Coots Can Count
(This column was first published in the April 28, 2003 issue of The Buffalo News.)
"Stupid as a coot" -- you may have heard an expression like that. If you have, I hope it wasn't directed at you.
Now, research is suggesting, that epithet is misdirected even for coots because they have suddenly joined crows on the roster of our smartest animals. Scientists now tell us that they are among those rare non-humans that can count.
Crows are already on that list because of an old often-repeated story. Angry at a bothersome crow roosting in his silo, a landowner sought to shoot it. He set up a blind and hid in it but the wily bird saw him enter the blind and stayed away. Thinking that he would fool the crow, the landowner got a friend to enter the blind with him and return alone. Still the crow wouldn't come back. Increasingly irritated, the farmer repeated the experiment with two friends, then three. Not until then was the crow fooled. It seems that the bird could not count beyond three: a fourth man remaining while three departed finally was too much for the crow. It returned to the silo and its demise, an unhappy ending for a counting bird.
Since then, experiments with other crows, jackdaws (crow relatives) and parrots suggest that at least a few individual birds can show number understanding still higher.
But back to coots. They are slate-grey marsh birds with a white bill, at once chicken-like and duck-like. The most commonly observed members of the family of rails and moorhens, they are often seen at this time of year swimming in open water with flocks of ducks. Another name for them is spatterer for their awkward take-off: Bent describes a coot "rising noisily from the water; running along its surface, it beats the water with wings and feet, splashing alternately with its heavy paddles and making the spray fly, until it gains sufficient momentum to fly."
In an early April issue of Nature, an article by biologist Bruce Lyon appeared with the off-putting title: "Egg recognition and counting reduce costs of avian conspecific brood parasitism." I'll try to translate that headline.
Like some other waterfowl, coots are guilty of egg-dumping, that is laying eggs in the nests of other birds of the same species. (In another striking example of this, nesting wood ducks are occasionally overwhelmed with dozens of extra eggs foisted on them by other female woodies.)
Coots respond to egg dumping in quite remarkable ways that are apparently unique to this species.
They normally lay 8-12 eggs and here is where their counting comes to bear. When they are parasitized by other coots, the females are about equally divided between what Lyon calls acceptors and rejecters. The acceptors incorporate the foreign (parasitized) eggs and reduce the number they lay themselves to retain the 8-12 clutch size. The rejecters push aside or bury the foreign eggs and lay their own 8-12 eggs. In each case their brood remains the same as that of non-parasitized coots.
Lyon claims that
this demonstrates two things: Those claims make sense to me, but you'll have to decide whether or
not you agree with them.
Those claims make sense to me, but you'll have to decide whether or not you agree with them.
In any case, Lyon tells us, the rejecter's strategy has evolutionary importance, because about half of coot chicks in his study died of starvation. This "indicates that each successful parasitic chick survives at the expense of a host chick -- a one-for-one substitution."
We'd better change that designation to "smart as a coot."-- Gerry Rising