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Mozambique Diary: Heroes, and what bugs them

Jen with her exciting catch

Jen with her exciting catch

One early morning, while on the Cheringoma Plateau, Jen “the Mammal Lady” Guyton came running into the camp. “We caught something really good in our traps!”, she announced breathlessly, sending the media team that was filming our expedition into a state of frenzied excitement. Everybody rushed to see the mystery animal, whose identity Jen refused to reveal. We scrambled through a spiny thicket and arrived at a place where she had set a large trap the night before. My imagination was running wild, and I was really hoping for a pangolin, or at least a baby aardvark. But the animal I saw was neither of these. At first, in the dim light I couldn’t quite make out the large mammal in the cage, and my first thought was of a small kangaroo, which would have been exciting if rather unlikely. “It is a pouched rat!”, Jen said proudly, and I felt all my hopes deflate like a punctured tire.

But my disappointment turned out to be grossly unjustified. To begin, the animal was actually very pretty. It was the size of a small cat, with a sweet face and slow, deliberate movements, quite unlike those of a house rat or any other rodent that I had ever seen. When Jen handed it a snack, it calmly ate it. Its tail was thick, half black and half white, which is a characteristic coloration of this species. Pouched rats (Cricetomys gambianus) are members of the family Nesomyidae, and thus not closely related to the rats that infest human houses, and derive their name from their ability to store food in large pouches in their cheeks. They can reach the weight of about 2 kg, and in some parts of Africa are hunted for their tasty meat.

Pouched rat (Cricetomys gambianus)

Pouched rat (Cricetomys gambianus)

In Mozambique, however, pouched rats play a very different role. The civil war of 1975-1992 has left many areas of the country infested with land mines, resulting in human casualties, and forcing people to abandon their land and houses. The removal of mines is an arduous process that normally requires the use of metal detectors or highly trained sniffer dogs. But in the late 1990′s Frank Weetjens, a Belgian mine-removal specialist, realized that pouched rats could make great mine detectors – they have an unparalleled sense of smell, and their calm nature and intelligence makes them easy to train. His organization APOPO set up a rat training camp in Tanzania, where young pups of pouched rats are taught to detect the smell of 2,4,6-trinitrotoluene (TNT), the main ingredient of land mines, and signal its presence to the trainer in exchange for a snack. After a 250-day long training the rats are flown into Mozambique, where they are used to systematically de-mine large areas still too dangerous for people to inhabit. Their efficiency in detecting land mines is nearly 100%, and their use in Mozambique has already allowed thousands of families to return to their homes and farmlands. It is not surprising then that in Mozambique they are known as Hero rats, a designation they fully deserve. In an even more amazing development, the pouched rats are now being used in Africa as sensitive and efficient diagnosticians of tuberculosis, a disease that affects many rural populations. Their incredible sense of smell allows them to differentiate between sputum of a healthy and an infected person at a rate and accuracy much higher than those afforded by traditional medical tests.

Epizoic earwig (Hemimerus sp.) on the fur of a pouched rat

Epizoic earwig (Hemimerus sp.) on the fur of a pouched rat

All this would be enough to make me worship pouched rats, but the animal we caught had a hidden entomological bonus. We had placed it a large container to take a few photos, and then we noticed dozens of large, brown insects running on its fur. One look and I immediately recognized them as something I had only read about before – they were parasitic earwigs! Earwigs are not insects that are usually thought of as something to be found on other animals, but members of the suborder Hemimerina are specialized parasites of rodents. They lack the large abdominal forceps of their free-living relatives and they are blind. Unlike other earwigs, they are also viviparous. On the body of the pouched rat they moved with an amazing speed, and their legs acted like clasps, allowing them to cling to hair and virtually swim through the mammal’s fur.

Epizoic earwigs (Hemimerus) lack the clasping cerci of their free-living cousins

Epizoic earwigs (Hemimerus) lack the clasping cerci of their free-living cousins

Adult parasitic earwigs (Hemimerus) have many nymphal characteristics, such as the lack of clasping cerci, wings, and wing musculature, suggesting that they are paedomorphic (reproductive stages that retain larval morphology.)
From the pouched rat’s perspective, having the earwigs is probably not too bothersome. These insects feed only on dead flakes of skin of the mammal, and thus act more as helpful exfoliants, rather than true parasites, and I also imagine that they provide an occasional snack.

All in all, the pouched rat in the trap turned out to be far more interesting than a baby aardvark would have ever been. (But I am still hoping to see one.)

An adult epizoic earwig (Hemimerus sp.)

An adult epizoic earwig (Hemimerus sp.)

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: It’s good to have my gear back

To celebrate the miraculous recovery of my photographic equipment from the clutches of South African Airways, today I took my new Canon 400mm for a short spin around the Chitengo camp. I usually do not photograph birds and mammals, but there are so many of them around that it would be a shame not to point a lens at some.

This Yellow baboon (Papio cynocephalus) got in our cabin this morning and stole our bananas. Just a reminder to keep our doors and windows locked, we are on their turf here.

This Yellow baboon (Papio cynocephalus) got in our cabin this morning and stole our bananas. Just a reminder to keep our doors and windows locked, we are on their turf here.

There is a small colony of Village Weavers (Ploceus cucullatus) near my cabin. This male was finishing his nest and frequently displayed if any female was around.

There is a small colony of Village Weavers (Ploceus cucullatus) near my cabin. This male was finishing his nest and frequently displayed if any female was around.

African Pied Crow (Corvus albus) is a handsome, intelligent bird, but for some reason birders tend to ignore this species.

African Pied Crow (Corvus albus) is a handsome, intelligent bird, but for some reason birders tend to ignore this species.