National Geographic : 2015 Jul
PHOTO: JOEL SARTORE This painted terrapin (Batagur borneoensis) in breeding colors was photographed at the zoo in Omaha, Nebraska. A genteel disquisition on love and lust in the animal kingdom Basic Instincts River terrapins try hard to be fruitful and multiply. Males use their bold breeding colors to entice mates, and their toenails to keep sex partners in their grasp. Females grow larger than males, the better to carry many big eggs. In mating season they couple liberally. Then females travel long distances, sometimes braving salt water, to sandbanks where they lay and bury several clutches of eggs a year. Despite such valiant efforts, five of the six species in the terrapin genus Batagur are critically endan- gered, says Rick Hudson, president of the Turtle Survival Alliance. Terrapins lose habitat to sand mining and die as bycatch in fishing nets. Eggs are snatched from nests, to eat or sell; adults are shipped to China, where they’re a banquet delicacy. Even temperature can influence survival: The sex of birds and mammals is determined by chromo- somes, but the sex of many turtles is influenced by temperature during incubation. Often hatchlings from cooler settings will be male; from warmer ones, female. When captive-breeding programs have kept eggs too cool, Hudson says, they’ve yielded few or no females, which typically lay hundreds of eggs in a lifetime. Conversely, the advance of climate change could mean warmer incubation locations, a preponderance of females—and a shortage of baby daddies. —Patricia Edmonds HABITAT/RANGE Estuaries in Southeast Asia CONSERVATION STATUS Critically endangered OTHER FACTS Females lay eggs in nests about 12 inches deep. At dif- ferent depths, eggs incubate at different temperatures. Too Hot to Handle In mating season terrapins couple liberally. Then females travel long distances to lay eggs.