England, southern England, decrease, Ireland, disappearance, status, northern Scotland, coastal districts, Pentland Hills, Scotland and Ireland, S. Scotland, increase, 19th century, central England, HOODED CROW, human destruction, Carrion Crow, British birds, Hooded Crows, central Scotland, fluctuations, Outer Hebrides, Scotland, the British Isles
(42) CHANGES IN STATUS AMONG BRITISH BREEDING BIRDS BY W. B. ALEXANDER AND DAVID LACK. INTRODUCTION. IN view of the present interest in animal fluctuations, a survey has been "made of every bird breeding in the British Isles
, to see what proportion of the species have increased, decreased or remained at about the same level during the last one, hundred years. Thanks to a large number of county avifaunists and to a smaller number of biographers of particular species, British breeding birds have been well covered during this period, and it is unlikely that any species would have changed markedly in status without the fact being on record somewhere. Knowledge prior to 1840 is much less complete, but any changes recorded before this date are included in the summaries below. Acknowledgment should be made to an earlier survey of the same subject by E. M. Nicholson (Birds in England, 1926, pp. 25-110). We are also much indebted to Miss L. J . Rintoul and Miss E. V. Baxter for reading through the present paper and for valuable criticisms and additions in regard to status in Scotland. The best evidence for fluctuations occurs in those species which have colonized new areas or deserted former haunts. An increase or decrease of a widespread species is less easily detected, and such a species could probably double or halve its numbers without the fact being noticed. However, any really marked change would probably have been recorded. To keep this paper within reasonable bounds only a very brief summary
is given for each species, but where a detailed survey has been published a reference is given. Purely local changes are omitted; so are changes which can be inferred to have taken place, but which are not documented. From a knowledge of the distribution of woods, agricultural land
, marshes and heaths in, say, the eighteenth century
, it would be possible to infer that many BRITISH BIRDS
have either increased or decreased, but such speculations are omitted unless there is direct evidence for change. Changes during the present war are also not included, as some of them are likely to be only temporary. Causes of fluctuations are added to the summaries where they are known or can be reasonably surmised. Those causes which are noted should not necessarily be considered the sole factors involved, and in some cases the main cause may be some less obvious factor which has been overlooked. Thirty-six species for which there is no evidence of any change in status are omitted from the annotated list, but they are given in the summaries at the end of the paper. They include twentytwo passerine and near-passerine species and fourteen others.
VOL. XXXVIII.] CHANGES IN STATUS.
ANNOTATED LIST. RAVEN (Corvus c. cor ax). Great decrease in first half of igth century, when exterminated over a large area of eastern and Central England
, though a few persisted in Essex till 1890, and in Sussex till a year or two later. Increase in 20th century
in W. and N. and recolonized Sussex in 1939. Main factors human destruction, and decrease of carrion in settled districts, and later protection. HOODED CROW (Corvus c. comix). Marked decrease in southern and central Scotland, due at least partly to human destruction and perhaps to competition with Carrion Crow ; also decreased in many parts of Ireland. But holds its own in wilder parts and in coastal districts of north and west Scotland and islands. CARRION CROW (Corvus c. corone). Locally decreased through human destruction, especially in S. and E. England, but has increased and replaced Rook in outskirts of London, Birmingham and other large towns. In southern and central Scotland has largely replaced Hooded .Crow and has spread to N. Scotland and Isle of Man. The zone of interbreeding between Carrion and Hooded Crows appears to have shifted considerably northward in Scotland, but still remains a narrow belt. ROOK (Corvus f. frugilegus). Has spread to areas in northern Scotland and Ireland
owing to growth of trees in formerly treeless districts, and has colonized Orkney, Skye and Outer Hebrides. JACKDAW (Corvus monedula spermologus). General increase, especially in Scotland, where it has spread west and north and colonized Outer Hebrides and new islands in Orkney. Cause unknown. MAGPIE (Pica p. pica). Marked decrease in 19th century
in some parts of England, especially S. and E., and throughout Scotland. Increase in Ireland, which was colonized towards end of 17th century. Increase in many parts of England and Scotland since 1914. Main cause human destruction or its cessation. BRITISH JAY (Garrulus glandarius rufdergum). Marked decrease generally, especially in Northern England
and Scotland, but with local increases, especially in southern England
since 1914. Cause human destruction or its cessation. "In Ireland G. g. hibemicus was nearly exterminated early in 19th century and in latter half of that century was confined to a limited area in the south-east, but in 20th century has increased and colonized woods in most counties. CHOUGH (Pyrrhocorax p. pyrrhocorax). General decrease extending over two centuries. Main cause unknown. In Scotland, where in 18th century
