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Home , Black kite, Booted eagle, Booted eagles, Harrier (bird), Hen harrier, List of birds of Corsica

Changes in the status of of prey in By I. J. Ferguson-Lees

(Plates 21-26)

INTRODUCTION THIS PAPER SETS OUT to review, in the broadest terms, the present breeding status of diurnal birds of prey in Europe and the factors which have brought about increases or decreases during the last century; it •excludes the because too little is known about many of them. It is based on an extensive survey of the literature and forms part of a wider study concerned with status changes in all groups of European birds. Many generalisations can be made only after consulting a •considerable number of references and to cite the relevant ones in support of each point would make the whole unnecessarily tedious. For this reason, and because it is hoped eventually to publish the wider survey elsewhere with full references, sources of information have been omitted. They can, however, be supplied to those interes­ ted in particular aspects. The paper also includes information based on first-hand experience in Spain, France, Fenno-Scandia, Bulgaria and Rumania in recent years, as well as data gathered from correspondents in many parts of Europe. This material is being published now as a background against which the effect of toxic chemicals on birds of prey may be assessed. The plates have been selected to bring out some of the points made in the discussion. The illustrated are chiefly ones which have not been published in British Birds during the last ten years and the reader is reminded that a considerable number of photographs of other birds of prey have appeared in that time—including Lammergeier, Bonelli's , Goshawk, , , Honey , , Eleonora's Falcon and Lesser Kestrel.* In addition, photographs of Buzzard and Hen are being reproduced in our next issue.

SUMMARY OF THE PRESENT SITUATION Excluding owls, thirteen (or just possibly fourteen) species of birds of prey breed in the British Isles, five or six of them being extremely rare and confined to one or two localities; another ten species have occurred as vagrants. In Europe as a whole, 39 species of diurnal birds of

*The scientific names of the birds of prey can be found in the appendix on page 148; those of other species are given in the text. 140 STATUS OF BIRDS OF PREY IN EUROPE prey breed, or 37 if one excludes Pallas's and the whose ranges only just touch the extreme south-east corner of European Russia and about whose status there is, in any case, con­ siderable doubt. Of these 37, two-thirds are resident and the remain­ der move south for the winter, chiefly to . This total is made up of four (Neophron, , Aegypius, Gypaetus), six (, Hieraetus), three (), three round-winged (), three kites (, Ulanus), one sea-eagle (Haliaetus), one honey buzzard (Pernis), four harriers (Circus), one harrier-eagle (), one osprey () and ten falcons (Falco). Of the 37, 20 have decreased markedly this century, five more probably have, nine are just holding their own (or have offset decreases by increases elsewhere) and only three have really increased. The decreases include all the vultures, all the eagles except Booted, two of the kites, Marsh and Montagu's Harriers (except in the Baltic area and central Europe), the round-winged hawks and most of the large falcons. Holding their own are the buzzards, the and the small falcons. Spreading are the Black Kite, the and the Red-footed Falcon. Only the Buzzard, Sparrowhawk, Goshawk, Peregrine and Kestrel are really widespread in almost all parts of Europe where the is suitable, though the is generally distributed, often in very small numbers, in mountainous regions. Seven other species have a fairly wide distribution on the Continent, however, without extending into the more northern parts and in some cases being scarce or absent in the extreme south or south-east. These are the Kite (common also in the south but absent from the extreme east), Black Kite, Honey Buzzard (fairly widespread also in Fenno-Scandia), (common also in the south), Montagu's Harrier, Short-toed Eagle and Hobby (everywhere except much of Britain and Scandinavia and the Mediterranean islands). The Rough-legged Buzzard, Gyr Falcon, and Hen Harrier are primarily birds of the extreme north, though the last extends to many areas in the northern half of the main mass of the Continent, from northern Spain and northern France eastwards. The Egyptian and Griffon Vultures and the Lesser Kestrel are essentially southern species, while the Black , Lammergeier and Imperial, Bonelli's and are confined to the south-west and south-east. In the south-east alone are the Levant Sparrowhawk, Long-legged Buzzard, Lanner and Saker, while the Spotted and Lesser Spotted Eagles, Pallid Harrier and Red-footed Falcon are primarily found in the eastern third of the Continent. The White-tailed Eagle is now missing from the western third, while the Osprey is confined to the north and east and the extreme south (with a great gap in between). The Black-winged Kite is found only in

141 BRITISH BIRDS western Iberia and Eleonora's Falcon only in the Mediterranean islands. In general, birds of prey are more numerous in the south of Europe than in the north. Iberia and the Balkans have the greatest number of species and only in these areas, except at times of passage, are they still really numerous. This particularly applies to the comparatively undeveloped regions of southern Spain and Greece.

INCREASES AND DECREASES The causes of the increases and decreases are very varied, but, with a few minor exceptions, are all brought about by man. Broadly speak­ ing, they may be divided under shooting and trapping, poisoning, modern hygiene, habitat destruction, adaptability, climate and inter­ specific competition, though very little is known about the effects of the last two of these.

