I hit Shouldice Road early in the morning to look for Sandhill Cranes (though they are uncommon breeders in this area, a pair regularly nests in North Dumfries).  Quiet, unpaved country roads are becoming less and less common these days.  I could hear the Sandhills calling when I arrived, but as they were quite distant and not in sight I took my scope down to the marsh instead.  A pair of Common Moorhens were foraging in the reeds, busy feeding their brood of three.

Moorhen chicks, with their balding pink heads, aren’t what most people would call cute, but their bare scalps and colourful red and blue skin patches evolved to charm their stern and overtaxed parents.  Like many other members of the Rail family, Moorhens frequently punish their chicks by ‘tousling’ — grabbing them by the head and giving them a quick and violent shake.  It’s quite distressing to the chicks, who may become so traumatized by this abuse that they cease to beg for food altogether and starve to death.

It seems bizarre and cruel, but there’s a good reason for it.  Food availability cannot be predicted at the time the parent birds begin laying, and so, like many birds, Moorhens will hatch more chicks than they can take care of on the off chance that food will be especially abundant that year.  When the hungry brood arrives, the parents are now faced with a dilemma — feed all chicks equally and possibly lose most of them to starvation or overcompensating sibling rivalry, or do their best to curb sibling aggression and focus their attention on the strongest chicks.  Tousling punishes those chicks who beg too forcefully, and the intensity of their skin colouration may help the parents to gauge which of their offspring is the hungriest (much like the gapes of songbirds).