Cows: when in groups, cows will form a preference for and strong bonds with another cow, equivalent to a human having a best friend. Their heart rates and stress levels lower when they are near their bestie and they often communicate their affection with licks.
Pigs: Like people, they are happier and healthier when they have good, stable friendships and time to socialize with other pigs. Pigs also mourn the passing of their companions.
African grey parrots: These birds are monogamous for life, and both parents look after chicks and are seen grooming and feeding chicks. The father feeds the mother while she is incubating the eggs.