it occurred in small numbers in numerous inland localities as well as on the coast, particulars as to dates of disappearance are scanty. It lingered
in Sutherland till early in 19th century, in Berwickshire till about 1850, in Skye till beginning of 20th century, and in the extreme south-west till quite recently, but is now confined to the Inner Hebrides. In England, where it seems always to have been confined to the coast, it became extinct in Yorkshire early in 19th century, in Kent and Sussex between 1830 and 1850, in the Isle of Wight
and Cumberland about i860, and in Dorset and S. Devon about 1890. It still survives in decreased numbers in Cornwall and N. Devon, and more commonly in Wales, the Isle of Man and Ireland, but is now confined to the coast except in N. Wales. In some of these areas it appears to be holding its own or' perhaps even increasing. STARLING (Sturnus v. vulgaris). Decrease towards end of 18th century, when became almost extinct in the north of England and the mainland of Scotland except Caithness, but survived, apparently without diminution, in the Shetlands, Orkneys and Hebrides. In Ireland isolated colonies survived on many islands and also on coastal cliffs and ruins, etc., inland. Between about 1830 and i860 recolonized most parts of northern England and southern Scotland
and increased enormously in England, extending west to Cornwall and into western Wales. From that time onwards has continued to increase and has spread into the Highlands of Scotland and many parts of Ireland where it was formerly only a winter visitor
. Cause unknown. As regards Scotland, see Harvie-Brown, J.A. (1895), Ann. Scot. Nat. Hist., pp. 2-22. HAWFINCH (Coccothraustes c. coccotkraustes). Marked spread and increase. Possibly only began breeding in England at beginning of 19th century and in first half of that century was confined to S.E. England and Midlands. Has since spread west to Devon and Wales and north to S. and E. Scotland. Cause unknown. GREENFINCH (Chloris ch. Moris) Increasing and spreading in woods of northern Scotland. BRITISH GOLDFINCH (Carduelis c. britannica). Huge decrease everywhere in 19th century, but in 20th century marked increase in England, southern Scotland and Ireland. Important factors have been the extensive catching of Goldfinches as cage-birds and its cessation, also the spread or decrease of thistles, and the incidence of hard winters. SISKIN (Carduelis spinus). Increasing in Irish woods. LESSER REDPOLL (Carduelis flammea cabaret). Rather small but definite increase throughout Britain. Possible cause is cessation of bird-catching. Also helped, especially in northern Scotland where increase is very marked, by the planting of trees.
VOL. XXXVIIL] CHANGES IN STATUS.
BRITISH TWITE (Carduelis flavirostris pipilans). Marked decrease in N. England and S. Scotland with complete disappearance from some areas, e.g., Cheviots, Pentland Hills. Cause unknown. LINNET (Carduelis c. cannabina). In 19th century decrease in central England and elsewhere, due mainly to bird-catching and decrease of waste land. In 20th century increasing in parts of southern England and perhaps elsewhere, perhaps due to cessation of bird-catching. BRITISH BULLFINCH (Pyrrhula p. nesa). Spreading in woods in northern Scotland and Ireland. COMMON CROSSBILL (Loxia c. curvirostra). Fluctuating, but on the whole marked increase, mainly due to immigration from the continent of Europe
and the recent planting of conifers. The Scottish Crossbill (Loxia c. scotica) also fluctuates. BRITISH CHAFFINCH (Fringilla Calebs gengleri). Spreading in woods in northern Scotland. CORN-BUNTING (Emberiza calandra). Marked ' decrease reported in Sussex, Essex, Suffolk, the Clyde and Tay basins, and some Scottish islands, and suspected decrease elsewhere. Hence probable general decrease. Cause unknown. CIRL BUNTING (Emberiza c. cirlus). Possibly only colonized England at end of 18th century as White did not observe it at Selborne and it was first met with by Montagu in S. Devon in 1806, During the 19th century, it was occasionally found nesting as far north as Yorkshire, but does not now extend beyond the Midlands. On the other hand there is some evidence of increase in southern England. HOUSE-SPARROW (Passer d. domesticus). Huge increase in Scotland and Ireland ; in England the bulk- of a similar increase probably occurred before 19th century. Decrease in towns in 20th century owing to replacement of horses by motors. TREE-SPARROW (Passer m. montanus). Colonies are local and fluctuate markedly for unknown reasons. WOOD-LARK (Lullula a. arborea). Marked decrease southern England and Ireland and complete disappearance from northern England. Certainly assisted by decrease in waste land and, till recently, by bird-catching. YELLOW WAGTAIL (Motacilla flava flavissima). Decrease in Scotland and Ireland and complete disappearance from some localities where it formerly nested. In both countries during last 100 years its distribution has been almost confined to limited isolated areas suggesting that it may formerly have been more widespread. In Northumberland it became very rare during 19th century, but has increased during last 20 years. BLUE-HEADED WAGTAIL (Motacilla f. flava). Perhaps increasing somewhat in S.E. England, but very local and perhaps overlooked earlier. (To be continued).