Archive | April 2013

Mozambique Diary: Golden bats

A colony of Lander's horseshoe bats (Rhinolophus landeri) – notice the orange hairs in the armpits of the flying male.

A colony of Lander’s horseshoe bats (Rhinolophus landeri) – notice the orange hairs in the armpits of the flying male.

Tomorrow marks the first official day of the Gorongosa Biodiversity Survey on the Cheringoma Plateau. All participating scientists are arriving, and the following morning we will depart for the first, northernmost site. But even before we get to those remote and unexplored areas, some of us have been already collecting interesting data.

Earlier today Jen Guyton, the expedition’s bat and rodent specialist, discovered a large colony of bats in an old, abandoned concrete water tank on the outskirts of the Chitengo Camp. It was too good of an opportunity to learn something new about bats of Gorongosa to pass by. Armed with a large butterfly net Jen had descended deep into the dark and rather odoriferous structure, and soon emerged triumphant with half a dozen bats fluttering in the net. She immediately identified them as Horseshoe bats (Rhinolophus), members of the family Rhinolophidae.

Two color morphs of Lander's horseshoe bats (Rhinolophus landeri) found in Gorongosa.

Two color morphs of Lander’s horseshoe bats (Rhinolophus landeri) found in Gorongosa.

These mammals get their common name from the characteristic, horseshoe-shaped noseleaf, an intricate structure on their faces that is the source of their echolocation signals. The ultrasonic signals of horseshoe bats are unusual in their relatively long duration and constant frequency, as opposed to more typical, short signals of shifting frequency found in most other insect-feeding bats.
Our bats turned out to be Lander’s horseshoe bats (Rhinolophus landeri), and the Chitengo colony had two color morphs of this species, one of which had a beautiful golden fur, which reminded me of that of the Amazonian Lion Tamarin. Lander’s horseshoes appear to feed mostly on moths, and can be identified among related species of the genus by tufts of distinct orange hair in the armpits of adult males (see photo).

In the coming days and weeks we will undoubtedly see more bat species and other amazing organisms. I will try to post updates from the field as often as I can, but it remains to be seen if my cellphone modem works in the areas were we will do our work. Stay tuned.

Mammalogist Jen Guyton examining a freshly caught Lander's horseshoe bat.

Mammalogist Jen Guyton examining a freshly caught Lander’s horseshoe bat.

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.

Mozambique Diary: Sylvan katydids of Gorongosa

Male Elegant sylvan katydid (Acauloplax exigua) in his typical resting position.

Male Elegant sylvan katydid (Acauloplax exigua) in his typical resting position.

A few nights ago, as I was walking towards my cabin along the edge of the Chitengo Camp, I heard a call of a cricket that I did not quite recognize. Cricket calls are unmistakable for their clean, almost melodious quality, very different from the call of a cicada or a katydid, which tend to be more “noisy.” But his call was very pure, almost bird-like, and it was coming from high in a tree. I expected to find a black, wide-winged Homoeogryllus cricket among the leaves, but to my delight the mystery caller turned out to be a gorgeous Blue-legged sylvan katydid (Zabalius ophthalmicus). This and a few related species produce some of the most pure tone, almost whistle-like calls, a rarity among katydids.

Sylvan katydids (Pseudophyllinae) are uncommon in this part of the continent. The greatest diversity of these insects is found in the rainforests of Central and West Africa, where most live high in the canopy. In Mozambique I expected to find only four species, and indeed found them all in Gorongosa (which of course is not to say that more are not to be discovered.) Virtually all sylvan katydids, true to their common name, are associated with forests and other woody habitats, and few are found in the open savanna.

Southern African sylvan katydids display two very distinct types of mimesis (camouflage). Species found in the canopy of broad-leaved trees (e.g., Ficus) are superb mimics of foliage, complete with leaf-like venation of their wings and fake fungal spots or other “damage.” During the day they rest with their wings spread flat against the lower surface of the leaf, and are absolutely impossible to find. (Interestingly, this type of behavior does not occur in any katydid species found in the New World – all North and South American katydids hold their wings in a vertical position, and during the day rest on twigs with their wings facing up in an imitation of a small leaf.)

Greater bark katydid (Cymatomerella spilophora)

Greater bark katydid (Cymatomerella spilophora) in the woodland of Gorongosa

The second group of species of Mozambican sylvan katydids are bark mimics. These species are associated with more open habitats, mostly miombo or mopane woodland, and spend the day resting on trunks of small-leaved trees, such as Acacia or Brachystegia. Their wings are held similarly flat against the bark, and their coloration is mottled, resembling the surface of the trunk. In addition, their legs are strongly flattened and covered with dense hairs, which helps them eliminate the shadow cast by their bodies.

One of the Mozambican species, The Common bark katydid (Cymatomera denticollis), is unusual among katydids in its ability to produce chemical defenses. Production of repellant chemicals has been documented in a few Neotropical species, but this is the first example of such a behavior in an African species. These insects, when threatened by a predator, fan their wings and reveal a brightly colored, red, orange, and black abdomen. At the same time a gland on their abdomen sprays a strongly smelling liquid. I have had no chance to look into the chemical composition of this substance, but its smell is very much reminiscent of that produced by their (unrelated) South American counterparts. In those katydids the repellant substances were identified as methylpyrazines, and I would not be surprised if the African species produced related compounds.

A song of the Blue-legged sylvan katydid (Zabalius ophthalmicus). Click here to listen to the recording: first played at the normal speed, followed by a fragment slowed down by a factor of 10 (for the katydid-challenged listeners, i.e., most males over 35).

