Lorenzo's looking for a partner. He is in his prime, but the offer is very limited, and the few females available do not speak his language. Although he sings to them like mariachi, they seem immune to his charms. This Valentine's Day has been difficult for him. Lorenzo is a golden mantella from Madagascar (Mantella aurantiaca), a tiny Critically Endangered frog whose populations have been reduced to the point of requiring the rescue of some specimens to prevent extinction. Lorenzo was born in captivity as part of a breeding program. Researchers have just discovered that his dialect, shape, and color are different from wild animals (1–3). These findings could have fatal consequences for the survival of the species.
"Wild female mantellas don't seem impressed with the singing of our males. However, captive-bred females go crazy when they hear the call from wild specimens. It's like comparing my voice when I sing in the shower with that of Barry White", jokes Dr. Gerardo Garcia.
"Wild female mantellas don't seem impressed with the singing of our males. However, captive-bred females go crazy when they hear the call from wild specimens. It's like comparing my voice when I sing in the shower with that of Barry White"
Gerardo is a curator at Chester Zoo and one of the researchers in charge of the reintroduction programs in Madagascar. In recent studies, Gerardo and his colleagues have identified potential incompatibilities of captive animals aimed for reintroduction. They are also investigating ways in which to reduce such incompatibilities. It's the closest thing to designing a Tinder for endangered frogs. "We quickly realized that wild populations were very different from the specimens of the breeding program, and we decided to investigate the implications of these differences on their conservation program," Gerardo adds.
Golden frogs have two criteria for mate selection. On one side, the call: a good repertoire of "clicks"(Figure 2) (see video for reference) is needed, or females will not know that you exist. And on the other hand, obviously, the looks: females look for colorful and physically attractive males. Their dark orange, almost red skin not only helps them to attract females but, most importantly, keeps predators away by warning them of their toxicity. Without this effective alarm system, they become jumping gummies for lizards.
Without their effective warning system, they would become jumping gummies for lizards.
The very few places in which these frogs can be found are mating battlegrounds. Loads of strong males stand on the edge of the ponds calling and fighting frantically with each other. "Obviously, our feeble and pale frogs would have no chance in this competition," says Gerardo (Figure 1).
The low density of animals in Madagascar's wild populations called for urgent human intervention to ensure the long-term survival of the species. With the increasing demand for these frogs in the pet trade during the early 2000s (4) and a rampant habitat loss in their native forests (5), a captive breeding program was established with breeding populations both in Madagascar and abroad (6). Conservationists are trying to maximize the genetic lines available through selective breeding to strengthening their delicate state. In order to do so, the introduced animals must speak the same dialect and be attractive to the local ones. Objectives in which Gerardo and his team are already working.
To stimulate these little frogs, the researchers have designed a large setup with a speaker system that introduces various sounds, including wild male calls, as well as a repertoire of noises found in their natural habitat. Bioacoustic samples have been taken in their environment to ensure that music played in this frog club includes only the best vibes (Figure 4). The soundscape offers the perfect motivation for the frogs in the breeding program to improve their tuning. "Our males get very pissed when they hear the call of a wild male; it is evident they recognize their limitations," tells us Gerardo, who hopes that the frogs will learn to imitate the calls of the wild specimens.
Additionally, the newly designed setup becomes a frog training center thanks to the different speakers' locations, which stimulate the frogs to move from one side to another to defend the territory. A newly modified diet supplemented with carotenoids works as makeup to enhance the coloration and make them more similar to the wild conspecifics.
After the treatment is completed, the researchers trust that the frogs will be ready to integrate into Madagascar's wild forests.
The golden mantella plays a vital role as a bioindicator. Its presence implies the ecosystem is relatively intact and full of life. Golden mantellas live alongside other threatened species such as the indri, the fossa, or the aye-aye.
Unfortunately, the golden mantella is just an example of the impact of habitat loss, alteration, and fragmentation caused by human activities over the past few decades. Madagascar is the third country with the highest biodiversity index, where also 80% of its species are endemic (7). However, Madagascar also remains one of the countries with the most significant loss of forests. Today, natural resources are extracted unsustainably for the manufacture of luxury furniture and mobile phones. Meanwhile, the Malagasy population remains one of the poorest in the world.
Solving inequity problems, poverty and deforestation require focusing on this forgotten island with little international attention. Actions required include new legislation, sustainability agreements, and fair trade, among others.
In addition, small actions such as mobile recycling or making sure that the furniture we buy is made of wood extracted from sustainable forests also count to reduce the demand for resources extracted from Madagascar's forests. Actions needed to ensure Lorenzo has a wild home to return to and a Valentine to court once he recovers the wild touch.
Madagascar is the third country with the highest biodiversity index, where also 80% of its species are endemic.