New Arrivals: Black Tree Monitors

There’s been a black tree monitor baby boom at Lincoln Park Zoo! The zoo is proud to announce that it is now home to five tiny new reptiles, which all hatched between October 31 and November 2. While they will mostly live behind the scenes, one or two may be temporarily viewable after they settle in to their diets.

The five hatchlings are the first offspring of a four-year-old female and her mate, a pair recommended for breeding by an Association of Zoos and Aquariums’ Species Survival Plan®. Although the species’ conservation status is currently unknown, only 67 individuals exist at 29 accredited institutions, making this a significant birth for these “dragons of the trees” in managed care.

Black tree monitors, native to the Aru Islands off the coast of New Guinea, are predatory lizards. At the zoo, they are fed insects, waxworms, and mice. Young ones don’t feed immediately and can go for weeks without eating; these five have just started doing so, meeting a developmental milestone. The monitors are adapted to live in trees, with a prehensile (or grasping) tail twice as long as their body.

While one of the smaller members of their taxonomic family (Varanids), black tree monitors are considered incredibly intelligent. At Lincoln Park Zoo, they participate in their own care through operant conditioning. Just like other animals on grounds, they voluntarily shift into their habitats, allow keepers to weigh them, and join in veterinary exams.

Black tree monitor eggs are incubated for around 164 days. Once hatched, young monitors are slow to develop—they won’t even reach sexual maturity until they are 2 years old. They have a median life expectancy of 10–15 years. This is the first black tree monitor hatch at Lincoln Park Zoo in two decades.

Currently, the parents can be viewed in their habitats in the front section of Regenstein Small Mammal-Reptile House. If you’re lucky, you may be able to catch a glimpse of the juveniles at the zoo in a month or two. Their ultimate destination will be determined by the Black Tree Monitor SSP.