A song of the Blue-legged sylvan katydid (Zabalius ophthalmicus). Click here to listen to the recording: first played at the normal speed, followed by a fragment slowed down by a factor of 10 (for the katydid-challenged listeners, i.e., most males over 35).

Female Elegant sylvan katydid, showing fake leaf damage and leaf-like venation on her wings.

Female Elegant sylvan katydid, showing fake leaf damage and leaf-like venation on her wings.

Sylvan katydids of Gorongosa in their typical daily resting poses: Blue-legged sylvan katydid (Zabalius ophthalmicus), Elegant sylvan katydid (Acauloplax exigua), Common bark katydid (Cymatomera denticollis) and Greater bark katydid (Cymatomerella spilophora).

Sylvan katydids of Gorongosa in their typical daily resting poses: Blue-legged sylvan katydid (Zabalius ophthalmicus), Elegant sylvan katydid (Acauloplax exigua), Common bark katydid (Cymatomera denticollis) and Greater bark katydid (Cymatomerella spilophora).

Mozambique Diary: Manticora

A male Monster Tiger Beetle (Manticora latipennis) killing one of his favorite prey items, a grasshopper (Humbe tenuicornis) [Canon 7D, Canon 100mm macro, 3 x Canon 580EXII]

A male Monster Tiger Beetle (Manticora latipennis) killing one of his favorite prey items, a grasshopper (Humbe tenuicornis) [Canon 7D, Canon 100mm macro, 3 x Canon 580EXII]

Things have been busy here in Chitengo, and I am struggling to find time to update the blog amidst the preparations to our upcoming biodiversity survey of the Cheringoma Plateau. But I simply cannot resist mentioning one of the most remarkable creatures that I have had the pleasure to meet in Gorongosa. Every biologist has a list of organisms that he or she is particularly keen on seeing at least once in the wild. My list is long, but a few days ago I managed to check off it Manticora, or the Monster Tiger Beetle.

With a name like this one would expect a rather extraordinary beetle, and one would not be disappointed. Named after a mythical beast with the body of a lion, head of a man, and the tail of a scorpion, the real-life Manticora may not be as monstrous, but it is nonetheless a stunning animal. It is the world’s largest tiger beetle (Cicindelinae), with a robust, heavily sclerotized body that easily reaches 65 mm in length. Its head, especially that of the male, is equipped with a pair of mandibles that would not look out of place on a stag beetle but, unlike the mostly ritualistic function of large mandibles in stag beetles, those of Maticora are very much functional.

The mandibles of a male Manticora latipennis are truly impressive. In addition to catching and killing prey, males use them hold and guard a female during copulation. [Canon 6D, Canon 16-35mm + an extender, 3 x Canon 580EXII]

The mandibles of a male Manticora latipennis are truly impressive. In addition to catching and killing prey, males use them hold and guard a female during copulation. [Canon 6D, Canon 16-35mm + an extender, 3 x Canon 580EXII]

Despite its size Manticora behaves in a way quite similar to smaller tiger beetle species. Its movements are agile, and it can run like hell and change direction in a split of a second; they cannot fly, however. These beetles hunt anything that moves, although prefer orthopterans, but unlike other tiger beetles it appears that the sense of smell rather than vision is their main tool for locating their victims. Once prey is located the beetle clasps it with its enormous mandibles and literally chops it to pieces. I watched it find and kill a large wolf spider – at first I thought that the spider would put up a fight, but about two seconds later what was left of the spider was a nicely masticated ball of tissue and a small pile of legs. After the main body was consumed the beetle picked the legs, one by one, off the ground and ate them, too. Interestingly, the beetle, which was a male and thus his mandibles ware particularly large, used its maxillae rather than the mandibles to pick up the leftover bits of prey, a behavior I have not seen before in a beetle.

A spider found by Manticora did not stand a chance – in a couple of seconds all that was left of the animal was a pile of body parts. [Canon 6D, Canon 16-35mm + an extender, Canon MT-24EX twin light]

A spider found by Manticora did not stand a chance – in a couple of seconds all that was left of the animal was a pile of body parts. [Canon 6D, Canon 16-35mm + an extender, Canon MT-24EX twin light]

Manticoras have a bimodal pattern of activity, hunting mostly early in the morning, and then again around sunset and, contrary to a frequently repeated misconception, they are not nocturnal. This is likely because of the competition from other, mostly nocturnal ground beetles (Anthia and Termophilum), which are also common here.

A male Manticora with prey [Canon 7D, Canon 100mm macro, 3 x Canon 580EXII]

A male Manticora with prey [Canon 7D, Canon 100mm macro, 3 x Canon 580EXII]

The discovery of Manticora in Gorongosa has also solved a small mystery for me. About a week ago I witnessed a strange sight – a very large antlion of the genus Palpares, an insect the size of a small bird, was slowly disappearing, head first, into a perfectly round hole in the ground. That just did not compute, and I had to see what was causing this behavior. I tried to pull the antlion out and something pulled back. But the mystery animal’s strength was no match for my mighty human strength, and I freed the antlion, but not before catching a glimpse of a large, flat head about the size and shape of a penny, disappearing deep into the perfectly vertical tunnel in the ground. Tiger beetles have larvae that behave in exactly this way, and now I am convinced that I stole the prey from a Manticora larva. Next time I see a similar tunnel I will try to find the larva and photograph it.

I have read in several places that the male Mantcora's enormous mandibles are not good at catching prey – not true, they are excellent killing devices! [Canon 6D, Canon 16-35mm + an extender, 3 x Canon 580EXII]

I have read in several places that the male Mantcora’s enormous mandibles are not good at catching prey – not true, they are excellent killing devices! [Canon 6D, Canon 16-35mm + an extender, 3 x Canon 580EXII]