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 A HISTORY OF HERTFORDSHIRE corone), a bird which is decidedly on the decrease on account of game preserving. In this district there is Elstree reservoir, a piece of water which has considerable attractions for wildfowl, although not to so great an extent as the reservoirs at Tring. Of the rarer birds which have occurred in Hertfordshire, one at least has never been recorded elsewhere in the British Isles ; this is the rock thrush (Monticola saxatilis). Amongst other rarities which have from time to time been obtained, may be mentioned the woodchat-shrike (Lanius pomeranus), two-barred crossbill (Loxia bifasciata), rustic bunting (Emberiza rustica), roller (Coracias garru/us), glossy ibis (Plegadis falci- nellus], Pallas's sand grouse (Syrrbaptes paradoxus), and Baillon's crake (Porzana bailloni}. I am afraid that the list of disappearing and extinct species includes some very interesting birds. The causes of their disappearance are varied, but all are directly or indirectly due to the influence of man. Of the direct causes, game preserving is responsible for the destruction in many places of birds of prey, though there are fortunately many and increasing instances of game preservers who set a good example by using every effort for the protection of rarer species. The way by which man indirectly destroys and drives away various birds is by enclosing and planting land which was formerly open, and also by the use of the drill and hoe where formerly seed was only scattered broadcast. In those days the great bustard (Otis tardd] and stone-curlew ((Edicnemus crepitans) ran no risk of having their eggs destroyed by the horse-hoe. To the alteration in the aspect of the country caused by planting and enclosures may be partially attributed the non-appearance nowadays of the ' trips ' of dotterel (Eudromias morinellus) which formerly visited the northern hills in the spring and autumn migration, though, no doubt, this can also be accounted for by the decrease of this bird as a breeding species in the British Isles. To turn to the more pleasing side of the picture, one could mention many birds, which quite recently were considered rare, but which now are plentiful. This undoubtedly is in many cases due to the very cause which has been inimical to many of the decreasing species, namely, enclosing, planting, and keeping coverts quiet. With no coverts, we should be without many of our warblers, and should only have such small birds as are partial to more open country, few of which are really fine songsters, and thus we should be unable to enjoy one of the greatest pleasures of the country. Civilization has also increased the number of our resident species in another direction. Canals were first introduced into this country to any great extent by the third Duke of Bridgewater, who lived at Ashridge Park ; and it is to canals that we owe the existence of the reservoirs at Tring, which are for the purpose of keeping up the supply of water in the Grand Junction Canal. These reservoirs, of which there are now four, com- prise about two hundred acres of water, the whole of which, with the exception of about ten acres, is in Hertfordshire. The sporting rights 194