SOME birds know how to use a tool to get food. We may think they are highly intelligent but what they are doing may be inherited, that is, coming from their instinct. The Short-billed Woodpecker Finch uses its bill to catch insects. But if the insects are hiding in deep holes or crevices and are out of its reach, the bird will look for a sharp cactus thorn or a twig to dig out the insects. Little Herons use stones to crack large eggs so they can eat the contents. They pick up the stones with their beaks, raise themselves on tip-toes and let go of the stones. Their young also do this instinctively when they see ostrich eggs but they often miss their target. Their ability improves with practice. Seagulls drop shells and crabs on to hard ground to crack them. A Grey Heron uses pieces of bread as bait for the fish. When the fish come near to eat the bread, the Heron catches them for food. Mynahs and Cattle Egrets in Hong Kong are commonly seen following farmers ploughing the fields or cattle feeding to catch the insects, worms or reptiles disturbed by them. They know they can find food more easily this way than by searching on their own. Is it intelligence or instinct? The fact that birds know how to use ''tools'' to get food indicate they are highly intelligent, but how they behave comes mainly from their instincts, because as birds grow older, they learn to use their ''tools'' more effectively.