NATURAL HISTORY NOTES

Otago Daily Times, Issue 23577, 13 August 1938, Page 5

NATURAL HISTORY NOTES

Written for the Otago Patty Times V. By David H. Graham '' 1 ' : v : ;^-;gannets Mr A. R. Jones, of Broad Bay, has written an interesting letter in which h© says he: has seen some gannets diving in Otago Harbour, and asks if they are a rarity in these parts. Gannets are by no means common in. Otago Harbour, but the writer saw occasional pairs while he was working a launch between Portobello and the Otago Heads, and more often and in greater numbers between the latter place and Cape Saunders, especially during the times when shoals of sprats and pilchards were migrating northwards. The food of gannets consists mainly of sprats, pilchards, mullet, garfish; herrings, and small red cod but squid are also caught when they are swimming close to the surface, arid are caught by diving in a most spectacular manner. . A flock of gannets ibombarding a shoal of fish in deep water is a most interesting sight which the observer is never tired of watching. Although gannets i may be watched diving for fish in the Otago Harbour, one cannot see them at their best in such shallow water, where they do not rise to more than a few feet and more often as-not dive in a slanting direction.; Off; shore in deep water the gaririet flies rapidly over the water and begins to soar at a height of from 30 to 100 feet. At the plunge the head is pointed down, the tail up; the wings are slightly spread, so that the bird appears, like a great winged arrow. When it has almost reached the water the wings are closed tightly to the body, and great spurts of water may be seen from, five to ten feet in height. The contact of their wings, suddenly closed before entering the water, sounds like a loud handclap. When the waters have subsided after the splash and all is still, 'the bird; suddenly and buoyantly,'(Somes to' the surface, the head and,neck stretched out first.'.lt then sits quietly on the water to finish swallowing, its orey and to rest, then slowly and laboriously rises to windward With its long neck and tail stretched to their full extent. Gaining a height of 30 or more feet, it swings round to leeward and is soon. ; ,sparing again, looking for more of its prey. One observer. with a stop-watch took the length of time a gariftet could stop under water after:':'-.ijie plunge; the limit was seven*' seconds, and the average six seconds. The same observer also tinted gannets in several descents from a height of perhaps 60 feet and found it took the bird froin. bris to-one and a-half seconds frorri.the beginning of the descent to the" time when it struck the water. This"%'dicates that;the gari.net actu-aUy-;;!<*ces or throws itself, downr wards a* the distance travelled is too great ;for quick descent by gravity alone;. Sometimes two birds will de? scend at an angle aiming at the same fish, and how they avoid aririibilatr ing each other seems: marvellous. Onejcarinot hut: how this large : ' ! sdi^H'roM-such'.'a height at such a tremendous speed without injuring itself, but the gannet is well protected against bodily injury in its terrific plunges by a strong elastic cushion, of air cells under the skin of its breast, which softens the shock' of impact as it strikes; the water. ■, •. i ', Towatch ajflojck & gannets feeding,jasitheiwaiter bj£? done in the Bay of; is $ fascinating sight. A continual stream:of birds drops into \the water, which is kept in constant agitation, while after each dive the bird returns to the flpck, thus maintaining the circulation. The flight of the gannet is a magnificent performance as the bird soars aloft on its long, pointed, blacktipped wings, its spear-like head and beak, arid its slender tapering tail offering little resistance to the air, as it sweeps in great circles far above the sea until almost lost to sight in the sky. When travelling it flies close to the water, flapping its wings,, which at intervals are fully outstretched. It is well built for speed and its flight is powerful and long sustained. Its peculiar shape, forming an almost perfect cross while it is soaring, serves to identify it, as far as this can be seen. '■'■■':'■

The total length of the adult gannet is about 33 inches, the extent of wing 70 inches, and the length of the bill 10 inches. Itu weight is about 31b. The plumage as a whole is snowy white, but the crown of the head and the neck are golden buff. The primaries, secondaries and four central tail feathers are brownish black, with white shafts darkening towards the tip. The feet are dark brown with a broad line of bright greenish yellow down' the front, continued on to the toes. Ganhets are web-footed birds of the same family as pelicans and cormorants; the genus mcludes eight species from temperate and cold seas. The New Zealand species is most common in the north of the North Island, but may be seen from there in smaller numbers down to Stewart Island, and it is said to breed on Solandef Islets. Although the gannet is mainly a coastal bird, it enters harbours and estuaries. In the gannet we have a combination of elegance and cluminess mixed. One minute we have a beautiful, joyous, gliding, graceful creature in the air and water, but when it is on land this graceful bird turns into a clumsy waddling animal; Its metamorphosis is extraordinary It is possible to approach these birds with a little caution while they are. nesting on fheir breeding grounds, but if one came too close, the bird would move awkwardly away, and if the person continued to harass it, it would back away, uttering a variety of loud, guttural croaks or grunts, until it could flop over the edge of the cliff, spread out its wings, and sail gracefully out into space—a sudden transformation from an Ungainly, awkward, sfupid fpwl, to an elegant, soaring sea bird, riding at ease on its broad, powerful wings, one of Nature's triumphs in the balancing of forces. Gannets' nests in New Zealand are placed on small mounds of guano and earth, four to six inches in

height, and distant about two feet and a-half from each other. The mounds are composed of compacted earth, guano, and seaweed, added to each year by more guano and seaweed.

On one occasion Dr W. R. B. Oliver found young birds just hatched, but there were also fresh eggs and large chicks covered with white down. The newly-hatched gannet is an unattractive object, fat, shapeless and helpless. It is carefully brooded by either' parent,, for it must be protected from the hot sun and shielded from rain and coldness until, in the course of about three weeks, its protective coat of soft, white down completely covers the body. The young is well fed by the parents, and when one or the other comes in from a fishing expedition the very young bird is assisted by the parent almost scooping food into its mouth in order, to feed it, but when larger the youngster is able to dive into ,the parent's cavernous mouth and fish for himself. During the ceremony sometimes a few cheeky gulls will hover round, and often as not, owing to the clumsiness of the baby gannet, get away with its food. The young gannets are few for some three or four months and then left to go hungry for 10 days or a fortnight in order to reduce their weight preparatory to their learning to fly. Before taking off on their first flight, these young birds spend a good deal of time flapping their long wings in order to relax the joints and strengthen the ligaments. When the day comes for their mighty plunge, they half fly, half fall into the water below, and in the sea they remain for some weeks drifting hither and thither. Working their way out to deeper water and higher waves, they take off from the water with a newly-found power, henceforth to find their own livelihood by those beautiful Dlunges which are the admiration of all who see them.