Investigating dry forest reptiles using unconventional methods
Unusual methods of tracking and identifying reptiles are being used in North West Madagascar. ‘Invisible’ UV nail polish and fluorescent powder are making it possible to study chameleons and snakes without making them more conspicuous to predators.
Reptiles can be difficult to study. Many are cryptic, have complex life histories, and/or live concealed lives in inaccessible areas. They can also be challenging to capture and handle. Another problem is the expense of the equipment required: radio telemetry equipment, for example, can be prohibitively expensive. Studies of reptiles in Mariarano Classified Forest, a large block of intact dry forest in North West Madagascar, have overcome these problems using novel low-tech approaches.
Temporarily marking Chameleons with ‘invisible’ nail polish
One of two species of chameleon occurring within the Mariarano forest is Angel’s Chameleon (Furcifer angeli), a species endemic to the dry forest of western Madagascar. Population and behavioural studies require that we mark individuals. We used nail polish. Specifically, we used ‘invisible’ UV fluorescent nail polish to mark the chameleons. This is hard wearing and comes off when the animal sheds its skin, but, once dry, is only visible under black light. When tested with a spectrometer, the reflectance of the ‘invisible’ nail polish was only marginally different to that of unmarked skin, which suggests that this polish does not increase animals’ conspicuousness to predators.
Tracking the Malagasy Giant Hognose with fluorescent powder
Investigating the daily habitat use of a large, aggressive snake is difficult. Once captured, a snake is measured, weighed, sexed, and marked for future identification. Marking can be done via scale clipping or the injection of a passive integrated transponder (PIT) tag. The snake is then placed into a snake bag and coated with UV fluorescent pigment powder before being released. Again, we used the most inconspicuous coloured pigment powder to minimize the extent to which we were making them more conspicuous to predators.
At night, we use a black light to follow the luminous snake trail to provide a detailed record of the snake’s movements during its most active hours. As with other studies tracking reptiles using fluorescent powder (see eg Furman et al 2011 and references therein), we have found that this is both a useful and cost-effective technique for studying short term movement patterns and habitat use in Leioheterodon madagascariensis (see Figure 1).
Chips for everyone
In 2013, we began PIT-tagging individuals in species likely to be the subject of future research at the site, namely Giant hognose snakes and Uroplatus leaf tail geckos. We used a new type of mini PIT tag (8mm ST04 mini chip) with a Halo© MID06 Scanner, generously donated by Zoological International Limited (www.tortoisesdirect.co.uk). These mini-PIT tags will allow us to follow individual animals over multiple years.
With future plans that include night vision equipment and a drone, reptile research at Mahamavo will continue to be a proving ground for innovative tracking methods.
We thank DREF Mahajanga and MEF in Antananarivo for permits and permissions, Monkfield Nutrition for the donation of equipment, especially the ‘explorariums’, infra-red temperature guns and snake bags, and Operation Wallacea and DBCAM for providing funding and infrastructure. We thank the people of Mariarano for welcoming us back year after year.