All penguins except emperors mate for life. Gentoo penguins have complicated courtship rituals where the male looks for the appropriate rock to give to his mate.
Penguins
Beavers have lifetime relationships. Two-year-old dam-builders mate. Mated pairs raise offspring in colonies. Each year, a beaver pair has 1-4 babies.
Beavers
All 9 species form pair connections at 10 months. Even if they're good for beginners, it's cruel to isolate them. Gregarious and social, yet happier in pairs.
Lovebirds
Sandhill cranes mate for life. Once wedded, these enigmatic birds stay together until one dies. The survivor will then seek a new partner.
Sandhill Cranes
Lifelong mates are American eagles. At 4 to 6 years old, bald eagles pair together. Bald eagles are monogamous until one dies.
Bald eagles
Roofing lizards are monogamous. Male shingleback lizards fight to mate. If he wins and she accepts him, they'll be together forever.
Shingleback lizards
Romantic swans. White feathers and monogamy led to their introduction in the 19th and 20th centuries. These birds pair at 2-3 years old and reproduce once a year.
Swans
While coyotes are blamed for killing pets during breeding season, they are loving parents and pair for life. At age 2, coyotes reach sexual maturity and choose partners.
Coyotes
Northern cardinals are classic North American backyard birds. Lifelong monogamists, cardinals. Some pairs are monogamous for a year then find new mates.