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Mozambique Diary: The Lizard Quest

Harith Farooq holding a Rock monitor (Varanus albigularis). These enormous lizards are some of the largest reptilian predators of Gorongosa, surpassed only by fully grown rock pythons and crocodiles.

Harith Farooq holding a Rock monitor (Varanus albigularis). These enormous lizards are some of the largest reptilian predators of Gorongosa, surpassed only by fully grown rock pythons and crocodiles.

Sitting on the dusty floor of a makeshift laboratory tent Harith Farooq carefully folded a piece of fine, steel mesh into a foot-long cylinder, then weaved in a stretch of a thick wire along its edge. Finally, he carefully attached a neck of an empty water bottle to one of the ends and looked at the contraption in his hands with deep concentration. “Something is still missing”, you could almost hear him think, “but what? A battery? A fork? Some gasoline, perhaps?” His gaze shifted to a stack of paper mouse traps covered with thick, sticky glue, the kind that was meant to immobilize any animal unlucky enough to step onto it. “Bingo!” – Harith picked one up and squeezed it into the tubular apparatus. “The perfect leezard trap”, he announced proudly.

Swynnerton's amphisbaenian (Chrindia swynnertoni), a subterranean blind lizard, found only in Gorongosa and a small surrounding area.

Swynnerton’s amphisbaenian (Chrindia swynnertoni), a subterranean blind lizard, found only in Gorongosa and a small surrounding area.

For the last few days Harith, a Mozambican scientist from the University of Lúrio in Pemba and his colleague MO Roedel from Berlin, two herpetologists participating in a biodiversity survey of the Cheringoma Plateau in Gorongosa, had been trying to catch some of the many lizards found in the Nhagutua Gorge, the site of our first camp. Alas, the sneaky reptiles proved to be extremely difficult to catch by hand, which prompted Harith to come up with an alternative solution. As the survey progressed his traps kept growing larger and more complex, combining both natural materials (rocks, sticks, bark) and man-made objects – a plastic sheet, twine, wire and, of course, steadily increasing amounts of glue. The one thing that they all had in common was their total inability to capture even a single reptile.

Flap-necked chameleon (Chamaeleo dilepis) is common in the savanna woodlands of the Cheringoma Plateau

Flap-necked chameleons (Chamaeleo dilepis) are common in the savanna woodlands of the Cheringoma Plateau

The strangest part was that Harith was incredibly good at catching reptiles, or any other organisms, without the need for additional accessories. I had never seen anybody catching, with their bare hands, a giant centipede, a solifugid, or a deadly spitting cobra, but Harith caught them all, while carrying a casual conversation. In the end, during the Cheringoma survey he and MO collected 47 species of lizards and snakes, effectively quadrupling the number of reptiles known from Gorongosa National Park.

Within a three week period in Gorongosa our team of biologists was able to document the presence of all nine families of lizards that occur in southern Africa. Among them were some real gems, including an entirely blind, subterranean lizard, the Swynnerton’s amphisbaenian (Chrindia swynnertoni). These tiny reptiles, known only from a handful of specimens recorded around Gorongosa, spend their entire life underground, leading a lifestyle remarkably similar to that of earthworms, and feeding on termites and ant larvae.

Thunderbolt lizard (Nucras sp.), one of the fastest animals found in Gorongosa.

Thunderbolt lizard (Nucras sp.), one of the fastest animals found in Gorongosa.

On the opposite end of the lizard spectrum, two species of giant monitors (Varanus) turned out to be quite common on the Cheringoma Plateau. One day Harith walked into the camp carrying a live Rock monitor (V. albigularis) the size of a goat, which he had captured by throwing himself on top of the gargantuan animal, barely overpowering it with the help of two other people. The reptile’s snout was still covered with blood of the last victim, probably a bird or a small child, by the looks of it, and gazing into the monitor’s eyes made me realize how grateful I was that our species appeared long after the era of dinosaurs had passed. We released the beautiful creature after examining it for the presence of external parasites, which the lizard had none, proving its excellent health condition.

Plated lizard (Gherrosaurus major) was one of the most exciting finds of the survey.

Plated lizard (Gherrosaurus major) was one of the most exciting finds of the survey.

Almost every day our herpetological team, which also included a Mozambican student Francisco Domingos, recorded something new and exciting. Often it was a tiny brown frog that differed from all other frogs by the presence of a slightly enlarged corner of the left supraocular cuticular fold, which was enough to make our herpetologists prance and giggle with excitement like little girls. But at other times it was a vine snake that could kill you with a half a drop of its venom, or a spiny rock lizard that defends itself by squeezing into rock crevices and inflating its body like a balloon. The survey found charismatic chameleons, among them the famed pygmy chameleon of Mt. Gorongosa, unquestionably the cutest lizard in Mozambique, and blindingly fast lacertid lizards with flame orange tails, which looked like tiny thunderbolts zipping across the ground.

