Conservation of the golden mantella in Madagascar: Integrating in situ and ex situ research

The greatest threats to biodiversity in Madagascar are habitat destruction, fragmentation and climate change. Complementary in situ and ex situ research can aid conservation because many aspects of natural history that can usefully inform conservation measures are difficult to study in the field. The golden mantella is an excellent model as it is unique in that it is a charismatic, high profile Critically Endangered amphibian, but is abundant in captivity and highly suitable for ex situ research. In situ research in a new protected area of Madagascar found surface temperature, litter coverage and the number of tree roots were the most important predictor variables associated with quadrats occupied by golden mantellas. Microclimatic measurements made in the field informed the design of the replicated climatic-controlled enclosures (Froggotrons) for golden mantellas at Paignton Zoo.

Froggotrons revealed golden mantellas had a bimodal activity pattern during daylight hours even under different temperature regimes. At lower temperatures (16 ºC - 19 ºC) mantellas were overall less active than those at higher temperatures (20 ºC - 25 ºC), but the phasing and bimodal nature of the activity rhythm was the same under both temperature regimes. Most activity occurred when humidity levels exceeded 85%. Golden mantellas were most active, spent most time in the open and less time on leaves at 21.5 ºC. Where temperature deviated either way from 21.5 ºC there was an associated decrease in activity and an increased tendency to hide in leaves. Results also show that even under optimum temperature and humidity regimes less than 50% of the frogs were active in open areas at any one time. Ex situ results have been used to assist with the design and timing of field population assessments and shed light on issues concerning imperfect detection when applying models to assess abundance. Species distribution modelling results suggest a potential south-eastwardly shift away from current distribution range and a decrease in suitable habitat from 2110 km2 under current climate to between 112 km2-138 km2 by the year 2085. Golden mantella research is a new development in the area of collaborative, complementary conservation. Integrating in situ and ex situ research may help mitigate the multi-faceted and synergistic threats to biodiversity in Madagascar.