Thursday, September 15, 2005

More Penguin Family Values

During my last discussion of how the Emperor Penguins (the species, not to be confused with Emp. Peng.) are being held up as paragons of conservative family values, you may have been asking yourself, "Just what is the divorce rate among penguins?"

One of our many mottoes here at Penguin Perspectives is, "You have a question; we have an answer." While we usually do not guarantee that the answer provided will match the question, in this case it does. Someone actually did a study on the divorce rates of aptenodytes--that would be the King and Emperor penguins--and no, you did not have to pay for it. It appears to have been sponsored by a couple of French research agencies. Man, those French like their penguins.

Turns out that the vaunted emperor penguin has a year-to-year mate retention rate of 15%. The study did not show any penguin couples retaining the same mates for longer than 4 consecutive breeding seasons. In sum, emperor penguin divorce rate after 1 year: 85%. Penguin divorce rate after 4 years: 100%. Makes humans look downright good at 50% (I cite that with the usual disclaimer that I disagree with the methodology by which that figure is arrived at).

Interestingly, the study also indicates this isn't just because one penguin in the pair is late back to the rookery site, so the other takes on another mate on the assumption that the last year's mate has been eaten or is otherwise not coming back. In 19 cases where penguins did not renew pair bonds and the researchers knew the arrival dates for both birds, in only 7 cases the first-arrived bird already had a new mate when the old one arrived. In 12 cases, the first-arrived bird knew that last year's mate was there, but still opted for a different mate.

1 comment:

Janet said...

In the discussion of how many emperor penguins retain their mates, I forgot to mention that penguins have a reproductive span of about 16 years. Thus, keeping a mate for 4 breeding seasons means they stick together for about a quarter of their available years, or the equivalent of a 15-year marriage for humans.