The survey officially ended yesterday, and Harith is on the way back to Pemba. Data collected by him and the rest of the herpetological team will be added to the ever growing Gorongosa biodiversity database, a powerful tool that helps manage the restoration efforts in the park. I was sorry to see the members of the team depart, but having witnessed Harith handle cobras and puff adders as if they were harmless puppies I was relieved to see him leave the park, still alive and well. All things considered, a gash in his finger, courtesy of a pouched rat, followed by a nip from a giant scorpion hardly count as injuries.

The male of the Gorongosa girdled lizard (Cordylus mossambicus) looks like an alligator wearing an orange T-shirt. These spectacular lizards are found only in a small area around Gorongosa and the neighboring Chimanimani Mountains of Zimbabwe, and are threatened by habitat loss and overcollecting for pet trade.

The male Gorongosa girdled lizard (Cordylus mossambicus) looks like an alligator wearing an orange T-shirt. These spectacular reptiles are found only in a small area around Gorongosa and the neighboring Chimanimani Mountains of Zimbabwe, and are threatened by habitat loss and overcollecting for pet trade.

Mozambique Diary: Is this tortoise broken?

An adult Hingeback tortoise (Kinixys belliana) from Gorongosa. What looks like a wound on its carapace is a flap of skin that allows the shell to close and protect the hind legs and tail.

An adult Hingeback tortoise (Kinixys belliana) from Gorongosa. What looks like a wound on its carapace is a flap of skin that allows the shell to close and protect the hind legs and tail.

Some time ago I was driving in Gorongosa when I noticed a large tortoise laying in the middle of the road, stuck upside down in the mud. The animal was alive but had what appeared to be a large wound in the posterior part of its cracked carapace. There were fresh tracks of a civet all around it in the mud, and I assumed that the civet found an injured tortoise (I didn’t think a civet could do it itself) and was hoping to eat it. I pulled the animal out of the muck and only then recognized what I was looking at – the tortoise was not injured at all, and what I took for a wound was a flap of skin that connected the front part of the shell with its movable back. Because it was not an ordinary tortoise, but a Hingeback tortoise (Kinixys), a member of a remarkable group of reptiles that are capable of closing shut the back of their shells to protect the hind legs and the tail. This, combined with the head tightly pulled into the front of the shell and blocked by its heavily armed front legs makes the hingeback tortoise virtually immune from attacks by smaller predators. Judging by the dense trail of civet tracks around the tortoise it seemed that the mammal had spent a lot of time in frustration, unsuccessfully trying to get to the soft parts of the reptile.

A juvenile Hingeback tortoise; its hinge is not yet developed.

A juvenile Hingeback tortoise; its hinge is not yet developed.

Although the movable carapace is a great way to protect the rear part of the body, the flap of skin that connects the two components of the carapace is a favorite location for another enemy of the tortoises to attack – the ticks. Every tortoise I found in Gorongosa carried several huge, heavily armed ticks (mostly of the genus Amblyomma), whose body shape and sculpturing was surprisingly similar to that of the tortoise. Carrying a bunch of blood-sucking ectoparasites is no fun, but the burden of being drained by them is probably particularly heavy on smaller, younger animals. A few days ago I found a tiny Hingeback tortoise, one whose hinge was not yet fully developed, and it carried on its leg one of the largest ticks I have ever seen. It was as if I had a parasite the size of a football permanently attached to my body. I removed the tick from the tortoise, put one of the animals into a vial of alcohol, and applied some antiseptic to the other and let him back on his merry way.

An enormous tick (Amblyomma sp.) on the tortoise's leg.

An enormous tick (Amblyomma sp.) on the tortoise’s leg.

Hingeback tortoises are quite common in Gorongosa, and I see them often as they cross the network of trails. But across Africa their numbers are declining as the result of habitat loss and collecting for the pet trade. Every year about 20,000 of these animals are exported to be sold in pet stores in the US and Europe, and Mozambique alone sends out about 3,000 of these animals every year (this is the official quota allowed by CITES, the actual number is undoubtedly higher). Luckily, recently the importation of most of Hingeback species was banned in the US. The reason – ticks. Some of the ticks carry a disease which, while not harmful to the reptiles, is often fatal to cattle – the Heartwater disease, caused by rickettsia Ehrlichia ruminantium. And so, the same parasite that makes the tortoises’ life miserable may in the end help them survive in the wild. I guess you never know who your true ally is.

