Male dyeing poison frogs deposit their tadpoles in waters with cannibalistic conspecifics.
Dyeing poison frogs (Dendrobates tinctorius) are one of several frog species that care for their young up to a point. The male of the species carries its young on its back until it can find a suitable pool of water to deposit them, but it is the choice of pool that has scientists scratching their heads. According to a paper published in the journal Behavioral Ecology and Sociobiology, the male frog would just as soon deposit its young in a pool with conspecific tadpoles already occupying the body of water, even if the larger tadpoles would just as soon eat the smaller tadpoles after the father deposits them.
Scientist Bibiana Rojas of the University of Jyväskylä in Finland conducted the research in the forests of French Guiana and found that the male frogs, if given a choice, deposit their tadpoles in water-filled cavities in tree holes or palm bracts where there are existing tadpoles rather than in bodies of water with no tadpoles.
Rojas thinks that the bodies of water already occupied with tadpoles signal to the male frog that the water features suitable conditions to the survival of his brood, even though there is a likely risk of cannibalism from the existing tadpoles in the water.
“The presence and the size of conspecifics influence parental decision-making in the context of choosing a rearing-site for their offspring,” Rojas said in a statement. “Apparently strange parental decisions, such as depositing offspring with large cannibals, may ultimately not be that strange."
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Rojas likens the decision as a gamble the male frog is willing to take to ensure that the water is safe for his brood, even though there is the presence of cannibalistic tadpoles in the water. She believes that the amphibian thinks an unoccupied pool of water might mean that it is not suitable, or perhaps the presence of water is not stable enough to sustain the life of his brood for the duration (two months) of their metamorphosis. If the tadpoles are not eaten in the pool, then the male frog made a safe bet versus taking the chance with a pool of water drying up.
Dendrobates tinctorius, at around 2 inches in length, are one of the larger species of poison dart frog. They are prevalent in parts of Guyana, Brazil, Suriname and French Guiana. Mildly toxic in the wild, the dyeing poison frog has a black body with irregular yellow or white stripes running along its back, legs, chest and belly.