NATURE NOTES.

New Zealand Herald, Volume XLVIII, Issue 14751, 5 August 1911, Page 5 (Supplement)

NATURE NOTES.

BIRDS' BILLS. BY ? JAMES DETJJIMOSri), I-.L-S., F.Z-8. ' There is a great deal more in a bird'i bill' than meets the eye. Like the . : : feathers, the claw, the musical organ, and many other parts of a bird, it is a* deep and interesting • study. In shape, size, structure, modifications and developments it has almost endless 'variations. .■: The f cause of many of these, it must be confessed, has defied the most painstaking • ' investigations of the most capable investin | gators and the hardest thinkers of these ■;>' j times. The key that will unlock ' all the mysteries associated with a bird's bill has I not yet been found, and here,' as much, - ' • perhaps, as in any other department of science, there, is room for brilliant work. To the bird, its _ bill is arm, hand, tool, and weapon. ■, It is used primarily for, the purpose of securing food, second for the erection of dwellings, and thirdly,, in moet cases, .as a weapon of defence : or offence according to the ownor's dis-, position. It is as a food-gatherer that the bill is generally regarded, and in that capacity its modifications • and adapta- , tions' are largely explained. _ • In many cases the explanations are fairly satisfy* ing; in others they are met with objections that leave the inquirer as greatly, « puzzled as when he began. - It would be interesting to know whj birds lost their teeth. No birds at pre-; sent in existence possess true teeth, although, apparently, ' these equipments would be as useful to them as to any other animals. We know that birds were not behind the door when teeth were given out, as three very famous extinct,. birds . had well-defined teeth. The most notable of these is Archeopteryx, the oldest bird of which the world has any -record. Its remains have been found in two slabs of slate in . Solenhofen, Bavaria, Germany. It was about the size of an English crow, or rook. Its bill was short and blunt, and the upper jaw was furnished.: with thirteen teeth, while the lower jaw had ; three teeth on each side. Heeperornis, " The bird of the West," a diver five feet long, which left its bones in rocks in Western Kansas, United States, some four million years ago, had good sets of teeth; and Ichthyornis, " fish bird," which has also helped to make the rocks of Kansas famous, had , strong, sharp teeth, placed in separate sockets, like an alli- .. gator's. These individuals represent the birds of their day,. all of which evidently had testh, which must have been lost , before Tertiary times, and we now find birds absolutely toothless creatures. :.' It would be idle to speculate as to the cause that has brought about this condition, at there is nothing to show that the birds ol to-day are loss in need of teeth than were the birds of old. Perhaps it is . partly to compensate for this loss ; that. the bills of birds we. see / around us arc so varied in shape and _ structure, for ,it cannot bo denied that at . least some of tha remarkable adaptations have been made for utilitarian purposes "ij in order to give birds ' a better chance of earning, an honest living. vi: The ordinary typo of bill, represented •(by that of thai, rook, i may be used for all kinds of, work, s- ■ ' Consequently the look's. diet is of a very general character. Its bill can. deal with _ grain, fruit, meat, insects, berries, small __' ' aquatic animals in pools, ; and many other ; - things. Some time ago I saw . a rook . swoop down on to a clear patch in! my ; garden on which a hen had laid an egg. ; . The rook dived at the egg as sure and i ; as swift as an arrowy drove its powerful ; -pointed bill through, rose again in the air, and flew away over, the hedge with the impaled egg, which no doubt it took to the young "in its nest. ' It is; in other bird families, more restricted in their . • diet, that adaptations can be easily.traced, j The shag, for instance, has a sharp hook V ; : at'the - end > of ; its - bill, '- which must : be : of considerable help to it in' its excursions . • under ; the surface of the water in - search.; of fish. The gannet; a. sea-fowl, seen " in the waters of the North Island of New Zealand much more frequently than in thef waters of the South: Island, plunges upon fish from - a great height, and along the inner edge of its bill is , a series of fine ?