Podocnemis unifilis Troschel, 1848, "im Rupununi und Takutu" (rivers in Guyana). No subspecies are recognized.
OTHER COMMON NAMES
English: Terecay, yellow-headed sideneck, yellow-spotted Amazon turtle; Spanish: Tracaja.
Yellow-spotted river turtles are large sideneck turtles, with a maximum shell length of 26.8 in (68 cm), an oval carapace bearing a low keel on the second and third vertebral scutes, and a slight medial indentation anteriorly. Only a single barbel is usually present under the chin. Juveniles have yellow-orange spots on the head.
These turtles occur in the tropical lowlands of northern South America, including the Orinoco and Amazon River basins.
Yellow-spotted river turtles inhabit freshwater rivers, streams, lakes, ponds, and flooded forests.
These turtles frequent rivers and large lakes during times of low water, but during the rainy season they migrate far into flooded forest areas. Females migrate to sand beaches along the main river courses to nest, and bask on the shoreline prior to nesting season.
Primarily herbivorous, this species feeds on the fruits of riparian trees, water hyacinths, and grasses. They also occasionally eat clams and dead fish.
Nesting season is timed with the period of low water and hence varies geographically, occurring in late January to early March in Venezuela, July to December in Colombia, October to February in Peru, and June to July, September to October, or during December at Brazilian sites. Females typically emerge to nest on sandbars just after dark, and excavate and cover their shallow nests only with their hind limbs. The eggs are elongate and average about 1.8 by 1.2 in (4.5 by 3.0 cm), and 0.9 oz (25 g). Clutch size ranges from four to 49 eggs, 20-30 being usual, with larger females producing larger clutches. At least two clutches may be produced each season. This species exhibits temperature-dependent sex determination, with warm temperatures (greater than 89.6°F [32°C]) producing females, and cool temperatures producing males.
Although listed as Vulnerable, this species is still exploited by local people. Females are captured on nesting beaches, fished for with hooks, and speared from the water, and eggs are harvested from nests.
SIGNIFICANCE TO HUMANS
Adults and eggs are harvested for human consumption. ♦
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