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Excerpts from Jim Conrad's
Naturalist Newsletter
from the July 23, 2017 Newsletter issued from Rancho Regenesis in the woods ±4kms west of Ek Balam Ruins; elevation ~40m (~130 ft), N20.876°, W88.170°; north-central Yucatán, MÉXICO
RINGED SNAIL-EATER
Despite not liking to look at roadkill, certain animals, especially nocturnal ones, are very seldom seen by average people other than dead along the road. Therefore, last Sunday on my banana-buying trip to Temozón, I just had to stop for a better look at the little snake shown above
At first I thought we'd already seen this species, the Short-faced Snail-Eater, shown -- also as roadkill -- on its page at www.backyardnature.net/yucatan/snaileat.htm
However, the yellowish bands on that black snake are relatively much wider than those on our Temozón snake. Sometimes regional variation accounts for such differences within a single species, so I almost didn't even photograph this new one. However, I did, even getting a close-up showing diagnostic scale patterns on the poor snake's head, shown below:
And the "undivided anal plate," another important field mark -- the round-topped one in the picture's center -- shown below:
This turned out to be a new species for us, the Ringed Snail-eater, SIBON SARTORII, distributed from central Mexico south to Nicaragua. Several species of snail-eater snakes occur in the American tropics. Mostly they're nocturnal, as you might expect of something that preys on snails, since snails like the night's moisture. Besides snails, snail-eaters feed on slugs, but little or possibly nothing else.
Most snail-eater are highly arboreal, but our Ringed species usually sticks to the ground. It's regarded as common in forested and disturbed habitats, just like what's found along the road to Temozón.
issued on August 22, 2019 from near Tepakán, north-central Yucatán state; elevation ~9m (~30 ft), N21.053°, W89.052°; MÉXICO
RINGED SNAIL-EATER ON A VERTICAL STONE WALL
In mid morning I walked into the hut and found a two-ft-long Ringed Snail-eater moving along the vertical stone wall, shown below.
The yellow noose is the loose end of a cord holding up my mosquito net. The vertical wall has an irregular surface but, still, I was amazed to see how easily the snake slithered along it.
issued on July 24, 2019 from near Tepakán, north-central Yucatán state; elevation ~9m (~30 ft), N21.053°, W89.052°; MÉXICO
VARIABLE CORAL SNAKE EATS RINGED SNAIL-EATER
Yesterday, standing where the outside kitchen's concrete floor makes a corner with the stone hut, as I removed from my backpack my weekly supply of bottled water purchased in Tepakán, movement at my feet caught my eye. Right below me I saw what's shown below:
Next to a stacked bunch of aluminum bars being used to improve the hut, that's a Variable Coral Snake, MICRURUS DIASTEMA, eating a Ringed Snail-eater, SIBON SARTORII, the latter not a lot smaller than the former. Below, up closer, you can see the mechanics of the situation:
The coral snake has unhinged his jaws but, still, one wonders how the coral snake will be able to get all that snail-eater inside him. A closer view appears below:
The drama had begun at 8:30AM. I suspect that the coral had just attacked the snail-eater as I walked into the area, for during my first close look I could still see an eye of the snail-eater in the coral's mouth-corner, and the snail-eater was squirming, the coral's venom not yet having done its work. For the first half hour, the swallowing process was very slow, hardly advancing at all. The coral would thrust his head forward, but usually no change could be seen in the snail-eater's disappearance.
After each lunge, which came at about two-minute intervals, the coral would pull on the snail-eater, who had his tail wrapped around an aluminum bar. Possibly the pulling caused the coral's fangs to sink deeper into the snail-eater's flesh. Also, corals are mostly nocturnal, the morning's light was growing more intense, and I was standing there taking pictures, so surely the Coral wanted to drag the victim into the less exposed situation among the bars or below the table. Also, with each lunge the coral's head turned a bit in a clockwise direction, so that during the entire lunging process the coral's head spiraled so that sometimes it was upside-down. In that half hour, about two head rotations were made, though most of the body didn't rotate.
After about half an hour of this lunging and pulling, with hardly any progress made in the swallowing process, the snail-eater stopped squirming, though his tail remained wrapped around the aluminum bar. Now the swallowing process sped up dramatically and the coral's head no longer turned. However, when maybe half of the snail-eater had been swallowed, a certain problem began developing for the coral, as shown below:
Though the snail-eater no longer resists, the rear part of its body has become wedged beneath the aluminum bar it earlier had been wrapped around. Below, you can see where the swallowing stalled and made no progress for about 45 minutes.
From time to time during this stalemate, despite the coral's clear aversion to exposing himself, several times he brought his body from behind the stacked bars and felt around with it, trying to find something to wrap its own tail around, and gain better purchase for pulling on the snail-eater. However, there was only the flat concrete floor, and decaying leaves piled by the wind here and there. Gradually the coral's body gathered leaves around its body, though I'm unsure whether it was incidental, or a conscious effort to hide himself. Below, you can see the resulting situation, the coral's body mostly hidden by leaves, while its own tail is wrapped around a bar:
At 11AM, after 2½ hours of watching, seeing that the coral was making no more progress swallowing the snail-eater, I decided to lift the bar so that the feeding could end. A good biologist would have wanted to see it end without human intervention, but I'm not trying to be a scientist. I just want to pay attention to things and I don't worry about being empathetic with coral snakes. When the post was lifted, about a finger-length of the snail-eater's slender tail remained to be swallowed. By the time I could get the camera into position, only the black, red-tipped tip of the tail remained, sticking like a toothpick from the corner of the coral's mouth, as shown below:
Notice that the end of the coral snake's tail ceases having yelow bands framing the red bands. The end is just black and red, exactly like the snail-eater's. I wish I knew if the coral's tail had been used to attract the snail-eater to within striking range...
issued on February 17, 2020 from near Tepakán, north-central Yucatán state; elevation ~9m (~30 ft), N21.053°, W89.052°; MÉXICO
SHED SNAKE "SKIN"
On the forest floor a fragile, silvery snake "skin" turned up, the head-end part shown below.
For identification purposes, nothing surpasses the importance of the number, shape, arrangement, and relative sizes of scales on the head. In the above picture we see such details as the thin covering of the eye that was shed with the "skin." Also a nose hole. The paler part at the image's bottom is the snake's undersurface, with its own scale patterns.
The scale pattern seen here leads me to what so far has been the most frequently encountered snake species at the rancho, the Ringed Snail-eater.