- saw-like processes, . pointing backwards, ?; : which ; makes it almost impossible -for a fish onco caught in the bill to escape.'. In T ; the , sheltered I harbours of the Auckland 1 • Islands there is a sea-duck, ' called the• merganser, which possesses :: a ? bill more : like the toothed bill of the old days than ■ the bill of > any other modern bird. At 4 - first V sight this bill seems :to have been equipped with ; large % teeth,. but . a closer examination : shows; that the "teeth" are : merely : serrations ,■ or .. indentations■ in - tho . long, narrow bill. • 1 ; , Other ducks have very, different bills. v , These are broad ar '~ depressed, and have \ .'amellßo, ; which act as a sieve like the whalebone of a whale,{letting the water out but retaining the tiny creatures picked v v up out of 1 the.!' mud and t sand. . This .is specially noticeable in the' shoveller or •; ' spoonbill duck, 1 often seen ,on "the muddy • shores of lakes and streams in both islands. It ris : a surface feeder, never dives for its i food, and feeds on small aquatic insects, which - its peculiar bill, shovel-like- or spoon-like, is adapted to' catch, < and which its exceptionally > long lamella are ; adapted to retain when tha water is allowed to run out. : New Zealand's blue duck, some- ; times i called tho mountain duck, is : distinguished " from - all other ducks in the : world, as far as they are known, by its . bill being furnished * for i halfthe s length with soft folds of a membrane, associated in some way, it is 'thought, with the capture of the larvae of insects. > Whalebirds, often seen ' flying over the : water near tho coasts of New Zealand, with zigzag movements and sharp motions of • the • wings, have a strange fringe of lamell®, .used,apparently, in the same way as a duck's. ■ The kea and the kaka, both true parrots, • have strong, rounded bills*if : These v are : found to be valuable in almost every emergency, from killing a sheep, to chiselling - a way out of. & wooden cage,,or playfully, tearing ' a piece of cloth to ■ tatters. . The morenork ; owl, and the i harrier i?and . the other" hawks, have murderous bills, which;: these birds of ' prey v, probably would: nob { wish .to improve upon. , / I The wading birds and shore 1 birds of? _ New Zealand supply many different types 1 of bills. The turnstone, named on account) > of . its habit ;cf turning over stones on - r beaches in search of, insect food, has a, . straight, sharp bill. • The; oyster-catcher 1 has a bill of the same shape but- of.a larger size. This bird • also lias received ■ its popular name on-account of the habit the - name suggests. It inserts its 'blade-* j like: mandibles between the shells of a f bivalve, wrenches them, open, and ' feeds Q upon -the fish inside.; The dotterels also a have straight - pointed bills ; the curlew, an- occasional; visitor from Australia, has ,1 'a bill bent down at the tip ; the godwit, J most . famous of migrants, has one bent ! slightly, upwards; . and the avocet, the j M recurvirostra" of has a long, 7 slender, needle bill, with a remarkable curve upwards, like a very pronounced a snub nose. It would be an almost,end- ) „ less task to go into details of the different I kinds of bills worn in New Zealand alone, j _ without mentioning even the most notable ;; « in other centres, such as the skimmer, of r d North American whose lower mandible ex- . tends quite an inch, beyond the point of "■ the npner mandible; the boat-billed heron of tropical America, with r . an a.bsurdly exaggerated bill ~ and the sickle-billed; . humming birds. Coming back to New '* Zealand, this Dominion possesses the meat. • * remarkable bills on record. One is the l bill of the v.'y-billed plover, bent dis,7 'tinctly to one side, a unique abnormality* 1 The others are tho bills of tho hum birds. ' , —the male's short, straight, and , stout, ' the female's long, curved and slender— 1 supplying a wise of sexual dimorphism "unv paralleled in the history of birds. Many i of the peculiarities as stated' if at the beginning of i this article, 7 may bof v . ; explained by the theory that; they have been brought about in order to ,e<r-iip certain birds for certain methods of securf, ing food; . but .this | can hardly be applied' V to all peculiarities of this character, and; ; a the subjects still cajfe fyr I ' , - jp Jl £11 r '.-.if I