National Geographic

Same-Sex Mothers: Letting Albatrosses Be Albatrosses

There was a time when the Laysan albatross might seem a perfect icon for the virtues of marriage. When naturalists visited the bird’s nesting grounds in the Pacific, they’d find males and females bonded in pairs for life. Each breeding season the pairs of birds would nuzzle their heads together and perform other adorable courtship rituals. After they mated, the female would lay an egg. Both the male and female would take turns sitting on the nest to incubate it, taking three week shifts. After the chick hatched they’d rear it together until the end of the breeding season. The birds would then fly out to sea in different directions, but they’d return the following year and start up their partnerships all over again. The albatrosses would repeat this behavior for life–which, in their case, can last for many decades.

But then scientists realized they weren’t seeing the birds correctly. It turned out that sometimes a pair of albatrosses were both females. On the Hawaiian island of Oahu, for example, 31 percent of the pairs are same sex couples.

Two female Laysan albatrosses. Photo by Eric VanderWerf

Two female Laysan albatrosses. Photo by Eric VanderWerf

Lindsay Young, a biologist who has been conducting a study on Laysan albatrosses for a decade, bristles when people try to use her research as a weapon in cultural debates. “‘Lesbian’ is a human term,'” she told the writer Jon Mooalem, who wrote a wonderful feature about same-sex animal couples for the New York Times Magazine in 2010. “The study is about albatross. The study is not about humans.”

I was reminded of Young’s words when I read her latest report on the birds, which appears today in the Proceedings of the Royal Society. Young and her colleague Eric VanderWerf analyzed ten years of field notes for every female Laysan albatross on Oahu–all 145 of them. In that data, they searched for an evolutionary explanation for why so many of the birds are in same-sex pairings. The answer they’ve reached is an intricate one–and it hinges on what it means to be an albatross, not a human.

Over the course of the study–from 2003 to 2012–Young and VanderWerf observed a number of same-sex pairs sticking together for years. Each breeding season, the females would find male albatrosses to mate with. Then they’d return to their own nest to lay their eggs. Like male-female pairs of albatrosses, they would take three-week shifts. But a pair of albatrosses can only incubate a single egg, and so when both females laid one, one of their eggs died. From year to year, it appears, the females alternate between which bird gets to lay an egg.

From an evolutionary point of view, Yong and VanderWerf found, the numbers are bleak for a female albatross with a female partner. At best, she’ll get to lay one egg every two years. That’s half the maximum rate that a female with a male partner can hope for. In the real world, however, all the birds fall far short of their upper limit. For one thing, albatrosses sometimes skip a breeding season. For another, many albatross chicks die in their first year.

But same-sex pairs have worse luck than male-female pairs, Young and VanderWerf’s research shows. An average female with a same-sex partner produces 80 percent fewer chicks a given year than one with a male partner. Over the ten years of the study, a female in a same-sex pair ended up with just one offspring on average. Her counterpart in a male-female pair ended up with 2.14 of them.

Two female albatrosses. Photo by Lindsay Young

Two female albatrosses. Photo by Lindsay Young

There may be many reasons that same-sex albatrosses have fewer offspring. One may be that the females themselves are at a greater risk of dying. Young and VanderWerf point out that males take over the first three weeks of sitting on the nest after a female lays an egg. In same-sex pairs, the female that lays the egg goes straight into an incubation shift. Unable to return to sea to find food, she starves for three weeks and puts her health at risk.

Young and VanderWerf’s study is impressive for having stretched across a decade, but that’s just a small fraction of the fifty years during which a Laysan albatross can lay eggs. The differences that Young and VanderWerf have documented between same-sex and mixed sex pairs probably expand drastically over the entire lifetime of the birds.

The scientists also found that the albatrosses weren’t completely locked into their relationships. At the start of each new breeding season, a few females switched from a male partner to a female one. Likewise, females abandoned female partners for males. These switches illustrate just how much better male-female pairs do than same-sex ones. When a female bird switches from a female to a male partner, her productivity doubles.

What’s also striking about these switches is that they are far from random. Females that fail to produce a chick are three times more likely to end up with another female the next year than females that succeed.

Young and VanderWerf also found that females are much more likely to switch from females to males than from males to females. But they only switched to males if they had a successful breeding season the year before. Not a single female albatross that failed to reproduce one year went on to switch to a male partner the next year. (The full complexity of a female albatrosses’s life is mapped out in the figure at the bottom of this post.)

Young and VanderWerf sketch out an explanation for all of these different patterns–same-sex pairs included–that starts with one of the most important facts about albatrosses: they’re sharing the ocean with us.

Laysan albatrosses soar across the ocean for fish. Female and male albatrosses go their separate ways to go fishing, and the males appear to be more likely to go after the bait set out by long-line fishing boats. The deaths of male albatrosses may account for the fact that, at some albatross colonies, the majority of birds are females. At the site on Oahu where Young and VanderWerf do their research, for example, 60 percent of the birds are females.

In these places, there simply aren’t enough males to go around. A female will have her highest possible reproductive success if she can find a male partner, but there’s a fair chance that she won’t. If she can find a female partner, on the other hand, she may only be able to produce one chick in a decade. That’s pretty paltry compared to females with male partners. But it’s infinitely better than the zero chicks a female albatross will produce if she has no partner at all.

This scenario can also account for the behavior of the males. In many species, males compete intensely with each other for the chance to mate with females. They may also put on an elaborate courtship to gain a female’s favor. The females can then choose which males they will mate with. But this arrangement evolves because ┬áthe females invest a lot of time rearing their young. At any moment in these species, there are a lot of available males and relatively few females.

