Zoo Attempt to Fertilize Komodo Dragon Fails

The last Komodo dragon in the United States has been returned to her exhibit at the San Diego Zoo without becoming fertile under a unique experiment attempted by zoological physiologists in November.

Sweetheart, the 55-pound female Komodo, was implanted with an experimental device that officials hoped would promote ovulation. She then would have been impregnated with semen taken and preserved from a male Komodo that died at the zoo in January, 1986, without ever having mated with Sweetheart during 10 years of cohabitation.

But, for biological reasons associated with the 18-year-old animal, most likely her advanced age, the Komodo did not show any significant increase in her hormone level, zoo physiologist John A. Phillips said Wednesday.

“She had a very minimal reaction but as to why she did not react more, there’s a lot of possibilities, the closest being that she is too old,” Phillips said.

Phillips nevertheless praised the new device that surgeons attached to the lizard for the experiment. A small intravenous-type tube was put under the lizard’s back, and connected to a bag filled with the hormone inside a small device about the thickness of a stack of four quarters and attached to the animal’s outside with surgical threads and tape.

“We could see it was working since the bag got smaller,” Phillips said. The device is a significant improvement over previous mechanisms to boost hormone levels in endangered lizards, which required surgery to place a bag inside an animal.

The frozen semen can still be used in the future, perhaps with a female Komodo in one of several European zoos if those animals can be ovulated with similar pumps, Phillips said.

Komodo dragons have not been bred in captivity outside of their native Indonesia. Only about 7,000 of the fierce-looking and intelligent lizards remain on four Indonesian islands.