two or more females combine their litters in a single nest and raise them together. The mothers may be related or unrelated, and the litters may be the same or different ages. Often includes communal [..]

Informal, illustrated definitions of rat behavior terms

Allogroom

  Grooming consists of rapid little nibbles, in one spot or moving slowly to one side.  Slow motion video analysis reveals that the groomer seizes folds of neck skin between his teeth (Miczek and Boer [..]

Excessive grooming in which the fur is nibbled off. Rats may barber each other

is also found in non-lactating rats, in which case the rat may nibble off fur from its forearms and chest. Barbering is sometimes caused by Demodex

Phase of the female rat's ovarian cycle during which she displays reproductive behavior. Behavioral estrus corresponds to vaginal proesturs, the 12 hour period before ovulation.

, the female solicits

One rat grooms a recumbent rat's belly. May be an attempt to reach the nape, which is the goal of play fighting. See also "Belly-up roll

Juvenile-type defense tactic in which one rat rolls onto his back before another, sometimes after receiving a nip or bite on the rump. The top rat may then step on the supine rat, sometimes orienting [..]