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Los Angeles Zoo Uses Bird Test To Sex Komodo Dragon Embryos

DNA test to determine gender of bird embryos works on Komodo dragons.

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The Los Angeles Zoo is using a DNA test that was originally created to determine the gender of bird embryos on Komodo dragon embryos (Varanus komodoensis) in an effort to bolster the population of captive female dragons, the Los Angeles Times reports.

Currently, there are 71 male and 46 female Komodo dragons in North America and six lizards that are unsexed. Scientists want to have 75 males and 75 females, and the test would enable them to selectively hatch female eggs while preventing the male eggs from hatching.


To determine the sex, blood is extracted from a Komodo dragon egg with a needle and that blood sample is tested using the bird test at a laboratory to determine what sex the embryo is. The test is performed at the halfway point of the 260 day incubation period. The needle hole is then patched up with glue and placed back into incubator.

Ian Recchio, curator of reptiles and amphibians at the zoo told The Times that until the test was implemented, there was no way to tell the gender of the dragons that hatched out, which he said created a male heavy population. This is on top of the fact that male dragons in captivity are known to kill females, and the females also have often fatal complications during the time in which they are pregnant.


Scientists hope that the test will enable them manage the number and gender of the lizards that will help prevent the captive population from becoming inbred which can lead to hereditary disease. Another reason to control the gender is due to economics. The Komodo dragon is very expensive to keep in captivity. They are voracious eaters and grow very large, with some growing up to 150 pounds and 10 feet in total length.

The Komodo dragon is native to the Indonesian archipelago, found on the islands of Komodo, Rinca, Flores, Gili Motang, and Padar. They feed mostly on dead animals but are also well equipped to ambush and kill animals such as pig and deer. It is an endangered species, with an estimated 4,000 to 5,000 left in the wild. Komodo dragons are listed in Appendix I of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES).