Animals are not normally known for exercising restraint when it comes to reproduction. But for all the attention paid to the promiscuity of busy breeders like dogs and jackrabbits, some critters display a different side of animal nature by sticking with one sexual partner for the duration of their lives. Here are six such creatures who know a thing or two about monogamy.
Although Benjamin Franklin once disparaged (possibly in jest) the bald eagle's "bad moral character," America's national bird upholds a high standard for family life by (mostly) remaining faithful. Following a kamikaze courtship ritual in which two birds lock talons and tumble end-over-end until they nearly hit the ground, the male and female settle into a period of domestic bliss marked by dad's willingness to undertake incubation and feeding duties. The "divorce" rate for these birds is less than 5%, according to scientists. And while they spend large chunks of the year alone, bald eagles mark their fidelity with a shared long-term commitment to nest building: One such home put together by an eagle couple in Florida was found to measure 9.5 feet long and 20 feet deep. It holds the record for the largest bird's nest ever documented.
Also known as sleepy lizards or two-headed lizards, shingleback pairs are a common sight on the back roads of southern Australia. As with bald eagles, these bulky reptiles largely prefer to remain alone, until reuniting with the same partner for the mating season. Unlike those raptors, however, shinglebacks share virtually no child-rearing duties (there aren’t any — the offspring quickly strike out on their own), so it's unclear what draws the same couples back to one another. One theory suggests that it’s simply a matter of safety with these slow-moving animals, who trust their partners to be on the lookout while they fill their bellies.
Unlike some of their human counterparts who enjoy "playing the field" amid the social opportunities of big-city life, urban-dwelling coyotes have demonstrated that they'll stick with one mate for the long haul. This likely has to do with the large litters birthed by females, who need help feeding and caring for the young'uns. It also explains why coyotes are known to be unusually aggressive during and after the winter breeding season; as devoted family animals, the males are simply doing their best to divert danger from the dens of their vulnerable partners and pups.
Although the lives of prairie voles can end after a few months in the unforgiving wild, these North American rodents make the most of their brief time on Earth by forming powerful connections with a mate. This attachment becomes even more pronounced in captivity, with voles showing signs of empathizing with a stressed partner or grieving after the partner’s death. Thanks to decades of research, scientists have a good idea about the hormones that fuel such strong animal bonds, and even use them as clues to help decipher the ongoing mystery of human relationships.
Fish in general aren't wired toward mating for life, but certain species of seahorse, including the White's or Sydney seahorse (Hippocampus whitei) in Australia, are known to engage in such behavior. This can be explained by factors such as a shrinking population and poor swimming capabilities, which make finding another mate difficult, as well as the quirk of nature that thrusts the burden of seahorse pregnancy on males. While the guys are tied up in a gestation process lasting from two to four weeks, female seahorses continuously prepare another round of eggs for insertion, ensuring the propagation of the species with an invested partner.
The third-largest penguin species, gentoos are best known for a distinct mode of courtship in which the male presents the female with a pebble. If accepted, the pebble marks both a symbolic gesture of a lifelong relationship and a practical tool for family building, as pebble nests serve to keep eggs and hatchlings off the cold ground. As with many other would-be monogamous animals, gentoo penguins are known to occasionally stray from their long-term mates, particularly in the controlled, predator-free environs of captivity. Regardless, the penguins almost always return to the same nesting site, suggesting that maybe it’s all about the pebbles, after all.