HOPE CALLS FOR THE GOLDEN MANTELLA

Studies conducted at Chester Zoo provide new hope for the critically endangered, Mantella aurantiaca.

The golden mantella is critically endangered, with just three known locations where the species is assumed to remain in the wild, measuring a total area of just 10km2. However, the new findings spell fresh hope for the reintroduction of the many captivebred populations in the private sector.

Mantellidae

There are 16 species of Mantella, 11 of which are threatened, endangered or critically endangered. When data was recorded for most of these species, population numbers were decreasing rapidly, suggesting an even bleaker picture for the genus. All Mantella species are endemic to Madagascar and face the same threats of deforestation, agriculture and mining as many reptile and amphibian species on the island.

Sometimes referred to as Malagasy dart frogs, Mantellas share many similarities with the dart frogs of Central and South America. Many members of the Mantellidae family retain poisonous alkaloid toxins from their prey items. Their bright colouration is a warning sign for this toxicity and is known as ‘aposematic colouration’. However, other members of the genus use Müllerian mimicry, exhibiting the

The golden mantella

The golden mantella is a tiny orange to red frog measuring just 24mm and weighing less than 1g. Their easily recognisable colouration and endangered species status makes M. aurantiaca the most well-known of the mantellas.

The golden mantella is present in just three patches of highly restricted pandanus forest in Central and Eastern Madagascar. Here, they tend to spend much of their time in swampy locations, close to sunny clearings in the forest.

These frogs are diurnal and extremely seasonal in their behaviour. M. aurantiaca is relatively cryptic until the rains arrive in January when these frogs can be heard clicking to one another in search of a mate. Calls usually consist of distinct repetitive clicks at different frequencies. A clutch of 20 – 60 eggs are laid in damp leaflitter, where the tadpoles will develop before breaking free and being washed away into swamps and wetlands. It takes around 70 days for tadpoles to metamorphose and then a further 2-3 weeks for the froglets to develop their striking colouration.

The study

Although exports in the 1980s and 90s likely contributed to the decline of wild populations, the number of captive-bred collections around the globe provides a final lifeline for the species in the wild. However, reintroducing a species requires the captive animals to exhibit the same natural behaviours as their wild counterparts to

Hope Calls for the Golden Mantella ensure successful breeding and survival. In the space of very few generations, animals can become adapted to their captive environment. This can sometimes lead to healthier, hardier and less temperamental animals, better suited to captivity. However, if these changes prevent captivebred individuals successfully breeding with wild individuals, the viability for reintroduction becomes much less likely. For a species as endangered as the golden mantella, understanding these breeding behaviours is likely to be the last hope.

Researchers at the University of Salford and Chester Zoo have conducted an experiment to test

MÜLLERIAN MIMICRY

DEADLY: MADAGASCAN MANTELLA (MANTELLA MADAGASCARIENSIS)

UNPALATABLE: BARON’S MANTELLA (MANTELLA BARONI)

DEADLY: COWAN’S MANTELLA (MANTELLA COWANII)

UNPALATABLE: BEAUTIFUL MANTELLA (MANTELLA PULCHRA) the behavioural responses of captive golden mantella when presented with recordings of mating calls. These recordings were taken from a wild population, a first-generation population in Madagascar and a fifth-generation population at Chester Zoo. The researchers hoped to gauge how responsive the captive population were to the calls of wild individuals to better understand the viability for reintroduction. Recordings were then played back to three of Chester Zoos captive populations - one from a display tank and two which were kept in a facility away from the general public.