Mateless in Hawaii

             Albatross are almost synonymous with monogamy in the bird world, they are the poster child for long term breeding pairs and obligate dual parenting of chicks. Both genders also happen to look the exact same. So it came as a bit of a surprise to some researchers when they went out and decided to genetically sex a population of Laysan Albatross and discovered that there was a serious gender skew on the island, and even MORE shock when the realized what exactly that gender skew had wrought in terms of social behaviors. 

            I’m talking about the population of Laysan Albatross on Oahu Island in Hawaii that is 59% female, of which 31% of the breeding pairs are female-female. This is big, and the reason this is big is because every single female-female “breeding” pair were completely unrelated to one another.

            Cooparative breeding does occur in nature, wherein others of the species pitch in to help rear offspring which are not directly their own. However, in essentially every case of this type of behavior the offspring being reared or the parents being helped were in some way related to the helpers. But that is not the case on Oahu!

            Monogamy SHATTERED right?! Wrong. It turns out that in this male-barren land the unpaired females have managed to get the monogamous male albatross to have extra-pair copulations (Okay, monogamy a little bit shattered) in order to breed themselves. In one study done on the success of the female pairs it was noted that almost half the female-female pairs were together for the full 4 years of the study’s duration (Young, Zaun & VanderWerf 2008). They even found from another researcher that one pair of ladies had been together for a full 19 years, indicating that they chose the homosexual rearing strategy over the traditional one.  

Female-Female breeding pair of Laysan Albatross

 

 

            While the female-female pairs had less success in hatching the eggs than the male-female pairs, of the chicks that hatched the survival rate was essentially equal. Those pairs staying together for more than one year had at least one offspring from each parent hatch and fledge. That alone means that both females agreed to this continued cooperation. A sort of you hatch my egg I’ll hatch yours system that is essentially based upon a mutual agreement. 

            All in all, these same-sex pairs of Albatross have adapted to their new “environment” by recognizing that some reproductive success with another female is better than NO reproductive success by not breeding at all. It was decided by Young et al that while the Albatross’ social behavior has shifted to include same sex pairs, they are still operating under their monogamous instinct. Which is working for them. It also goes to show how dramatically gender ratios can affect the behavior and reproductive strategies of a species in a relatively short amount of time. 

Personal hypothesis as to why there are so few male albatross on Oahu.

 

References

Young, LC, Zaun, BJ & VanderWerf, EA 2008, ‘Successful same-sex pairing in Laysan albatross’, Biology Letters, vol. 4, no. 4, pp. 323–325.

Pictures:

http://esciencenews.com/articles/2009/06/16/same.sex.behavior.seen.nearly.all.animals.review.finds

http://www.timdrussell.com/pythonstills.htm