AmphibiANS AND REPTILES
take a look at some of our recent work
The Gambia has a rich Herps fauna with 107 species comprising 33 species of amphibians and 74 species of reptile, including crocodiles, snakes, turtles, tortoise, terrapins, chameleons, worm lizards, monitors, and skinks. These are the species known to occur, but research in The Gambia on this group is limited and it is likely that additional species will be found in coming years.
how many species of crocodiles are there?
Many people are familiar with the West African crocodile (Crocodylus suchus) in The Gambia as they are widespread and easy to see in some places, e.g., Katchikally. Some people may tell you that they are the widespread Nile crocodile (Crocodylus niloticus), but the crocodiles in West Africa have recently been shown to be a new species and, as a result, the ecology of this species is mostly unknown as most of the information came from the wrong species! The situation with the two other species that could occur is even less clear.
The West African dwarf crocodile (Osteolaemus tetraspis) is officially extinct, having been lost at its only known site, Abuko (confirmed by extensive surveys in 2000). However, in 2010, our team was surveying vultures when we noticed a small croc that appeared to have the characteristic dark eyes of this species (C. suchus has pale eyes). One of our team, Ryan Fritsch, managed to get close to it and take pictures that we used later to confirm that it was indeed a dwarf croc. Since then, we have revisited the site regularly and have not only confirmed its continued presence, but we’ve also proven that the pond is a breeding site. We have also surveyed other water bodies nearby and believe that dwarf crocs may be present elsewhere.
Baby crocs are vulnerable to predation by a wide range of animals, including humans. The best way to make sure that some young survive is to “headstart” them. This involves taking some into protective captivity until they are almost mature and only vulnerable to larger crocs and hunting. Then they can be released into protected areas to establish/strengthen breeding populations. Our good friend Luc Paziaud at the Kartong Reptile Farm has prepared a headstarting facility and our aim is to collect some babies for him in the very near future. We have also prepared suitable forest sites for the release of the headstarted crocs.
The status of the third species, the African slender-snouted crocodile (Crocodylus cataphractus) is unknown. In the review of the status of this species, the IUCN does not list it as present in The Gambia (and it is not on the distribution map). However, we believe it is still present in some areas away from the coast. As this species is Critically Endangered (the last category before Extinct) it is vital that surveys are performed at the earliest opportunity and suitable conservation measures introduced if they are found.
“Despite reasonably comprehensive collecting in The Gambia,” until 2008 all that was known about Armitage's skink (Chalcides armitagei) globally came from 4 specimens, all collected in The Gambia. It was later shown to also occur in Senegal and Guinea Bissau in the same limited habitat (usually the transition zone between sandy beach and soil). It is rarely seen as it “swims” below ground almost all of the time and is easily confused with snakes, with a long snake-like body and only tiny legs.
Its very specific habitat requirements result in very limited distribution. The areas where it is found are under pressure from coastal development, which, apart from direct loss of habitat, is likely to fragment remaining populations. It is not known how significant the building of roads and walls etc., are in limiting the movements of this species, but this must be researched as the threat of urbanisation is ongoing. Future developments could then look at mitigation measures to prevent the local or even global extinction of this fascinating lizard. We continue developing our methods for studying this secretive species and are collecting records to map its distribution and assess its status.
As part of our project work, we make sure that our team collects information on any key species encountered and all of our staff are familiar with which species require special attention. This is particularly useful as we visit many of the key biodiversity hotspots in The Gambia. “Casual” recording is very useful in giving us a better idea of the distribution of many species, e.g., we recently doubled the number of sites in The Gambia known to have a Western green mamba (Dendroaspis viridis hallowelli) when we saw 2 at the waterhole we created in Pirang-Bonto Forest.
One of these mambas was the first to have ever been caught on a camera trap! Reptiles are not often captured on the cameras as they are cold-blooded so the temperature sensors on the camera traps do not trigger. Luckily for us, there were birds in the foreground of the image which triggered the camera. Our camera traps also caught several monitor lizards drinking due to bird activity. In the future, we will trial camera traps designed for cold-blooded species and set up arboreal cameras in an attempt to more efficiently survey reptiles!
In 2021 we plan to start Herps expeditions to use a wide range of techniques (e.g., drift fencing, torchlight surveys) to survey the Herps populations of different areas, including areas that have not previously been surveyed and the few areas that have (to allow detection of population changes).
We have had some other interesting findings with a range of Herps species, but as the work is ongoing, we are not in a position to publish yet. Our work with the Gambian agamas is particularly interesting. If you are interested in contributing, please ask for the details of one of our Herps tours.