Part 18

The purple martin supplies another example. The nest boxes we put up for them supply their main breeding places in some areas. "The parents have a habit of collecting many green leaves and placing them in the nest, a practice which may tend by evaporation to reduce the heat" in the next box. "Where large colonies are breeding they sometimes injure pear trees by stripping certain branches of their leaves," according to E. H. Forbush.

A Madagascar weaverbird provides an example of decorating the nest entrance of a quite different type of nest; in this case the nest is in the shape of an inverted retort, with the entrance through the spout. The entrance is decorated with green grass heads or with green leaves, and the males keep adding fresh green decorations even when the eggs are being incubated by the female.

It seems hard to believe that this is really decoration, that it is not for some purpose--either connected with the raising of the young, or more probably a leisure or substitute activity--something to keep the bird busy and strengthen the bond between bird and nest when it is not otherwise directly occupied with nesting activities.

CURIOSITY IN BIRDS

Being unable to ask birds questions that will receive answers, we have to judge their motives from appearances. And from the way some birds act curiosity seems a strong motivation at times. They show a disposition to inquire into things, especially strange things.

Young blue jays that I've raised and studied are among the most prying, investigating, inquisitive birds I've known. When well fed they devoted much time to examining things. Humans, of course, would examine objects by picking them up in their hands, looking at and feeling them, perhaps tasting them. The jays, with more limited equipment, would examine them with bill and eye. When the jays were very young their toes interested them. They pecked at and twisted their own and their neighbor's toes. Pencils and crayons on my desk appeared to interest them particularly. These they were continually pulling about and pecking at. They went about picking at lines on paper, knotholes in the walls of their cage, the red letters printed on a bottle label, and the buttons on our clothes. Cigarettes they liked to investigate by pulling them to pieces. It looked as if the jays were interested in finding out about the things around them by touch and taste as much as they could.

LURED INTO DANGER Compared with jays, ducks seem rather stolid creatures, but they have curiosity too. This was well known to the old-time duck hunters who capitalized on it in duck shooting. The technique is known as "tolling" and I've used two variations of it in museum collecting.

Once on a little mountain lake in New Guinea I found a pair of ducks of a rare species I especially needed for our collection. I stalked them to the farthest bit of cover I could reach, a tussock of grass on the lake margin, behind which I lay concealed. But the ducks were still too far away for me to reach, and their feeding did not seem to be drawing them nearer. I remembered the gunners' trick of tolling, and tried it. I took out my white handkerchief, held it above the tussock of grass while I kept well hidden, and waved the handkerchief back and forth. The response was surprisingly prompt and gratifying. The two ducks turned at once and swam right in to me so that I secured them without any trouble.

Once on a lake in central New York State there was a flock of scaup ducks swimming well offshore. It looked as if they never would come in near the bank. Quite by accident a setter dog that accompanied us began to cavort along the beach. Again the ducks turned and the whole flock came swimming in. Only then did I remember that among old-time gunners there was the practice of using a dog thus, a dog that was even trained for the purpose, to jump high and run about very conspicuously while the ducks were far out, and as the ducks came swimming in, to keep lower and frisk about partly concealed so that the ducks would have to come close to satisfy their curiosity.

REFERENCES

Is it true? Did it really happen? The implications and correlations are my own, and some of the accounts on the previous pages are based on my experiences. But many of the facts come from the writings of others. Where the incidents are well known no documentation is given. But when the behavior described is little known or only recently discovered I've given a reference so that the source can be consulted. These are arranged under the appropriate chapter headings.

BIRDS USING TOOLS

Edna Fisher, Jour. Mammalogy, Vol. 20, p. 21 (sea otter). P. A. Gilbert, 1939, Emu, Vol. 39, pp. 18-22 (satin bower bird). D. Lack, 1947, Darwin's Finches, p. 59 (woodpecker finch). D. Morris, 1954, British Birds, Vol. 47, p. 33 (song thrush). A. C. Bent, 1921, U. S. Natl. Mus. Bull. 113, p. 111 (gull and crow).

BIRDS AS BRIGANDS

A. L. Rand, 1954, Fieldiana-Zoology (Chicago), Vol. 36, p. 35 (eagle, skua, frigate bird).

BIRDS BATHING

F. N. Bassett, 1922, Condor, Vol. 24, p. 63 (hummingbirds). A. C. Bent, 1937, U. S. Natl. Mus. Bull., 167, p. 370 (osprey).

HOW BIRDS ANOINT THEIR FEATHERS

W. L. McAtee, 1938, Auk, Vol. 55, p. 98 (review).

TRAVELING BIRDS' NESTS

H. S. Swarth, 1935, Condor, Vol. 37, p. 84 (barn swallows). M. A. Common, 1942, Auk, Vol. 59, p. 43 (tree swallow). D. L. Serventy and H. M. Whittell, 1948, Birds of Western Australia, p. 243 (welcome swallow).

MALADAPTATION IN BIRDS

J. Grinnell, 1926, Condor, Vol. 28, p. 97 (robin). W. H. Bergtold, 1930, Auk, Vol. 47, p. 571 (robin). H. W. Henshaw, 1921, Condor, Vol. 23, p. 109 (California woodpecker). D. Bannerman, 1933, Birds Tropical West Africa, Vol. 3, p. 415 (thick-billed honey-guide).

FEATHERED BABY SITTERS AND CO-OP NURSERY NESTS

D. Davis, 1940, Auk, Vol. 57, p. 179 (ani). A. C. Bent, 1925, U. S. Natl. Mus. Bull., 130, p. 85 (eider duck). R. C. Murphy, 1936, Oceanic Birds of South America, Vol. 1, p. 398 (penguins).

BIRDS' NESTS AND THEIR SOUP

Gibson-Hill, 1948, Malay. Nat. Jour., Vol. 3, p. 190; F. H. Giles, 1935, Jour. Siam Soc. Nat. Hist. Suppl., Vol. 10, p. 137; and Jabouille, 1931, L'Oiseau et Rev. Franc. d'Ornith., Vol. 1, n.s., p. 219 (swiftlets).

WALLED WIVES OF HORNBILLS