScoMo” so Eric christened his namesake. The second discussion was of what PETA would want us to do. What is the protocol for the ethical treatment of a carnivorous botfly larva? Beloved elected to incubate ScoMo for a while to see what would happen. After further consideration, Beloved thought it would be good to put it to the vote. He enlisted help to get a nice macro shot of ScoMo, and entered the photo in the EBCC’s weekly photo challenge with the caption: “Cocha Cashu decides: does the botfly stay or go?”. ScoMo won, 16-4. I was worth 2 of the against votes, but was resoundingly voted down.


Tracking ScoMo's size with the outline of my camera battery. He's been mistreated a bit, too much scratching.

Like Brexit, it is important to consider the realities of a popular vote. A few days later, ScoMo was getting twitchy, particularly during the night. Ettore explained that botfly larva is like a baby, requiring feeding regularly and through the night, and that we should give ScoMo the appropriate love and care so he can incubate into a beautiful botfly grub. Hmmmm personally I think ScoMo may have to go soon.

Ok ScoMo has got to go!

Three days later, ol’ ScoMo was becoming an itchy, pussy, bloody mess. Beloved declared: “Hey ho, ho ho, ScoMo has got to go!” So after surveying the options presented to us: killing it with a topical application of a tobacco paste; or asphyxiating it with masking tape, nail polish or a slab of meat; Beloved decided on the Vaseline method. With a crowd of supportive onlookers, I smothered a thick paste of Vaseline over ScoMo. Given the heat, we were worried that the Vaseline would just sweat straight off, so we added a patch of tape over the top of the lot. A few hours later, we peeled back the tape to discover that the sweat and puss had displaced the Vaseline, and ScoMo was fighting back. We could even see the little breathing tube poking out, pulsing. We declared it a failed attempt and went off to catch some bats instead.

Enough tape, do you reckon?

The following day we opted for the asphyxiation-by-tape approach. Gaffa tape was applied, and Beloved told to wait 24 hours. Botfly larvae have backwards pointing spines, so when alive they are adept at keeping themselves buried. So they have to be dead or almost dead before they can be extracted. The next morning we unveiled ScoMo by peeling away the tape. We couldn’t detect any pulsing so decided it was time for ScoMo to be extracted. With onlookers I gave ScoMo a squeeze. Out popped a small white tube – the breathing tube was out! Unfortunately the tube broke off while we were tugging it out. So we had to squeeze out the rest of ScoMo. We were surprised at how small ScoMo turned out to be – not much bigger than a grain of rice. Ettore returned from his bird counts to discover ScoMo gone. “My life has no meaning right now,” he cried. All that drama for such a small critter! Glad it’s out.

So much drama for such a small critter. Most of ScoMo is a bloody mess here but the white breathing tube is separate, below.

🐸

This blog post has been kindly provided with permission by Dr. April Reside, Postdoctoral Research Fellow at the Centre for Biodiversity and Conservation Science at the University of Queensland. Please check out her blog Conservation on the Fly for more fascinating entries:

https://aprilreside.wixsite.com/conservation


Please follow Dr. Reside on Twitter https://twitter.com/april_reside

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