Roadside diners

Why do I always see so many pigeons at the side of the road. Is it because the tractors spill so much wheat or grain?

ANDY CROW replies: There is no doubt that at certain times of the year there are free offerings on the roadside that will attract birds. However, you will see pigeons lining the roadside to collect grit. Digestive enzymes can’t break down certain seeds and grains, so the pigeons eat grit which is stored in their gizzards and used to help grind up the food to aid digestion. As the grit is worn it is passed or regurgitated and the bird stocks up on more.