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Why Do Barn Owls Divorce?

Love is a fickle thing—even in barn owlsThese normally monogamous birds sometimes call it quits and move on to new partners—nearly a quarter of the time, in fact, says a new study published April 28 in the Journal of Evolutionary BiologyAmong people in the U.S., the divorce rate is about 40 percent.

And while these “divorces” may mean sacrificing quality for quantity, both sexes can benefit from the split.

Photo of a barn owl in flight.
A barn owl flies in Norfolk, England. Photograph by Sarah Darnell, Science Faction/Corbis

On a faithful note, barn owls tend to divorce only when breeding isn’t going well—for example, if there are only a few eggs laid or not many surviving chicks. When a pair is making a lot of babies, the birds remain quite loyal—and that chick-making relationship only gets better with time because the two mate more often, potentially maximizing the size of the family long-term.

Sometimes, It’s Splitsville 

Amélie N. Dreiss and Alexandre Roulin, of the University of Lausanne, Switzerland, studied a population of free-living barn owls in western Switzerland for 24 years, observing how the pairs bonded and how many babies they had.

Barn owls are productive parents, often laying two broods per year with up to 11 (an average of six) eggs per brood. (Take National Geographic’s backyard bird quiz.)

But if there’s a year where they don’t have many babies, either partner might choose to seek a new mate.

Among the 634 owl pairs studied, 23.5 percent divorced: 166 pairs stayed together and 51 split, with males tending to “get the house,” meaning they stayed at the original breeding site.

Most in the divorce group had given the relationship just one year before separating (only a small percentage stayed faithful for multiple years—one couple really gave it a go, staying together for six years before giving up).

Who Leaves Whom?

In this species, very few animals “cheat”—so getting divorced is the only way to switch partners.

Because the birds are nocturnal and much happens after dark, it’s hard to know for sure which sex more often initiates the split, the scientists say. (Watch a video of night owls.)

Females tend to leave the nest after divorce, though some might be pushed out rather than choosing to go. What is known is that younger males are more likely to divorce than older ones are.

Roulin says that’s not because young males aren’t ready for commitment, but rather “it takes time to find the best mate.”

“A male may not have other choice than to divorce when he is young” in order to secure the most suitable sexual partner.

Looks Aren’t Everything

As for choosing partners, male barn owls prefer females with more and larger black spots on the tips of their feathers, though why exactly that’s considered better is unknown.

But after divorcing, the separated males often pair up with a younger, “lower-quality” bird (one with less black coloration)—suggesting that their reason for divorce isn’t to find a “superior” partner. (Also see “Wild Romance: Weird Animal Courtship and Mating Rituals.”)

“The cost of divorce for males, then, is to repair with a less sexy female,” Roulin says.

In this species, then, compatibility matters more than good looks. Males were typically better sexually matched with the new bird, so that breeding produced more chicks. Same went for females (who, unlike males, didn’t lower their standards when seeking a second partner): They usually fledged more chicks with a new mate than they had with the old.

Tight Families Thrive

Though divorce has its reasons in barn owls, the study authors note that chick survival was highest of all in families in which the parents were long-term, committed partners.

So if it takes a few tries and a few broken hearts, the goal is to find a truly compatible mate and then make babies, hanging in there for the duration. Not unlike the goal of another species we know.

Follow Jennifer Holland on Twitter.

Comments

  1. Tom Sweetnam
    Colorado Remote
    July 19, 10:57 pm

    Does anyone know a good barn owl divorce lawyer in Southern Colorado? We had a firm here, Hootie, Sneaky, & Mousie, but with the drought and all, they moved their firm up to metro Denver.

  2. Dumb guy
    Your moms house
    May 22, 12:39 pm

    Owls are birds that like fish…. :-) fun fact

  3. Jasmine Syedda
    May 1, 10:27 pm

    That was a very interesting article! And nice poem!

  4. Mark Pommier
    United States
    May 1, 12:41 pm

    Fascinating, and thanks to the diligent study of these birds over such a long time period!

  5. Jennifer Holland
    May 1, 10:46 am

    Great details on what the owl’s spots reveal…thanks to Megan for those links.

  6. Justin
    Walt's Woods
    April 30, 9:43 pm

    Like the poem Ima

  7. Megan
    April 30, 5:49 pm

    Spots on barn owl plumage relate to resistance to parasites and developmental homeostasis for a female’s offspring:

    http://rspb.royalsocietypublishing.org/content/270/1511/167.short

    as well as to parental investment and corticosterone levels on the part of the male:

    http://www.sciencedirect.com/science/article/pii/S0018506X08000780.

  8. Jennifer Holland
    April 30, 5:32 pm

    Wow, we have a poet among the owl-philes!

  9. Ima Ryma
    April 30, 4:58 pm

    It was a May/December match.
    I was December. He was May.
    Though a bit gray, I was a catch
    In a sexy maternal way.
    Lady of the evening – yes,
    I tried for sake of family.
    But he came to me less and less.
    I knew he wanted to trade me
    In for a newer model, plus
    He would get the love nest – no yarn.
    Though humans do it more than us,
    Barn owls do break up in the barn.

    Instinctively, I knew of course,
    My mate had chosen to divorce.

  10. Monika
    Georgia,Cedartown
    April 30, 11:19 am

    Very interesting to read about.c

  11. Monika
    Georgia,Cedartown
    April 30, 11:18 am

    Very interesting to read aboutu