Male vs Female Hamster: How to Tell the Difference

To tell a male hamster from a female, hold the hamster belly up in your hand and look at the anogenital distance, the gap between the anus and the genital opening. In a male the gap is longer, and an adult may show testicles. In a female the two openings sit close together. The steps below come from a veterinary school's handling sheet.

Size and temperament depend more on the species than on the sex. Syrian females tend to be the larger sex, and Campbell's and Roborovski males are the larger sex. Housing is where the sex matters most: a male and a female do not belong in one cage. If you are still pricing out a first hamster, see how much hamsters cost.

How do you tell a male hamster from a female?

The University of Bristol veterinary school teaches the palming method. Hamsters have only a very short tail, so the tail-lifting method used on rats and mice does not work.

1. Wake the hamster first. Hamsters are mainly nocturnal, and Bristol says surprising one while it sleeps will almost certainly get you bitten. Make some noise near the bedding so it comes out on its own.
2. Pick it up with your hand under its whole body, then use the other hand to help it feel secure. That is the lifting method the MSD Veterinary Manual describes.
3. Hold it in one hand facing you. Put your other hand over the top and turn it over to show the underside.
4. Use two fingers in a scissors action to show the genital area, then look at the gap.

A male has the longer gap, and an adult male has visible testicles. They can pull in, so a male may not show them every time you look (Bristol). A female has the shorter gap. Do not count on nipples to identify a female. Bristol says they only show on a female that is nursing or very young.

A vet can sex pups very early, from the anogenital distance and the pointed genital papilla in the male. If a hamster's sex is not clear to you, ask a vet to check it. Pet parents with a young hamster have a time limit: the MSD Veterinary Manual says to separate males and females before 8 weeks old, because hamsters can breed at a young age.

Scent glands

Syrian hamsters have scent glands on each flank that show as dark patches. The Louisiana Veterinary Medical Association calls them normal structures that mark territory and help in mating. A study of the flank glands found them better developed in males at every age it checked, round in adult females and oval in adult males. Roborovski hamsters have a gland in the middle of the belly. It is larger in males, according to the University of Michigan's Animal Diversity Web.

Are female or male hamsters bigger?

It depends on the species. The Louisiana Veterinary Medical Association gives adult Syrian weights of 95 to 150 g for females and 85 to 130 g for males, and says females tend to be larger. The ranges overlap, so weight alone will not tell you the sex of one hamster. Campbell's dwarf males are larger than females, and Roborovski males weigh more than females across the year (Animal Diversity Web).

Our page on dwarf hamster breeds covers the dwarf species one by one.

Are male or female hamsters friendlier?

The veterinary sources do not rank one sex as friendlier. The one temperament difference they give is for Syrians: females tend to be more aggressive than males (Louisiana Veterinary Medical Association), and adult females can be very protective of their space and sometimes fight (MSD Veterinary Manual).

Handling counts for more than sex. The MSD Veterinary Manual says a hamster handled gently from a young age is often easy to pick up and less likely to bite unless startled. Most bites come from a hamster that was woken or startled, which is why the wake-up step above comes first. For research background on social and aggressive behavior in rodents, Penn State's animal resource program has a guide on rodent behavior written for lab researchers.

Do female hamsters have periods?

Not the way people do. A female hamster has an estrous cycle of four days. The Louisiana Veterinary Medical Association says estrus and mating usually happen in the evening. As a female comes into estrus, her discharge is thin, stringy, and see-through. At the end of estrus it turns thick and cloudy. That discharge is normal. One study charted the daily rhythms of activity, body temperature, and metabolic heat production in golden hamsters.

The RSPCA says females in season give off strong pheromones that frustrate males, so it says not to house a female near a male. It adds that males mark territory with pheromones that stress other males nearby.

Can a male and female hamster live together?

No. They will breed, and the RSPCA strongly advises against mixing sexes. The MSD Veterinary Manual says hamsters are best housed alone, and that single housing is the safest choice except during breeding.

The RSPCA says Syrian and Chinese hamsters should always live alone. A care guide from Pets Corner says Syrians start to fight once they reach maturity, between 8 and 12 weeks old; see its page on Syrians. When hamsters share a cage and a fight starts, it can turn aggressive fast.

Dwarf hamsters can sometimes live in pairs or trios. The RSPCA says the group should be young litter mates, formed early in life, with no new members added later. Fights usually happen at night, so check for injuries each morning. Hamsters do not play-fight, and a fight means permanent separation into different cages. Give each hamster its own hide and equal access to bowls and wheels.

A roomy cage with several hiding places makes this easier. Our guides to the best hamster cages, Hamster Houses, and best hamster tubes cover the choices. Both sexes eat the same base diet. The MSD Veterinary Manual says a commercial rat or mouse pellet with 15 to 20 percent protein meets a hamster's needs, and treats should stay under 10 percent of the diet. Our page on the best hamster food has picks. The dietary needs of the hamster are set out in the National Research Council's nutrient chapter.

What happens if a male and female do end up together?

Separate them right away. If you think the female is pregnant, book a vet visit. Pregnancy lasts 16 to 17 days in Syrians, and the MSD Veterinary Manual says a normal litter is 6 to 8 pups. The manual advises extra bedding, a good diet, plenty of water, and a prenatal vet visit for the mother.

Leave a new mother and her pups alone for at least 7 days after birth, especially after a first litter. The manual says too much stress can lead her to abandon or eat the pups. Pups are weaned at 21 to 28 days. Breeding is best left to experienced breeders, because hamsters, females especially, can become aggressive and some carry inherited health problems.

Can hamsters change sex?

No. A hamster does not change sex. When two hamsters sold as a same-sex pair produce a litter, the first sexing was wrong. Check again with the steps above, or ask a vet. Wait to house hamsters together until you are sure, and house them apart if you are not.

How long do male and female hamsters live?

The Louisiana Veterinary Medical Association gives a lifespan of 1.5 to 2 years and does not split it by sex. Our page on hamster lifespan goes through what affects it. Researchers have studied sex and lifespan most in people, and one review of human studies covers minor differences in longevity between the sexes.

Sources

• University of Bristol Veterinary School, Handling a Hamster (clinical skills sheet CSL_H04)
• Louisiana Veterinary Medical Association, Biology of the Hamster
• MSD Veterinary Manual, Breeding and Reproduction of Hamsters
• MSD Veterinary Manual, Providing a Home for a Hamster
• RSPCA, Keeping Hamsters Together
• University of Michigan Animal Diversity Web, Roborovski hamster
• University of Michigan Animal Diversity Web, Campbell's dwarf hamster