Male or Female? Unlike some other species of animals, rats have many distinct differences between the males and females. The following sections will break down these differences for you in hopes to aid you in choosing the best kind of rats for you and your lifestyle. A sleek, smaller female next to a larger, stockier male. Males... Males are generally twice the size of female rats (average weight 20oz.) Some males will have a tendency to urine mark their territories more often than females do. To remove this behavior, you can have a male rat neutered. Male rats can tend to have a musky odor. Neutering them will greatly decrease this odor. Males produce an oil called "buck grease" from glands on their backs which can turn the color of their hair in that area, yellowish-orange. If this area becomes considerably oily, you may want to bath them. Neutering greatly reduces the production of this oil. (See "Should I Spay/Neuter my Rat?" located in this Guidebook to learn more about this subject.) Males have coarser hair, unless they are neutered. Males can be harder to introduce to one another, unless they are neutered. It's always best to get brothers from the same litter at the same time. Several males together can be more aggressive with one another as opposed to a group of females together, especially throughout the hormonal stage in their life (from 3-12 months) when their hormones are raging. Neutering can fix this behavior. (See "Should I Spay/Neuter my Rat?" located in this Guidebook to learn more about this subject.) Unlike their playfulness in youth, as adult rats, males tend to be much more laid back and lazier than females. They will generally be happier snuggling on your lap as opposed to running around and playing games. Males generally love to be petted and scritched and held, unlike females who usually won't hold still long enough for such things. Many people prefer males because of these reasons. Males are more prone to obesity. A male will (almost) always be dominant to any females. Males are identified easily from about four weeks of age, due to their rather large scrotum. Males also have no nipples. If you find the male scrotum to be too offensive, you can always have a male rat neutered. (See "Should I Spay/Neuter my Rat?" located in this Guidebook to learn more about this subject.) The male rat. Females... Females are generally smaller and sleeker in size (average weight 13oz.) Females are less aggressive and easier to introduce new rats to, and generally get along well with each other if properly introduced. Females do not smell if properly taken care of. Females have softer hair. Females continue to remain very playful, frisky, and active as adults. Females generally are not ones for being held and loved on for very long. Females love to play games. Females tend to chew on things more, cause more mischief, and get into more trouble. Females are very prone to getting one or more benign mammary tumors within their lifespan. These tumors can grow extremely large and should be removed for the sake of the animal. Spaying your female at the age of three months can greatly reduce/remove the risk of them developing these tumors, along with providing many other health benefits. (See "Should I Spay/Neuter my Rat?" located in this Guidebook to learn more about this subject.)     The female rat. Miscellaneous... If you would like rats for your children or are looking for a lap rat, adopt males. If you want to be entertained and enjoy playing games with your animal companions, adopt females. Both sexes are playful and active as youngsters. Do not adopt males and females together, unless you plan on fixing either the males, or the females first before putting them in with one another. Otherwise you will end up with tons of baby rats. Generally, through research, we have found that having males and females within the same house may cause more fighting than normal. Unless it is only a single male by itself. Males become much more macho with a female around. So if there are two or more males with females present, their hormones will be elevated and they might fight more frequently with each other. Neutering them would greatly decrease this behavior. (See "Should I Spay/Neuter my Rat?" located in this Guidebook to learn more about this subject.) Be wary when adopting females! Make sure that whoever it is your adopting them from, has separated their baby male and female rats by the age of five weeks. Otherwise your new girls could be pregnant! This is something you don't want to deal with. We strongly suggest getting your girls from somewhere else if you find that they were not separated. WARNING! These are general guidelines. These are not hard and fast rules. There are always exceptions. You could have a very tiny male, or a very aggressive female, or a male that loves to play, and a female lap rat. Rats are all individuals in spirit and body. Generally though, the above information remains true.