How to Sex Baby Hamsters
When baby hamsters are about a month old, they can be weaned. Not only that, but baby hamsters are pretty precocious. You need to separate the brothers from the sisters or you will be ankle deep in baby hamsters before too long. This is, of course, easier said than done.
Please Pass The Microscope
One month old baby hamsters aren't even one inch long. It's hard enough to tell where they are, let alone what sex they happen to be. Unlike adult hamsters - where the sexual characteristics are amazingly obvious - the babies look virtually identical. Trying to figure out one of those Magic Eye puzzles is easier than trying to determine the sex of a baby hamster.
And baby hamsters will not be cooperative. They are live wires. They will wriggle, kick, scratch and scream bloody murder if you try to flip them on their backs and peer under their tails. They don't care about you looking at their privates - it's their bellies they are worried about. In the wild, if a hamster is flipped over on its back by a predator, it soon not a hamster any more but lunch. This instinct is well ingrained in the baby hamster.
So What Can You Do?
The least stressful way to sex a baby hamster is to beg, buy, borrow or steal a portable plastic connecting tube made for hamster cages. Most of them are made in many colors. You might not be able to get a colorless tube, but even yellow will work.
Put the baby inside the tube. You may just lay it down in the cage and wait for a curious baby to waddle in. Place your hand over the entranceway. Chances are, the other end will already be blocked. Then lift the tube and baby slowly and carefully over your head. Look up. You should be able to see the underside of the hammy baby. You should see two dots. One dot is the anus and the other is the genitalia. (See image at the beginning of this article) Females have their dots close together. Males have them further apart.
You will probably have to do a lot of comparing and rechecking each hammy baby. But placing them in a tube where they don't have to be flipped over will be a lot less stress on you and the hamsters. Good luck!