Counting geese on the ground in fields is easier than counting flying birds – they will not at once disappear from your field of view. But at the same time the geese in a large flock on the ground may be behind each other and the birds farther away may stay unnoticed. Often the geese in a field seem like a narrow band but on seeing the flock from another side it turns out that the goose flock covers a much greater area than supposed, the flock is as long as it is broad and at least half the birds were not noticed at all.

Because of this it is best to count birds on the ground (or water) from for instance a birdwatching tower or a higher slope. An attempt can be made to count a flock from several angles but such a hemming in can instead scare the birds into flight. This should certainly be avoided.

Counting of flying bird flocks is more complicated because the time available for counting is only a few seconds, rarely tens of seconds. Experienced birdwatchers in such a case count only a small part of the flock and estimate how many flocks of such size the large flock could hold. For instance in case of a hundred-bird flock ten birds are counted and then the number of tens in the flock is estimated. In thousand-bird flocks the birds are usually counted by hundreds.

In large flocks the birds constantly change their places in flight, some of them are not visible behind the others and in a hurried situation there is too little time even for counting by hundreds – these conditions together make the counting of large flocks complicated. In counting large flocks the number of birds always tends to be underestimated and the larger flock the greater the underestimate. But with regular training in bird counting experience is gained and the result becomes more precise.

For training in counting birds several computer games have been set up. You will find one of them on the  web page of the Estonian Ornithological Society. Happy training!