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Far up the mountain-gorge, where the foaming torrent, walled in on both sides, rushes impetu- 

 ously over its shingle bed, surging around the huge water-worn boulders that obstruct its course, 

 and forming alternately shallow rapids and pools of deep water, there the Blue Duck is perfectly 

 at home ; and its peculiar whistling or sibilant note may be readily distinguished amidst the noise 

 of the rushing waters ; indeed, as Mr. Travers has already suggested, the bird appears to have 

 been specially endowed with this singular note in consequence of its frequenting such localities. 

 A stray one is sometimes carried down during a freshet into the still reaches, or even to the very 

 mouth of the stream ; but it speedily works its way back again to its favourite mountain haunts. 

 It is a very tame or stupid bird, often remaining perfectly quiet on a projecting boulder till you 

 approach vrithin a few feet of it ; then, sidling off into the water, it swims into the nearest rapid 

 and allows itself to be hurried down by the current. It seldom dives, and takes wing only when 

 fired at or closely pressed ; but it swims with considerable rapidity, the head being carried low 

 and inclined somewhat forward. It has the faculty of turning itself round in the water, and 

 without losing ground, however rapid the stream, as though its body were worked on a pivot — a 

 performance, no doubt, aided by the peculiar lengthened shape of its tail. It climbs the slippery 

 face of the rocks with facility, assisting itself in the ascent by its wings, which are armed at the 

 flexure with a hard protuberance or knob. As already mentioned, it utters a peculiar whistling 

 note, from which it derives its native name. 



I believe this Duck is to be found at the sources of all our mountain-streams ; for although 

 I never succeeded in getting a specimen at the far north, its name was perfectly familiar to the 

 natives of that part of the country. It does not, however, occur out of New Zealand, nor has it 

 any known ally. 



In the autumn of 1863, I visited the upper gorges of the Manawatu river and obtained a 

 fine series of specimens in the various states of plumage. The crops of those I opened were 

 filled with a species of " caddis-worm ; " on turning out the contents, I discovered the nest 

 of this insect, consisting of a tough integument, shielded by small angular stones firmly glued 

 over the entire surface. The " caddis-worms " were of different sizes (none, however, exceeding 

 an inch in length), light brown in colour, with a dark head, armed with three nuchal plates, and 

 furnished with six legs. This insect appears to exist abundantly in all our shingle-rivers ; and as 

 we may assume that it forms the chief if not only the food of the Blue Duck, the troublesome 

 task of dislodging the animal from its stone-covered cell appears to explain at once the use of the 

 fleshy membrane which fringes the bill of this bird. That it is at any rate an expert may be 

 inferred from the fact that, out of several hundred specimens taken from the crops of my birds, 

 only one of these insects was invested with the case or integument, this having probably been 

 swallowed by accident among the rest. 



Mr. Potts states that on examining an embryo of three weeks he found the form of the bill 

 well developed, showing on the sides, near the end of the upper mandible, the peculiar mem- 

 branous appendage of a darker colour than the rest of the bill, but that he was unable to 

 discern the presence of lamellae ; the caudal down was produced to a marked degree. The same 

 accurate observer has furnished the following interesting account of the breeding-habits of this 

 species : — " Sometimes it is a burrower ; and its nest may then be found in a hole in a bank. 



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