Tortoise tick (Amblyomma sp.) actually looks like a tortoise, and its opisthosma is almost as hard as the reptile's shell.

Tortoise tick (Amblyomma sp.) actually looks like a tortoise, and its opisthosma is almost as hard as the reptile’s shell.

Insect-mimicking snakes?

A young ringed python (Bothrochilus boa) from Papua New Guinea. [Canon 1Ds MkII, Canon 180mm macro, 2 speedlights Canon 580EX]

A young ringed python (Bothrochilus boa) from Papua New Guinea. [Canon 1Ds MkII, Canon 180mm macro, 2 speedlights Canon 580EX]

New Guinea has quite a few venomous, really dangerous snakes. Death adders (Acanthophis), taipan (Oxyuranus scutellatus), or Papuan blacksnake (Pseudechis papuanus) are elapid snakes that have caused many human fatalities on the island. But the one thing that New Guinea does not have is coral snakes. The only venomous snake that looks like one is a hatchling of the small-eyed snake (Micropechis ikaheka), whose posterior half has alternating white and dark rings. It is therefore somewhat surprising that young ringed pythons (Bothrochilus boa), non-venomous and essentially harmless reptiles (unless you are a mouse, that is) advertise their presence with vivid, orange and black coloration. Their entire body has a shiny gloss to it, and it is impossible not to notice this animal as it glides through the leaf litter and low branches.

Aposemtic walking stick Megalocrania batesi from Papua New Guinea. [Canon 1Ds MkII, Canon 180mm macro, 2 speedlights Canon 580EX]

Aposemtic walking stick Megacrania nigrosulfurea from Papua New Guinea. [Canon 1Ds MkII, Canon 180mm macro, 2 speedlights Canon 580EX]

I puzzled about this seemingly counterintuitive behavior – why advertise yourself if you have nothing to back it up with, and local predators have never been exposed to venomous snakes of such a coloration? Is it still Batesian mimicry if there is no harmful model? Or perhaps the snake is colorful simply for the sake of being pretty (rather unlikely.) But then, one day while looking for katydids hiding among the leaves of Pandanus plants, I stumbled upon a giant walking stick, Megacrania nigrosulfurea. I was immediately struck by how similar its coloration was to that of a young ringed python that I had photographed a few days earlier: shiny black body, with bright orange legs, plus bright yellow spots. But why would a snake mimic a walking stick?

Burying beetle Nicrophorus heurni from Papua New Guinea. [Canon 1Ds MkII, Canon 100mm macro, 2 speedlights Canon 580EX]

Burying beetle Nicrophorus heurni from Papua New Guinea. [Canon 1Ds MkII, Canon 100mm macro, 2 speedlights Canon 580EX]

As it happens, many walking sticks, including the genus Megalocrania, are capable of synthesizing de novo noxious, repellant chemicals (other insects usually sequester such compounds from their food plants), which they then spray at the attackers with surprising accuracy. These compounds, mostly monoterpenes (e.g., iridodial, nepetalactone, anisomorphal), quinoline, and pyrazines, act as powerful deterrents to a wide range of predators, from ants to lizards to birds and rodents (opossums, however, seem to relish toxic walking sticks.) For the young python a walking stick that is avoided by all the same predators that like to munch on small snakes could be a pretty good model to imitate. And a few days later I also found in the same rainforest habitat a burying beetle (Nicrophorus heurni), which showed a similar combination of shiny black and orange coloration. Like the aposematically colored walking sticks, these insects are avoided by many predators thanks to their ability to spray the attacker with some of the stinkiest substances in nature, including phenol, indole and, most importantly, skatole (you can guess what the last one smells like.)

A single, casual observation obviously does not constitute a proof that ringed pythons mimic insects. But this would not be the first example of a vertebrate mimicking an aposematic insect: in southern Africa a small lizard Heliobolus lugubris mimics black and white Anthia ground beetles, known to have powerful chemical defenses. And if a caterpillar can mimic a snake, I don’t see why a snake could not mimic an insect.

Update: The name of the walking stick was misspelled and now has been corrected. Thanks to David Rentz for the tip.

Adult ringed pythons lack the bright, conspicuous coloration of the juveniles – it may be difficult to mimic a walking stick if you are over a meter long! [Canon 1D MkII, Canon 16-35mm, speedlight Canon 580EX]

Adult ringed pythons lack the bright, conspicuous coloration of the juveniles – it may be difficult to mimic a walking stick if you are over a meter long! [Canon 1D MkII, Canon 16-35mm, speedlight Canon 580EX]