Among the Layson albatrosses on Oahu, the situation is flipped. There are many females and relatively few males. The fact that females only switch to males after a successful year may be the result of males choosing among many potential mates. They’re keeping an eye on other albatrosses, and they prefer fertile females. The males also take advantage of the abundance of females by serving as sperm donors. By mating with same-sex female birds, they can have several offspring, while only putting in the effort to raise one chick.

From left to right: soda can, albatross egg, and chicken egg. From Albatrosses at Work: www.wfu.edu/biology/albatross/atwork/atwork.htm

From left to right: soda can, albatross egg, and chicken egg. From Albatrosses at Work: www.wfu.edu/biology/albatross/atwork/atwork.htm

For albatrosses, same-sex partnerships aren’t a genetically hardwired adaptation implanted in the brains of a minority of birds. Instead, they’re just one part of a flexible set of behaviors that the birds can switch between to make the best of the situation they find themselves in.

What does any of this mean for same-sex marriage laws? I’ll only answer that question if you lay an egg the size of a soda can first.

Probabilities of different transitions in the life of a female Laysan albatross. From Young and VanderWerf

Probabilities of different transitions in the life of a female Laysan albatross. From Young and VanderWerf

There are 10 Comments. Add Yours.

  1. rosa Sparovich
    November 30, 2013

    Does that mean the female albatross have sex with each other or they are just companions. There is a big difference. My grandmother and her friend Paula were both widows and knew each other since they were children. Later in life they decided to live together so they have each other company but they didn’t have sexual companionship. People can live together but doesn’t mean they are having sex!!! Some couples who have been married before to each other decide to divorce from each other but for different reasons beside sex decide to continue living in the same house and she will take care of his clothes, food , clean house etc. and he will pay the bills etc. but they dont have to have sex to each other!!!

  2. teknicol
    December 1, 2013

    If all lesbian women mated with the cream of our male population, and reared their offspring together the decline in our hereditary genetics may be halted. What’s wrong with having a few more ‘Nobel Prize Winners’ offspring’s around?

  3. Nelson K Akpese
    December 1, 2013

    Female and female cannot make sex to Reproduce. They are Females of the same sex but different IDENTITY of Sex. Humans should have been reproduce if not of Sex of Adam and Eve in reproduce for Research the made or did to Reproduce. Not Satan. Satan does not do or doing so he is not BLAMED of FAULT but DECEIT AND GAIN TO WIN GOD’S KINGDOM AND DO AND DOING. Satan ALLOWED the research that is why it went on. It is biological Research to reproduce.. But REPRODUCE is not of Sex but sex of fault to REPRODUCE. God would have been giving HUMNS childeren in REPRODUCE. So he could or Chief or CHIEF of ANIMALS could give also. Animals are plain without fault so God can do or ANIMAL CHIEF do and give the Children FREE. So hunans good[could be given children.} So in Nature that you are being natured by nature or God you can be be given children by god or Nature. Nature is God. God did things that could be used to NATURE Humans and things living for or for him and it. You are using natures things so you are in Process of being made with it as allowed in theory to with it and get to Natutre form, God. Something done in a way to gain of a PROCESS is of the Process made. So you use Nature’s thing and so you are in Process of being Natured.. Things to nature are of nature, God. So there is God. In the bible you are being natured by God; so is God that do, Naturing. So Animals or living thing or Birds of the SAME SEX can produce without Sex but being given. So is Human. Human Beings were brought forth after Creation of Adam and Eve by sons and daughters of god which were Living by then and were Spirits. that is generation and Adam and Eve’s research produce generate which were Israelites in the Bible except mariage difference. You present people were brought forth by Ghosts or people of your type[before birth people type] Scientific[NOT IN THE BIBLE} You are in God's generation but not in the bible unless you follow him or in process to Heaven or go to Heaven before your identity will be found there. it is not Spiritual Omen{magical to think] but proof to fit to Heaven. You are Scientific but not to heaven. You are people of Generation of your Own.
    The bring the Produce of children of birds or the birds too them to mate. They are their people can make. They make the m have the eggs as your Research is of produce of kids or laying eggs [hens in farms] and so{like put something in mouth and lay[as dne in magic but leaf or known thing they know or look or looking. Actually is looking to god for but excersice to do. Humans can do but don’t. Gay is not allowed

    [CZ: Noted without comment.]

  4. Nelson K.Akpese
    December 1, 2013

    ADD
    2.Nature has verb so you are being natutred. So there should be nature to do; or do it
    Nature has verb and can do so there is nature to do and made of Noun nature and that is god Quality in Bible.
    God definition fits nature I talk

  5. Ella-Vee Hoefling
    December 2, 2013

    Forget sexuality and spirituality in this article, the data is in regards to birds, not human beings! The article seems to indicate that this behavior is more likely to an arrangement to rear offspring where there are a disproportionate number of females to males.

  6. Malcolm
    December 5, 2013

    “[CZ: Noted without comment.]” <— BEST comment of the day hahahaha!

    By the way it's amazing how these birds figure when to pick a female or male partner to maximize their reproduction output. The number is till pretty low though, only 2.14.

  7. Johan
    December 6, 2013

    Only 2.14 offspring per decade. These birds reproduce over more then four decades. That makes nine kids per couple.

  8. Ida Jablanovec
    January 12, 2014

    Who paid for this study?

  9. Julia Burnstein
    January 15, 2014

    Why do you assume that the only value/goal of female albatrosses is the production of offspring? Perhaps the lesbian nesting albatrosses are contributing positively to their communities in other ways.

  10. wyndyla
    June 28, 2014

    I’m surprised that there is no mention of “companionship” as a choice for female partnering. It is common in other species–cats, dogs. ho hum….

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