Habitat of Furcifer labordi in Andranomena (Madagascar)
Labordes’ chameleon (Furcifer labordi) has been known for some years as the world’s shortest-lived chameleon. Three scientists from Madagascar have now studied a previously relatively unexplored habitat of the species. The study was conducted in the Andranomena Special Reserve, located about 30 km north of the coastal town of Morondava in western Madagascar. The special reserve has a regrowth part as well as a relatively intact part of dry forest, which lies at altitudes ranging from sea level to 250 metres.
To estimate the population density of Furcifer labordi, the forest was divided into three transects each 150 m wide. At night, the chameleons were searched for with a torch and colour-marked with nail polish. The next day, a 5 x 5 m plot was marked around each site and at least 5 m away along the transect line. In all plots, the canopy cover was counted in percent, the thickness of the foliage layer on the ground and ground-covering plants in centimetres, the number of shrubs up to 1 m, the number of trees over 1 m and the number of felled and burnt trees. Five days after the first count, chameleons were again searched for and counted at night. In addition, insects were caught, counted and identified using light traps. Furthermore, raptor observations (Centropus toulou, Falco newtoni, Buteo brachyperus, Corvus albus and Accipiter francesii) were counted every 200 m along a 1400 m transect. Other predators such as snakes (Madagascarophis colubrinus, Leiohterodon modestus, Mimophis mahfalensis, Dromicodryas bernieri) were also counted by observation. Climatic data from the urban area of Morondava were recorded.
Statistical analyses showed that more Furcifer labordi were found in forest sections where the canopy was denser and the foliage layer on the ground was thicker, and where there were more trees overall. In the forest sections where no chameleons were found at all, significantly more felled trees were counted. As was to be expected, considerably fewer Furcifer labordi were found in the dry season than during the rainy season. Ten different families of insects were found, the most common being Homoptera (mainly cicadas), Coeloptera (beetles), Dermaptera (earwigs), and Lepidoptera (butterflies). Insect availability seemed consistent from February to May. More snakes were counted in February than in March, and the number of birds of prey did not differ throughout the observation period.
The authors consider whether the differences between the microhabitats preferred by Furcifer labordi and non-habitats could have an impact on the longevity of the species. Unfortunately, causality was not proven.
Variation longitudinale de longévité de Furcifer labordi et analyse de facteurs à l’origine de sa longue durée de vie dans la reserve spéciale d’Andranomena-Morondava, Madagascar
Ahy Nirindrainiarivony Philibertin Honoré Djadagna, Achille Philippe Raselimanana, Lily-Arison René de Roland
ESI Preprints 18, 2023