RIP: Castor, the Denver Zoo's Oldest Komodo Dragon

Castor, the oldest Komodo dragon at the Denver Zoo, has died. Castor was a 21-year-old male dragon whose father, Naga, once belonged to President George H.W. Bush. He was born in 1994 at the Cincinnati Zoo and came to Denver that same year. In his 21 years, Castor fathered seven baby dragons. His twelve-year-old son, Raja, also lives at the Denver Zoo.

We wrote about Castor in our 2014 cover story "Beauty of the Beasts," an article featuring Rick Haeffner, the zoo's curator of reptiles and fishes and the keeper of the Association of Zoos and Aquariums' stud book for Komodo dragons.

In that role, Haeffner was responsible for helping to make breeding recommendations for all of the Komodo dragons in all of the AZA zoos, including the Denver Zoo. In other words, Haeffner was the official overseer of dragon breeding — and he described the process like this:
"The prelude is pretty intense," Haeffner says. "He rakes her sides; he'll bite her." If the female isn't ovulating, she won't be interested. But if she is, she'll lay down next to him, lift her tail and sometimes even drape it over him. He'll deploy his genitalia, usually kept tucked away in his cloaca, and use one of his two "hemipenes" to do the deed.
That's right: Komodo dragons have two-headed penises. They also have toxic saliva, have been known to eat feral dogs and can grow up to ten feet long.

Castor lived at the zoo's Tropical Discovery exhibit, and staff say that the elder dragon statesman will be missed. Here's a statement about Castor's passing:
Denver Zoo is saddened to announce the death of “Castor,” a 21-year-old male Komodo dragon. Castor had exhibited a slow decline in the mobility of his back legs for the last six years, due to arthritis. Zoo staff provided Castor outstanding care through a variety of methods, including a treatment plan of physical therapy, pain medication and even acupuncture. Although these efforts prolonged his quality of life, [last] week he showed severe difficulty moving his back legs, causing animal care and veterinary staff to make the difficult decision to humanely euthanize him on the morning of Thursday, July 8, at Denver Zoo. Castor was one of the ten oldest Komodo dragons in North American zoos.

“Castor was a remarkable animal and he will be missed. Although this is never an easy decision, it was the right one. We’ll all miss him very much, but we’re glad he lived such a long, happy life here at the zoo. It was just his time,” says Denver Zoo Sr. Vice President of Animal Care & Conservation Brian Aucone.

Castor began showing signs of arthritis in his rear legs in 2009. Over the years, staff mitigated his pain through medications. In November 2013, he began regular physical therapy treatments with a local animal therapist. Last month, staff also introduced acupuncture. He initially responded well to all of his treatments, and veterinarians kept a close eye on his condition with regular radiographs on his joints.

Castor was born on February 2, 1994, at the Cincinnati Zoo and arrived at Denver Zoo in July of the same year. He was an offspring of Naga, a Komodo dragon given to former president George H.W. Bush as a gift from the president of Indonesia, and among only the second clutch of eggs to successfully hatch in the United States. He then sired two clutches of his own, resulting in seven dragons.

Denver Zoo is home to three other Komodo dragons: females Kristika and Anika, and Castor’s 12-year-old son, Raja.