D. tinctorius 'Powder Blue'

Dendrobates tinctorius

Cuvier, 1797

Dendrobates tinctorius (tincs) are, by the family standards, typically a large, highly variable species of dart frog with known ranges throughout northern Brazil, the Guyanas and Suriname.  The name “tinctorius,” from the Greek for word meaning “to soak in dye” was so given because of stories that indigenous tribes would rub these frogs onto the feathers or plucked skin of baby green parrots causing new feathers to grow bright red or yellow, thus the common name for this species – the “dyeing” poison dart frogs.

Like other members of the Dendrobatidae family, strikingly vivid colors warn of the alkaloid-based poison excreted from their skins, which can paralyze or kill potential predators.  With the exception of azureus, which is somewhat “super-charged” the Pumiliotoxin B from the known and studied wild morphs of D. tinctorius, while effective against predation, is not as potent as that which is excreted by other members of the genus.

D. tinctorius are considered to be primarily terrestrial animals, as they are typically found on or close to the ground.  However they do climb and can be found in and among shrubs and trees as high as 20 ft (about 6 meters) above ground.

These are bold frogs, and can be territorial and aggressive, especially during breeding.  Males initiate breeding by calling, which when audible to humans (some morphs call more softly than others) is a light, bee-like buzz.  They compete with one another by engaging in short battles, leaving neither party any worse for the wear.  Females, on the other hand, have been known to fight brutally once a nearby male begins to call.  Death can occur if the combatants end up in water, in which case the they will attempt to drown one another.  Otherwise they will fight until one of them either feigns death by lying motionless (either by strategy or exhaustion), or retreats to an area that is not within sight of the dominating female, who would  continue to pursue her.  The after her victory winner will approach the calling male, and the courtship begins.  She will stroke his back and his snout, a signal that she is ready to breed.  The male will then lead her to an area concealing any flat, relatively smooth surface on which she will deposit her eggs.  The number of eggs in a clutch will typically range between 3 and 6.  Either or both parents will look after the eggs, keeping them moist with water collected in their cloacae.  The tadpoles will hatch after approximately two weeks.

Upon hatching the male will coax the tadpoles one or two at a time onto his back, where they will adhere with a special mucous.  They will remain on his back until he finds suitable water receptacles for them.  This can be anything from small pools on the ground formed by leaves, rock depressions, and hollowed nut pods, to tree hulls and phytotelmata.  He will repeat this until all of tadpoles have been delivered individually to a pool of some fashion.  This duty is typically performed by the male, however; females will occasionally transport tadpoles as well (see picture).  This is where their parental care ends.  Unlike their cousins of the genus Oophaga and Ranatomeya, the Dendrobates do not keep track of where they deposit their tadpoles, and they will not deposit unfertilized eggs for them to eat.  The tadpoles hunt, forage, and scavenge for themselves.   Fortunately they are opportunistic omnivores that can make a meal of anything from slime, decomposing leaves and other detritus to drowned insects and live insect larva.  If all goes well the tadpoles will morph into froglets after 60-90 days.

As is the case with D. auratus, D. tinctorius tadpoles unfortunate enough to find themselves sharing a pool with others will have to compete if resources, i.e. food and space, are limited.  This creates an “eat or be eaten” scenario as the larger, more aggressive feeders cannibalize other tadpoles enabling them to morph into froglets sooner than any others that may survive the competition.  Another mechanism for survival is the tadpole’s release of growth inhibiting hormones, which suppresses the growth of some, while allowing the continued growth of others.  This seemingly accomplishes two things:  Aids the beneficiaries of the emission in the overall competition for survival by giving them a size advantage.  It also staggers the morph rate of the surviving siblings, which potentially reduces the possibility of inbreeding.

On a number of occasions I have observed tadpoles being carried on a parent’s back for as long as 48 hours.  In such cases the parent would visit one pool after another in an effort to dislodge the tad, yet the tadpole appeared unable or unwilling to swim free.   This seems to have happened when the other water containers were already occupied by other tadpoles.  Eventually, when there were no other options the tadpole would dislodge.  Do tadpoles sense, perhaps chemically, the presence of others?  Do they have the ability to literally “hang on” until the parent relents and searches for more suitable accommodations?  Since tadpoles of some Dendrobatids are cannibalistic and have chemical defenses, this could be a tadpole’s way of avoiding these encounters.  The breeding habits of this family are highly evolved, so it would not be surprising if this were proven to be true.