NATURE NOTES

Evening Post, Volume CXXX, Issue 6, 6 July 1940, Page 9

NATURE NOTES

A UNIQUE BIRD

BILL TURNED TO ONE SIDE

(By R. H. D. Stidolph.)

New Z?aland possesses a remarkable bird of the plover family, the only bird in the world with its bill turned to one side. It is known as the wrybill plover. During the non-breeding season it spends its time in the North Island, mostly on mud and sand flats on estuaries, and at the mouths of rivers. Judging from the absence of reports received about. the wrybill, however, it must be one of the least known of New Zealand's birds. This i- not surprising in a way, as its habits do not bring it in contact very much with human beings. Its winter haunts are not frequented to any extent by residents of the neighbourhood nor are its breeding grounds on the river-beds of the Canterbury district visited except by anglers. The wrybill is not known to breed beyond, the confines of two or three of the more extensive shingle river beds of Canterbury arid as even there.it is sparsely distributed, the total number 'of ' the species cannot be very large. Consequently in its winter feeding grounds in the

North Island, mostly, if not entirely in the Auckland district, it passes unnoticed. RARE IN WELLINGTON PROVINCE. The waiter has never come across the wrybill in the Wellington district, though it is occasionally seen in the province, probably when on passage to and from its winter and summer haunts. Some years ago,, several were seen at the mouth of the Waikanae River. These birds were evidently tired, as they were resting on the beach and allowed a close approach. Not far beyond the boundaries of Wellington Province, the wrybill has been encountered at the mouth of Porangahau River, on the East Coast, and, according to report, at least small parties spend the winter there and some remain until October at the latest. The main body, however, retire to the more extensive harbours. of the Auckland district, where the conditions are much more favourable. It is not surprising, under the.circumstances, that the .wrybill is such a rare bird in the Welling-1 ton district, as there are. few areas suitable for it. Of. course, -it may be passed ov^ in some instances for the banded dotterel in winter plumage, as it is not unlike that: bird and has a call very much, the same. In the breeding season, the wrybill has a distinctive ■ black band on the chest, whereas the banded dotterel has two bands, one chestnut and the other black.- ~. • • * PECULIAR BILL. ■ The slender bill of the wrybill is turned to the right;, the .bend com-

mences about the middle, and for the remaining third of its length it is deflected about 12 degrees. One of New Zealand's earliest naturalists, the late Mr. T. H. Potts, who observed this bird in Canterbury, writing about the peculiar form of the bill, said that the horny point of the bill was sufficiently strong to be used for thrusting between and under stones and pebbles. The flexibility of the upper mandible, derived from the long grooves and flattened form (extending for nearly half its length), tended materially to assist the bird in putting its curved bill close to a stone and thus aided it in searching or fossick-

ing around or beneath the shingle for its food, while at the same time the closed mandibles '♦ formed a tube through which water and insects could be drawn up, as water is sucked up by a syringe. As the"flexure of the bill was lateral, the bird was enabled to follow up retreating insects by making the circuit of a water-worn stone with far greater ease than if it had a straight beak. The singular form of bill, Mr. Potts stated, far from being an accidental deformity, was a beautiful provision of Nature, which conferred on the. bird the advantage of being able to secure food

from sources whence it would be otherwise unattainable. ADVANTAGES LIMITED. A more recent investigator of the habits of the wrybill, Mr. E. F. Stead, expresses his doubts as to the value of this. pec.uliar bill. Although he has watched the wrybill feeding among stones in the river-bed and has noticed that under certain circumstances the ■bent bill is of some use, he points out that in others the bill is a disadvantage. He has seen a wrybill peck under a stone on" its left and then turn round to reach the same stone on its right. Moreover, he has watched the banded dotterel, which has a nor-mal-shaped bill, act in the same manner, so that, as he points' out, any advantage the wrybill gains is very slight. A bill turned to the right is of some advantage, he states, when the bird is feeding under stones on its right, but it is a distinct disadvantage when feeding on its left. In his opinion, the coloration of the wrybill is of more importance, as it harmonises so well w.ith the surroundings in which the bird ... breeds that if the bird , remains still,- as it, Often does, it is exceedingly difficult to detect. In addition, for half'the year the wrybill frequents sand. or mud • flats, where the bill is of no special advantage. What, then, .is'the purpose of this peculiar bill? • ■ o •' • • . * * » BREEDING HABITS. It, was:Mr. Potts who first described the '.breeding: habits of the • wrybill. He recorded; that; its nesting; place would; be discovered -with little difficulty'

were it net for the wonderful instinct it exhibited in selecting the ground for depositing its eggs, which ■were laid, without any preparation, among the pebbles of a river-bed usually and never far from water.' So well does the grey tint of the eggs harmonise with the general colour of the shingle around them that their detection would be almost hopeless if the bird were less confident. Mr. Potts stated . that the young ones, if undisturbed, remained for some time near the spot where they were hatched and in order to escape observation they concealed themselves behind stones. Should an attempt be made to molest them, they start ,off with considerable celerity, uttering at the same time a shrill piping cry of alarm. When hard pressed they take -to the water, and Mr. Potts has known them to cross a stream of considerable volume. The \ wrybill, he stated, becomes so tame during' the breeding season that after the eggs have been picked up, examined, and replaced on their unsheltered sandy bed, he has seen the" old bird immediately resume her duty of incubation, though he had removed but" a few paces away. I