REPUBLIC OF CONGO May to June 2008

(FRENCH VERSION)

I and two Congolese graduate students spent the rainy season of 2006 camped in the swamp forest of northern Congo, near the village of Impongui, collecting amphibians and reptiles. During the month we spent in the field, maggots grew under our skin, I was bitten by a Forest cobra, and together we completed my 2005 survey of the herpetofauna of the Likouala (see publications page).

A lot happened in the year that followed. I started a job as an assistant professor of Biology at Whitman College, and also published a book, an account of my Congo fieldwork, up to and including the 2006 expedition to Impongui (see main page for details of the book).

The effect of the job was that it required me to teach during the rainy season, so that May-June was the only time I was free to return to the Congo. The result of the publication of the book was that it left me feeling I owed a return visit to the people of Impongui who feature so importantly in it, to present a copy to the village. In any case, there was more work to be done, and, as ever, the expedition's list of goals grew longer and longer. Ange ZASSI-BOULOU, who had come on the 2006 expedition as a student, accompanied me again, but this time as a director of logistics, and to help train our new student, Sylvestre BOUDZOUMOU. We were interested, for example, in seeing what difference the dry season made to the species we had collected in the rainy season.

Whiman College students expertly packed my crates of equipment and supplies in preparation for my departure from Walla Walla for the Congo.	Ange and Sylvestre, my Congolese students, unpacked those same crates a week later at our camp in the forest.

The difference between wet and dry seasons made Impongui almost unrecognisable. Places in what had been the middle of the river were now dry land. I started to seriously worry. The single most important thing I had planned to do this visit was to test the amphibians to see if they were infected with the fungal disease, Batrachochytrium dendrobatidis ("chytrid" for short), a skin disease thought to be a major factor in the worldwide decline of amphibian populations. The disease is thought to have originated in Africa, but so far only a handful of minor studies have tested African frogs for the disease. Certainly never in the Congo. The dry season in Impongui didn't look likely to appeal to amphibians. We'd come equipped with boxes and boxes of expensive sterile skin swabs. What if we didn't find any frogs at all?

The overflowing Likouala aux Herbes River in the rainy season, November 2006	Exactly the same spot in the dry season, June 2008

After a few anxious days of catching nothing, the frogs came through for us after all. In the course of a month we swabbed 192 individuals, representing 12 species. And there was more to the frogs of Impongui than just chytrid testing. The rarest frog I've ever collected was two individuals of Hymenochirus curtipes during my 2005 expedition. One day in June, 2008, we came across a muddy puddle in the forest which was absolutely swarming with H. curtipes. We swabbed 60 of them, finally calling it quits so as to conserve our supply of swabs.

Swabbing a frog (Hoplobatrachus occipitalis) to test for chytrid fungus infection.	Sylvestre quickly learned the skills needed to process specimens in our makeshift laboratory.
Me, catching frogs and malaria.	Hymenochirus curtipes (left) and Xenopus fraseri (right), collected from the same puddle.
This small mud puddle in the forest turned out to be absolutely teeming with Hymenochirus curtipes, the rarest frog I have ever collected.	Ange with a plastic bag containing about 20 Hymenochirus curtipes.

Frogs are very nice, in their own way, and important to study for many reasons, but what I really longed for were snakes. These dry conditions seemed ideal for finding lots of them. However, if the frogs had exceeded our expectations, the snakes were a bit disappointing. In spite of all our efforts, only three species were added to our 2005 and 2006 lists. Two of these species were obtained in unexpected ways, and, as explained below, had the distinction of being the best snake and the worst snake of the expedition respectively.

Demolishing a brick pile in Impongui village. Brick piles are often excellent sources of herps, but this pile turned out to be disappointing.	Sylvestre cutting plastic sheeting into strips to make drift fences for our pitfall trapline.
A single juvenile Lamprophis fuliginosus,a common House snake, was our only reward for moving all those bricks.	Pitfall traps can be useful for capturing leaf-litter lizards and toads, but snakes climb out of them easily... usually.
BEST SNAKE of the expedition. This very rarely-seen species, Polemon bocourti was actually small enough to get caught in a pitfall trap.	WORST SNAKE of the expedition! My first Mamba (Dendroaspis jamesoni), was donated by a villager who made really sure it was no longer dangerous by crushing its head to a pulp, chopping it into 8 pieces and then allowing it to rot for 2 days before presenting it to me.

RESULTS OF THE EXPEDITION

We found minimal difference in our Impongui species lists between wet and dry seasons. Our total list for June, 2008, was as follows: Amphibians: Amietophrynus regularis, A. camerunensis, A. gracilipes, Ptychadena perreti, Hyperolius nasutus, Cryptothylax greshoffii, Hoplobatrachus occipitalis, Arthroleptis sylvatica, Phrynobatrachus sp., Leptopelis brevirostris, Silurana epitropicalis, Xenopus fraseri, Hymenochirus curtipes; Lizards: Hemidactylus pseudomuriceus, H. mabouia, Mochlus fernandi, Trachylepis maculilabris, T. affinis; Snakes: Natriciteres olivacea, Dendroaspis jamesoni, Grayia smithii, G. ornata, Naja melanoleuca, N. annulata, Psammophis phillipsii, philothamnus dorsalis, Mehelya poensis, Lamprophis fuliginosus, Polemon bocourti, Calabaria reinhardtii, Python sebae.

As for all that frog swabbing, our swabs were shipped to a lab in Wisconsin for analysis, and many months later the results came back: 33 of our 192 frogs tested positive for chytrid. However, this result provided as many questions as answers. There was no apparent pattern to which frogs were infected. No species seemed more vulnerable to the disease than any other. And what did those few positives mean? Was chytrid, if present, doing any harm to the frogs of Impongui? One of the great mysteries of chytrid research is why it is that some populations of amphibians are devastated by it, while others seem healthy even though infected.

FUTURE PLANS

Sylvestre BOUDZOUMOU (sylvestrebooz[a]yahoo.fr) won a scholarship to Laval University in Quebec City. He's starting there in January 2010. Can you imagine arriving in Quebec City in winter after never having left the Congo before in your life?

Ange-Ghislain ZASSI-BOULOU (zabouangh[a]yahoo.fr) single-handedly established and now directs a herpetology lab affiliated with Brazzaville's Marien Ngouabi University. He and Sylvestre carry out herp surveys in southern Congo independently. All they need from me is an ongoing supply of tissue vials and frog swabs. And Ange continues to train other students in herpetology, including (so far) one Canadian.

Discoveries beyond simple faunal inventories are starting to emerge from our work together. Keep checking the publications page from time to time and you'll gradually see them appear.

THANK YOU!

The following organisations provided financial and/or logistical support:

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