Do rats mourn their dead?

Rats do not mourn their dead in the human sense of understanding death and feeling grief, but they do show social behaviors that can look like mourning or distress when a companion dies. Rats are highly social, intelligent animals that form strong bonds with cagemates and colony members, and they can show changes in behavior when a familiar rat disappears or dies, such as becoming less active, eating less, searching for the missing rat, increased vocalizations, and showing signs of stress like over-grooming. Laboratory studies have shown that rats display empathy-like behaviors, for example they will try to free a trapped cagemate and will share food, and they show physiological stress responses when witnessing another rat in distress. When a rat encounters a dead cagemate, it may sniff, nudge, and groom the body, and may avoid the area where the death occurred for a time, possibly due to smell or association with danger rather than understanding of death. Wild rats may also avoid traps that have killed other rats, suggesting they associate the location with danger. So while they likely do not have a conceptual understanding of death as humans do, they do experience social loss and stress when a bonded companion is gone, which is why pet rat owners are advised to give extra attention and consider companionship after a rat dies.