A History of the Birds of New Zealand.
Plotus Novæ Hollandiæ. — (Australian Darter.)
Plotus Novæ Hollandiæ.
New-Holland Darter, Lath. Gen. Hist. vol. x. p. 453 (1824).
Plotus novæ hollandiæ, Gould, Proc. Z. S. part xv. p. 34 (1847).
Exempl. ex N. Z. Viridescenti-niger: dorso brunnescente lavato: gulâ maculis albis sagittiformibus notatâ: fasciâ latâ albâ a basi mandibularum usque ad latera colli extensâ: scapularibus lanceolatis, medialiter griseo-albis, latè nigro marginatis: gutture imo rufo lavato.
New-Zealand specimen. Crown, nape, hind part of neck, and shoulders blackish brown, mottled with white, each feather being narrowly edged with it; the whole of the back and rump black; quills and tail-feathers black, the inner webs of the former tinged with purplish brown, and the three innermost secondaries with a broad longitudinal stripe of white on their outer vane; bastard quills and the superior primary coverts black, the inner ones slightly tipped with white; the larger secondary coverts are white on their outer webs and beyond the shaft, then, black with a sharply defined edge; the smaller coverts white in their central portion, with a black lanceolate stripe on each web and narrowly margined with white; towards the edge of the wing the feathers are black with a central arrow-head spot of white, becoming entirely greyish white at the carpal flexure; scapulars black with a broad stripe of dull white on their outer webs; the coverts white in their central portion with black shafts, a broad stripe of black on each web with a narrow outer margin of white; throat, fore neck, and all the underparts buffy white; under surface of the wings and tail black. A broad line of black extends from the posterior edge of the eyes down the side of the neck, separating the dark brown of the hind neck from the white plumage of the under surface. The middle tail-feathers, and the innermost scapulars on the outer webs, have a peculiar crimped surface. Bill yellowish horn-colour, brownish towards the base of the upper mandible; the inner cutting-edges of both mandibles armed with minute sharp barbs inclined backwards. Feet dull yellow, shaded with brown; claws yellowish brown. Total length (approximately) 40 inches; wing, from flexure, 14; tail (consisting of eight feathers) 10; culmen 3·15; bill, along the edge of lower mandible 4·25; tarsus 2; longest toe and claw 3·8; hind toe and claw 1·5.
The Canterbury Museum contains a roughly prepared skin of the Australian Darter (Plotus novæ hollandiæ) obtained under circumstances which leave no doubt in my mind of the occurrence of this bird as a straggler in New Zealand.
The late Mr. F. R. Fuller, an excellent taxidermist attached to the Museum, during a visit to Hokitika in January 1874, found the skin stretched flat and nailed up inside an old shed. He brought it away, but could get no information as to how it came there. An examination of the skin shows clearly that it was in a fresh state when affixed to the wall, the edges having, in the process of drying, shrunk away from the nails on both sides.
It would seem that some digger or working settler, probably attracted by the rarity of the bird, had adopted this rude mode of preserving it. At any rate the skinning-operation appears to have been performed by unskilful hands, an open slit having been made from the hind part of the head right down the back to the root of the tail.
The suggestion will occur that the bird may have come down from Australia in some vessel; but the condition of the tail-feathers, which to the very tips are clean and unbroken, proves, I think, that page 176 this was no caged bird. Those who have kept birds of this class in captivity know how soon the tail-feathers in particular get soiled and abraded. The almost entire absence of fat on the inner surface of the skin would seem to indicate that the bird had performed a long journey on the wing; although this may be otherwise accounted for on the supposition of its being a female in breeding condition. The plumage of this specimen, of which a description is given above, allows of its being either an adult female or a young bird of the first year, at which stage the sexes are alike.
I may here mention that the late Sir J. von Haast, during his exploration of the Southern Alps in the summer of 1862, met with a bird in the Ohau Lake, swimming very low in the water, which he was unable at the time to identify, and that the above discovery convinced him it was a Plotus.
The habitat of Plotus novæ hollandiæ, according to Gould (Handb. B. Austr. ii. p. 496), is confined to the colonies of South Australia and New South Wales, where it is thinly but generally dispersed in all situations suitable to its habits, such as the upper parts of armlets of the sea, the rivers of the interior, extensive water-holes, and deep lagoons. This writer adds:—“Shy and seclusive in disposition, it usually takes up its abode in localities little frequented by man; seeks its prey in the water, dives with the greatest ease to the bottom of the deepest pools, and is as active in this element as can well be imagined. It ordinarily swims with a considerable portion of the body above the surface of the water, but upon being disturbed immediately sinks beneath it, leaving the head and neck only to be seen, and these, from their form and the motion communicated to them by the action of swimming, present a close resemblance to those of a snake*. Its food consists of fish, aquatic insects, newts, frogs, &c. After feeding it perches on a snag of some fallen tree in the water, or on the naked branch of a tree in the forest nigh to its haunts, often on one of the greatest height, where it sits motionless for hours together: while thus perched it is much more easily approached and shot than on the water, where it is wary in the extreme.”
The male differs from the female in having the breast and neck black with an arrow-head mark of white on the throat, and a broad stripe of the same from the base of the mandibles on each side of the upper neck; also in having rusty red stains on the underside of the throat.
* There is a special mechanism in the neck of the Darter which gives it a peculiar “kink” in the middle. The connection between this specialized character and the natural habits of the bird has been well explained by the late Mr. W. A. Forbes as follows:—
“The Darters feed entirely, so far as I have been able to observe, under water. Swimming with its wings half expanded, though locomotion is effected entirely by the feet, the bird pursues his prey (small fishes) with a peculiar ‘darting’ or jerky action of the head and neck, which may be compared to that of a man poising a spear or harpoon before throwing it. Arrived within striking-distance, the Darter suddenly transfixes, in fact bayonets, the fish on the tip of its beak with marvellous dexterity, and then immediately comes to the surface, where the fish is shaken off the beak by jerking of the head and neck (repeated till successful), thrown upwards, and swallowed, usually head first. A study of the neck in the recently dead bird leaves little doubt as to the mechanism by which this peculiar impaling of the prey is effected. The 8th cervical vertebra is articulated with the 7th in such a way that the two cannot naturally be got to lie in the same line, but form an angle, open forwards, of about 145°, when the two bones are stretched as far as is possible in that direction. Behind, its articulation with the 9th cervical is such as to permit it to be bent back at an angle a little greater than 90° with that vertebra, beyond which extent, however, no further flexion is possible. The 8th vertebra is thus so articulated with the 7th anteriorly and the 9th posteriorly as to allow it, when the neck is flexed, to be nearly at right angles to the rest of the neck, the two portions of which, though parallel, are then at different horizons, something like the two bars of a parallel ruler. When the neck is bent in this Z-shaped form, any opening-out of the anterior angular bend by the action of the anterior neck-muscles causes the anterior moiety of the neck to suddenly shoot out, thus causing a corresponding protrusion of the head and beak. By the flexion of the 6th on the 7th, and of the 9th on the 10th cervical vertebræ, the curve of the neck is increased—the articulations of the 8th vertebra still forming the double hinge round which motion takes place—and the impaling action correspondingly augmented. This protrusion, though only for a short distance, is so violent as to effectually ‘strike’ the fish which the bird is pursuing.” (Proc. Z. S. 1882, pp. 210–212.)