Golden poison frog

Name and taxonomy

Charles Myers, John Daly and Borys Malkin described the species in 1978. The name terribilis refers to the deadly toxin in the skin. Myers worked from hundreds of specimens taken at Quebrada Guanguí and La Brea. He also kept a colony of 18 frogs at the American Museum of Natural History. That colony gave the first observations of the frog's breeding. The paratypes were collected in February 1973 near the junction of the Guanguí stream and the Patía river.

The species belongs to the genus Phyllobates in the poison dart frog family, Dendrobatidae. English names include golden dart frog, golden poison arrow frog and golden poison dart frog. In Spanish it is the rana dorada venenosa, and German names call it the terrible leaf climber. Some of these names are misleading, because the frog is used on darts, not arrows, and it does not climb.

Evolution and relatives

Dendrobatidae holds about 175 species, and most are tiny, some no bigger than a fingernail. The golden poison frog is the largest of them. Its closest relatives are the other Phyllobates species, such as P. aurotaenia, P. lugubris and P. vittatus. Those species carry dark spots or stripes, while the golden poison frog is one solid colour as an adult. Only three frogs in the world carry batrachotoxin, and all three are Colombian Phyllobates.

The same toxin turns up in a few birds of Papua New Guinea and in four Papuan beetles of the genus Choresine. That pattern suggests the frog does not make the poison itself but gathers it from its food. Its poison is about twenty times stronger than that of any other dart frog. Some Dendrobates frogs modify a toxin from their food, and this frog may do the same, but that is not proven. Like other poison frogs, it probably carries a protein that binds the toxin and keeps it from poisoning itself.

Appearance

An adult is one bright colour from nose to toe. Yellow is the most common, from pale to deep gold, and it gives the frog its name. Frogs at La Brea and La Sirpa are mint green, metallic green or even white, and they are the largest form. Orange frogs live near the yellow ones at Quebrada Guanguí. A captive line called orange blackfoot has dark marks on the feet, throat and rump.

Young frogs look quite different: mostly black with two golden stripes down the back. The black fades, and the frog has its adult colour at about 18 weeks. Body length runs from 4.7 to 5.5 centimetres, and the larger figures are usually females. Wikipedia gives a maximum of about 6 centimetres and nearly 30 grams. Females are usually larger than males.

A bone plate juts from the upper jaw and looks like a row of teeth, but the frog has none. The middle toe is longer than the outer two. The skin is smooth and moist, as in other frogs, and its colour is a warning to predators.

Habitat and range

The frog lives only in the Chocó rainforest on the Pacific coast of Colombia, in the departments of Cauca and Valle del Cauca. The whole range covers less than 5,000 square kilometres. Most frogs live along the upper Río Saija drainage, near Quebrada Guanguí and at La Brea. The river splits the population, with separate groups on its east and west banks. Within that small area the frog is common.

The land is hilly lowland forest between about 100 and 200 metres above the sea. It is one of the wettest places on Earth, with 5 metres of rain a year or more, and at least 1.25 metres. The frog does best at 26 °C or warmer and at 80 to 90% humidity. The ground there is wet gravel with small saplings and little leaf litter. The frog stays on the floor, but it needs standing water nearby for its tadpoles. It is known only from primary forest, so a cleared or regrown patch probably does not hold it.

GBIF holds records from 4 countries, but nearly all come from Colombia. The records from Brazil, the United States and Japan are probably captive animals.

Diet and hunting

The frog eats insects and other small invertebrates. Its main prey are ants of the genera Brachymyrmex and Paratrechina. It also takes termites, beetles, mites and flies. It hunts by ambush and takes larger prey for its size than most dart frogs. It will not usually attack an insect bigger than an adult cricket.

The strike is a single fast movement that is hard to follow with the naked eye. A long sticky tongue pulls the prey into the mouth. Captive frogs learn fast, and they rush to the front of the tank when the lid opens. Tadpoles eat algae, mosquito larvae and whatever else they find in their pool.

The diet is also the source of the poison. Frogs fed on shop-bought insects lose their toxin over time. Scientists suspect a small beetle of the family Melyridae, because a related beetle makes the same toxin.

Behaviour and social life

The frog is active by day and lives entirely on the ground. No one has seen it climb, in the wild or in captivity. It sits on the soil or a few centimetres up on a root. Most dart frogs are shy and quick to hide, but this one sits in the open. When something approaches, it moves away rather than hiding. Its poison probably explains this boldness.

Wild frogs live spaced out, not in dense groups. Captive frogs tolerate crowding with little aggression, unlike many relatives. Most disputes are between frogs of the same sex. Females wrestle over males, and males wrestle over territory. Fights involve calling, chasing and wrestling. The size of a wild frog's home range is unknown. Relatives such as P. aurotaenia are far more territorial, so the golden poison frog seems the calm one in its genus.

