What Types of Birds Mate for Life? - Birds and Blooms

What Types of Birds Mate for Life?
While there are monogamous birds out there, bird mating habits vary by species. Learn which birds mate for life, and which move on.
Courtesy Tonya SharpBald eagle pairs mate for life
When it comes to love and marriage, bird mating habits aren’t much different than people. Birds meet and then carry on a courtship that includes dinner dates, dancing and just hanging out together. Birds, especially males, sing, show off a lot and wear flashy adornments just to impress females. Then if the two birds like each other, they become a pair, build a nest, raise youngsters, school them and send them off to form their own families. Also like people, pairs are not always faithful and will have flings with individuals other than their own mates. If the marriage doesn’t result in raising young, the pair may “divorce”, remarry and try again. Discover the monogamous birds that mate for life.
Birds That Mate for Life
It’s fairly rare to find monogamous birds that remain together “until death do us part,” a fact not realized until pretty recently. Until the development of DNA fingerprinting techniques in the 1980s, most people thought birds faithfully mated for life, or at least for the season. Using DNA, scientists have produced some shocking discoveries. Most birds are far from monogamous.
Most birds do not mate for life, and most of those that do aren’t quite as faithful as we’d like to think. Over 92 percent of all bird species form a pair bond and stay together for at least part of the nesting cycle. Yet DNA tests of baby birds have shown that in over 75 percent of these species, some birds have mated with one or more birds other than their “social mate.”
Monogamous Birds
Yet, there are a few species of birds that meet, court and form pair bonds that result in many offspring, year after year, until one of the pair dies. For nearly all swans, geese, ducks, cranes, storks and a few others, long-term monogamy is the preferred relationship. Even though these birds are quite loyal, few demonstrate the fidelity of the Bewick’s swan, a European native. At the Wildfowl Trust in Slimbridge, England, swans have been studied for more than 50 years. In all that time, the researchers haven’t found a single case of “divorce” among the thousands of Bewick’s swan pairs that have successfully raised young.
We can assume that our native tundra and trumpeter swans are much the same. Wild swans probably survive an average of 12 years, with records of them reaching 26 years of age. When one member of the pair dies, the widow or widower might eventually take a new mate, but they don’t rush into it, often taking a couple of years to find an acceptable partner. Some don’t remarry for up to 6 years after the death of a spouse.
Bald eagles mate for life, but possibly only because they can’t work out a property settlement. Eagles don’t stay together over winter, preferring separate vacations. The pair returns to the same nest each year, which can grow almost 9 feet wide. However, if one or the other doesn’t come back, the remaining bird readily accepts a new mate at the nest.
Among our favorite pairs, northern cardinals appear to have a longer-lasting marriage than most songbirds. During winter, the two are not very nice to each other, but come spring, the male’s fancy takes a new direction. Instead of chasing the female away from the bird feeder, as he did all winter, he offers her a sunflower seed and the courtship starts again. Whether they are the same male and female as last spring, we can’t be sure, but most of us would like to think so. After all, it’s nice to have the ending, “and they lived happily ever after.”
George Harrison is an expert about feeding and attracting birds and avian behavior. He studied birds all over the world and is an award-winning photographer and author. He formerly served as managing editor of National Wildlife and was a longtime contributor to Birds & Blooms.