A CENSUS OF THE BIRDS

New Zealand Listener, Volume 1, Issue 26, 22 December 1939, Page 27

A CENSUS OF THE BIRDS

Holiday Suggestion From Dunedin

A Dunedin nature-lover, Mrs. M. J. Marples, has been telling Otago folk how to enjoy their holidays. Here is one of her suggestions, taken from a recent talk from 4YA. HE study of animal communities | doesn’t require specialised knowledge. You don’t need to be able to identify many species. If you can recognise the common birds when you see them you can study the bird community. Again, you can spend as much or as little time as you want, and if you are looking for common forms you've no difficulty in finding them. And if your results are reliable, that is if your studies have been done to your best ability, and you have noted your errors, then you can make a real contribution to knowledge, which will be of value to workers both in New Zealand and in all parts of the world. That is the beauty of the study of natural life. You don’t need any apparatus, to speak of, and you don’t need special training, all you need is a real interest in the subject, a little patience, and the ability to complete what you have begun. Let me describe to you a piece of work I took part in in England, so that you can see the sort of thing I mean, Rules of the Game My husband and I were staying in the country, and we decided to make a census of birds. We chose a definite area which we could survey thoroughly in about an hour. It consisted of a strip of woodland or bush about 50 yards wide on the edge of a river and also the two paddocks adjoining the bush and a-strip of lane beyond. Our aim was to find out the number of birds living on this area. Now I know you're saying, " Well, how do you know that the birds aren’t just flying over or that they'll be the same to-morrow?" Just wait a bit and I'll tell you. There ‘are certain rules to be observed in this game and there is of course a big margin of error, but not half as much as you think! The way we made the census was this. We walked slowly along, each carrying a paper on which was already written the names of all the common species which we felt sure would be there. This made it easier to note the birds, because each time we saw one of these species we only had to put a tick by its name, As we came across a bird we shouted out its name and number and the direction it was going in. For example, " Two blackbirds, gone back. One chaffinch, gone forward." In this way we checked up on each other’s lists and we didn’t count the bird until it had flown behind us. Now this method of counting birds would be impossible if it were not for one thing. Most birds as a rule don't move about very much, particularly during the summer when they are nesting and bringing up their families. They have a definite area and they stay put on that. This is not a hard and fast rule of course, but it is true enough to make a census possible. The disturbance you make walking along and counting the birds is not sufficient usually to drive

them off their own area and therefore the danger of counting the same birds twice is greatly reduced. The Second Attempt Well, we walked very carefully over the area we had chosen, not very’ fast, but not too slowly, and we counted all the birds we saw. We kept separate the numbers of each species in each part of the area, that is, on one page we noted the birds in the stretch of bush and on another the birds in each hedge of the paddocks. The whole thing took under two hours to do. The next day at the same time we did exactly the same thing again, and the interesting and hopeful thing about this second attempt was that the results were amazingly like those of the first day. For instance, we found three pairs of chaffinches in the bush stretch on the first day and three pairs turned up on the second day in approximately the same places. Of course, the results were not identical on the two days; an owl flew out of a hollow tree on the first day and we didn’t see it on the second, and there were other variations of the same sort. But it was awfully entertaining on the second day to think, "Now there ought to be a pair of Yellowhammers in this piece of hedge," and to find them at the place where you had expected them.