Freshly Hatched Black Coot Chicks
You probably do not have spikey orange hair, and even if you did, it is unlikely that your parents would show the enthusiasm for it as do the parents of Black coot chicks. Their young sport the equivalent of punk gear – but not to attract other punks or to get photographed. Rather, the chicks wear this garb to compete with their brothers and sisters for parental attention.
Adult coots are sooty black birds somewhat smaller than a duck, and inhabit streams and lake shores. Coot chicks, however, emerge from their shells with bright orange plumes around their necks and shoulders that stand out sharply against their darker natal down. These plumes make the chicks more conspicuous to predators and so represent a risky choice of attire for an already vulnerable creature.
Recently, a team of Canadian researchers, reporting in the science journal Nature, uncovered the reason for this risky choice of plumage. The chicks’ lives depend upon it: Black coot parents have favourites among their chicks and feed them more. These favourites are those chicks that produce the bright orange plumage.
Why do coot parents have such eccentric tastes? One possibility that will seem all too familiar to human parents is that it is the parents that must put up with the chicks’ tastes, not the other way around. Coot chicks gradually lose their orange plumage as they progress towards fledging, which occurs at about three weeks. Feeding a chick more may hasten the day it fledges and thereby reduce the risk of its being preyed upon.
The chicks may be employing their bright plumage as a form of blackmail, to get their parents to feed them. Their strategy mimics that of the child who holds its breath to get its parents’ attention. The difference, of course, is that holding one’s breath is generally self-correcting (but try telling a parent), while playing with one’s life to blackmail parents may not be: the first chick to attempt this was likely whisked off by a predator. Blackmail as a strategy, if it ever evolved, probably quickly died out.
A more plausible reason is that Black coots, like many bird species, practise bet-hedging: they lay more eggs than they normally can bring up. In a bountiful year, the payoff to laying a large clutch of eggs is high: the parents produce many young, thereby banking lots of Darwinian currency. But because eggs themselves are not so costly for parents to produce, losing a few in bad years is, in theory, more than compensated by the occasional good year. Thus, to keep up with their neighbours in the reproductive stakes, coots are forced regularly to confront something of an avian Sophie’s Choice.
This in turn has profound implications for the chicks. Six is a common clutch size, but the chosen few may number only two or three. At the expense of their siblings, chicks must actively convince their parents that they should not be among the dispossessed. Thus life for young coots unfolds in a ruthlessly Hobbesian state of Nature, in which brother and sister fight each other to inherit the rights to the next generation.