Sunday, September 26, 2010

The Red Beak District


Forget 'Fort St' in Auckland or 'Kings Cross' in Sydney, there are far more sinister districts popping up all over the place at this time of year. From August to March every year New Zealand's recreational parks and open fields are transformed into 'Red beak districts' where promiscuity and 'fowl play' is the name of the game!

Pukekos (Porphyrio porphyrio) would have to be the hippies of the avian world, a world that consists of 'free love' and communal living! Group sex, partner sharing, homosexuality and incest are a common occurrence. In fact, in the pukeko world you could say that love is one big 'family affair'.  (Right: No privacy in a pukeko commune)

Pukeko's have a complex social system, and monogamy, polygamy, polyandry,  and polygynandry can occur  within the same population! Females are often hounded by numerous males and can be copulated by up to three different males within a matter of minutes! (Below:  Males hastily pursue an unwilling female)

This kind of libertine lifestyle raises a lot of questions... how could this level of promiscuity benefit the pukeko? Partner sharing seems to go against the evolutionary grain, where it is argued that as a result of natural selection individuals will try and maximize their own genotype in subsequent generations. Although in communal breeding groups it seems that they toss their own interests aside in order to assist the reproductive efforts of others and benefit the group as a whole.

There are many theories as to why these purple clad hippies share mates and participate in incestuous and homosexual activity when it seems detrimental and pointless to their evolutionary success.

When it comes to inbreeding it seems that pukeko have several mechanisms for reducing the disadvantages of incest such as possible gamete selection (the process of determining which egg matures and what sperm succeeds in fertilizing the egg). Other theories suggest that regular inbreeding may have eliminated deleterious generic consequences. Whatever the reason or reasons may be, there have been no obvious harmful effects due to inbreeding observed in pukeko breeding groups. Homosexuality and partner sharing are believed to help synchronize sexual cycles allowing several females to lay in the same nest at the same time.

Although these raunchy rails' sexual habits may seem a little lewd and communal breeding an evolutionary paradox, these districts, believe it or not, are 'family friendly'. In fact these lewd acts seem to benefit the group as a whole, and strengthen family ties. Community breeding offers its fair share of advantages, such as safety in numbers as each 'commune' has several males to defend it. It certainly makes the jobs of nestbuilding (Below), chick feeding/care (Right) and incubation (which is shared by all adults within a group) a bit easier with more helpers around. Due to the fact that males and females mate freely within the group, males have an uncertainty about which chicks they've fathered and this probably ensures that they  stick around and help with the raising of the chicks.

Each female will lay up to 7 eggs, and a communal nest can have eggs from 2-3 females. Unaware of the pukekos communal nesting behaviour early ornithologists were fooled into thinking that some females were highly productive because their nests contained up to 20 eggs. With multiple chick minders each chick may be looked after  by a parent, aunt/uncle or an older brother/sister.

Left: Males and females both participate in nest building, and in communal breeding groups helpers also lend a hand (or a beak).


Right: allopreening. In pukekos, allofeeding and allopreening (where birds will feed and preen one another) is a form of courtship and occurs between all sexually active birds in a group. Male pukeko also hold water weeds in their bill and bow to the female with loud chuckles as a form of courtship. 


Left: A pukeko swimming. Although not web-footed, pukekos are surprisingly strong swimmers.

Below: A pukeko nest  situated in an open field.

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