Information on extant specimens of haggis is at http://haggis.ca/food/

Documentation on the haggis ( Haggis haggis caledonensis, L.) is extensive but gives varying accounts of its anatomy. Perhaps the commonest conception of it is as a small three-legged animal having one leg somewhat longer than the others such that it can conveniently run around the Scottish hills in a clockwise direction. The haggis hunting technique called for great stealth in that the hunter would creep up behind the unsuspecting beast until he approached within three kilt-lengths of it, whereupon he gave vent to a loud sound, produced either by the vocal outburst "gu dearbh!" (freely translated "gotcher") or, in the case of more accomplished hunters, by a sustained note on the bagpipe chanter, with rapidly interpolated grace notes at a frequency interval 25/27 lower, this somewhat eerie sound being said to resemble the call of a long-extinct predatory relative of the curlew ( Numenius arquata, L.) - also known in Scotland as the "whaup". Only out-of-province hunters would think of taking a complete set of bagpipes on the hill, because of the considerable encumbrance they presented during the stalking.
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When the sound had been made, the haggis, surprised, would turn suddenly around and, now unbalanced because of his new attitude upon the slope of the hill, would generally fall over and be unable to regain his feet before capture.
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It appears that, as a result of this predation, an evolutionary trend developed in the haggis whereby the beast became more adept at looking behind without moving his feet. While some have attributed this adaptation to interbreeding with the short-eared owl ( Asio flammeus, L.), no serious credence can be given to this suggestion as the mechanism of turning in the haggis must have arisen from greater flexibility in the pelvic joints rather than in the neck (which, it can be asserted without reasonable doubt, was never part of the haggis anatomy).
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As a result of its greater elusiveness, the haggis began to disappear from the dinner table. Fortuitously, at this time, it was discovered that a reasonable synthesis could be achieved by the mixing of local grains with the finely chopped pluck of a sheep. Even the original appearance of the table-dressed haggis was realised in facsimile by the introduction of this mixture into the sheep's stomach or intestine, thus making it, at the same time. the first boil-in-bag convenience food.
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The coming of the 20th century saw the introduction of plastic substitutes for the intestine bag (which had always been prone to rupture while boiling) and many haggises are now made this way. It is held, however, that a more convenient way to cook haggis is to use a pudding basin to hold the mixture and thus boil it in a similar way to a steamed (or Christmas) pudding. To some extent this avoids the pretence that the genuine Haggis haggis caledonensis is being served up, an affectation which will not impress many people, as it is widely known that the retiring animal is now a protected species, sighted but rarely in the remoter parts of the Scottish Highlands and thought, though not proven, to exist in parts of Cape Breton Island and Otago
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You may care to look at the current availability of specimens of haggis.
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The above document was first published by Alasdair McKay in 1977 and has since been plagiarised extensively by other writers. Permission to circulate the text is freely given provided that the origin is acknowledged and the author's name together with this notice is always attached to the text.