Communication and senses

The male sings a long trill to court a female. The call lasts 6 to 7 seconds, then repeats in a short 2 to 3 second version. It is an even run of notes at about 13 beats per second and a pitch near 1,800 hertz. That pitch is lower than the calls of most related frogs.

The frog also uses body language. A push-up shows dominance, and a lowered head shows submission. An excited frog taps its long middle toe, both when it hunts and when it courts. Before laying, the pair stroke each other's head, back, sides and vent.

Like other frogs, it hunts by sight and reacts to the smallest movement. The skin itself is a signal, a bright warning that predators learn to read.

Reproduction and life cycle

The frog is thought to breed all year. Both sexes take several mates. In captivity each breeding involved one female and two or more males. Egg laying is a fast scramble under cover of plants, and it has never been seen in the wild. The eggs are fertilised outside the body and laid on the ground under leaf litter.

A clutch holds fewer than 20 eggs. In captivity the eggs hatch after 11 to 12 days, and a whole clutch takes 2 to 4 days to finish. The tadpoles wriggle onto the mucus on a parent's back. The adult carries them to a water-filled tree hole or the pool inside a bromeliad. Only three wild males have ever been caught with a clutch on their backs. Once the tadpoles are in the water, parental care ends.

The tadpoles graze algae and eat mosquito larvae, then go through full metamorphosis into froglets. Captive froglets start eating fruit flies less than 10 days after they leave the water. A young frog keeps its black and gold stripes until about 18 weeks. Captive frogs have lived up to 5 years, and wild frogs probably live 5 years or more. No wild eggs have ever been found. Whether the frogs press vent to vent during mating is still unconfirmed. The tadpole stage probably takes several weeks, as in other dart frogs, but no source gives a figure.

Predators and threats

An adult has few enemies, if any. One small snake, Leimadophis epinephelus, resists several frog toxins including batrachotoxin. It eats young frogs without harm, but it is too small to take an adult. A predator that mouths an adult frog is likely to die. Animal Diversity Web credits this safety with the frog's long life for its size.

The real threat is the chainsaw. Forest inside the tiny range is being cleared for farming. The frog is now known from fewer than five areas. Poaching for the pet trade was once a serious threat. Captive breeding has cut the demand for wild frogs, and the IUCN now rates that threat as small. The chytrid fungus that has hit many tropical frogs is not named as a threat in any source read here.

Population and conservation

The IUCN Red List rates the golden poison frog as Endangered. No population count exists, and the species is abundant where its forest still stands. Its whole range is under 5,000 square kilometres, so a few clearings can remove a large share of it. The population is split into groups on either bank of the Saija, which may limit gene flow.

Tesoros de Colombia, a Colombian breeder, floods the pet trade with cheap captive frogs. The aim is to make a poached wild frog worth too little to catch. Captive frogs are legal, non-toxic, healthier and cheaper, so demand for wild ones has dropped. The IUCN estimates that most frogs sold as pets now come from captive lines. iNaturalist holds 458 observations of the species.

Relationship with humans

The Emberá and Cofán peoples use the frog to poison hunting darts. A hunter holds a live frog near a fire, and the heat makes its back sweat poison. Darts wiped across the skin stay deadly for two years or more. The web notes say one frog can coat 30 to 50 darts. The darts bring down small game, and they may once have been used in war.

Touching a wild frog is dangerous. Toxin rubbed onto the face has caused a burning feeling that lasted for hours. Myers estimated the lethal dose for a person at 2.0 to 7.5 micrograms. In mice the subcutaneous LD50 is 0.2 micrograms per kilogram. Researchers are testing the toxins as muscle relaxants, anaesthetics and heart stimulants. The frog is a popular vivarium animal because of its colour and its bold manner. Captive frogs show no aggression towards people, and the only risk is the skin of a wild-caught animal.

In culture and myth

In Emberá tradition, the frog is called kokoi, and French speakers still know it as the kokoï de Colombie. In the Chocó, the frog is part of hunting life rather than of story, and its poison is the point. The Emberá and Noanamá are the peoples most often named as users of frog darts.

Outside Colombia the frog is famous for one number: the count of people a single frog could kill. Wikipedia gives 10 to 20 people, or up to two bull elephants. Popular articles often say about ten adults, but that is a common claim rather than a measurement. The name terribilis, the terrible one, has stuck in German as the schrecklicher Pfeilgiftfrosch. The story of its discovery in 1978, when Myers and Daly first handled it, is retold by the American Museum of Natural History.