How to Determine the Sex of an Ostrich. Ostriches are part of the ratite family which include other flightless birds like the emu and kiwi. The male ostrich has two testicles and a phallus. The female ostrich has only one ovary (left) and a reproductive track with a ****oris on the ventral cloaca (posterior opening or vent.) Determining gender of ostriches is called "vent sexing." However, recombinant DNA sex testing is fast becoming more popular.
Check the sex of the ostrich chick when it is between one and two months old. The sex is more difficult to determine in younger chicks. Older ostriches frequently require restraining and an internal examination to determine sex.
Pull the tail of the chick (with the chick standing or being held by another person) and apply pressure to the cloaca (pushing lightly from the bird outward.) Once you turn the ostrich's cloaca (or vent) slightly inside out, you should be able to see if there is a phallus present on the chick.
Repeat the process with several ostrich chicks if possible to better recognize the differences and to master the steps for chick "vent sexing." This is by no means a fool proof method and the phallus is still difficult to see in some ostrich chicks.
You may also do recombinant DNA testing (using a blood, feather or eggshell sample) on birds any age and the test is over 99 percent effective. Many ostrich farmers prefer DNA testing and it's quickly replacing the more difficult physical method. DNA Sexing Kits cost between $20 and $25. Contact Zoogen (also home of the North American Ratite Registry.)
Ostriches mate around three to four years of age and several hens will mate with one dominant male. Ostriches reach their full height when they're around six months old. Determining sex at that age would be an ordeal indeed since full height can be up to 10 feet tall. Plus, a full grown ostrich weighs at least 200 lbs, frequently getting over 300 lbs.