Shooting and trapping Guns and traps have long been used senselessly against any with a hooked bill, but certain groups have come in for more than their fair share and in the cases of some species this has been a major factor in their continued decline—especially the eagles, , Marsh Harrier, Goshawk, Sparrowhawk, Osprey, Peregrine and Merlin. The Golden Eagle, for example, has been exterminated in many parts of Europe and is now successful only in the wilder , especially parts of Spain and Greece and the Swiss and Austrian , Locally within these areas it has increased, as it has done in Scotland this century: thus in Switzerland there are now 40-50 pairs where there were only 20-30 earlier in the century. Similarly, the White-tailed Eagle has been harried out of many parts of its European range just as it was driven out of Scotland in 1908. It appears now to have been exterminated in and (the westernmost 'black' areas on the Field Guide maps, apart from Iceland). There are less than 50 pairs left in Sweden and only about 25 pairs in Finland; in the latter part of the 19th century there used to be as many as 5 o pairs in Denmark, but- it was exterminated there by 1912 and only odd pairs have tried to breed since. Its strongholds in Europe are now the coasts of Norway (where there are something over 200 pairs), northern Russia (though it is declining in the more populated parts) and some regions in the Balkans (in Rumania, for instance, it is now protected as a 'National Monument'). It is still shot in many areas, however, and the general picture is one of steady decline. Many other examples could be given. The Red Kite was formerly widespread throughout western Europe, but was gradually extermi- 142 STATUS OF BIRDS OF PREY IN EUROPE nated in most of Britain and, more recently, in Norway and Denmark {where, however, there has been a single recolonisation); and man's campaign against it because of real or imaginary depredations on has now made it a local and not very numerous bird over most of the rest of its range. Marsh Harriers are still frequently shot, often largely because they are one of the easier birds of prey to kill and because they hunt in the same areas as wildfowlers. The Goshawk formerly bred in Britain (and may now do so again in one or two localities), but this, like the Sparrowhawk, has always been a primary target of the game preserver and it is now a scarce bird nearly every­ where throughout its wide range. The discontinuous breeding range of the Osprey (which used, for example, to nest in Denmark) and the absence or scarceness of the Peregrine on many suitable cliffs are further tributes to man's prowess with the gun.

Poisoning Poisoning can be divided under two separate headings—direct and indirect. Only the large, -eating eagles have suffered much from direct poisoning and, inevitably, this has again particularly affected the Golden and White-tailed. Fortunately, however, the practice of putting out poisoned carcases to kill eagles is not very widespread. What has had an indirect but much more serious effect in eastern Europe—especially Bulgaria, Rumania and possibly Russia— has been the custom of setting poisoned bait for Wolves {Cants lupus). All too often vultures or eagles find the bait first. This is considered to be the main reason for the extermination of the Lammergeier in the Carpathians in the mid-1930's (though it should be added that the Lammergeier is one of the first species of vulture to go when conditions are acting against the carrion feeders and it has now been driven out of the whole of Europe except for three areas of Spain, the southern Balkans and the larger Mediterranean islands). The other form of indirect poisoning—the accumulation of chlorinated hydrocarbons used as agricultural pesticides—is fully dealt with by Stanley Cramp in his paper on 'Toxic chemicals and birds of prey' elsewhere in this issue and, though it is now perhaps the greatest threat of all to many species, it need not be discussed here at any length. Fortunately, it does not yet seem to be a very large problem in those parts of southern Europe v/hich are the main strongholds of birds of prey today. One aspect not touched upon by Cramp does have to be mentioned, however, although at the moment we have no information at all about it. This concerns those species which migrate to Africa during the winter. Most of Europe's birds of prey are residents, but about a dozen are summer visitors. Among these, three falcons—the Lesser Kestrel, Red-footed Falcon and Hobby—are -feeders which in

143 BRITISH BIRDS winter specialise on locusts, large and swarming white ants. The use of pesticides against these and other in Africa may thus in time prove another nail in their coffins.

Modern hygiene At one time carrion and edible rubbish were more readily available than is now the case and modern sanitary requirements are bound to be affecting all the , especially the vultures and kites, but possibly also the harriers, buzzards and some of the eagles (notably the Golden and White-tailed yet again). Vultures in some areas appear to be on the decrease and this may well be because of a shortage of carcases. In the Cevennes Mountains, for example, dead livestock used to be dumped into ravines, but here and elsewhere the tendency is now to bury or burn. Vultures are very long-lived and, as the first effect of such a food shortage would be only to inhibit their already irregular breeding, it may be some time yet before the real picture emerges. Similarly, kites and Egyptian Vultures feed on the litter of rubbish and excrement in the vicinity of poorer habitations in southern Europe; here again, present-day education and sanitation are acting against these birds.

Habitat destruction Whereas most of the -nesting eagles and vultures and those falcons which breed on cliffs and moors live in areas which tend to remain reasonably unchanged, two groups have suffered much from alterations to their —those that breed in forests and those that are essentially connected with marshland, either for nesting or for feeding. Examples of the latter category are the Marsh Harrier (a marsh nester) and the Montagu's Harrier (a marsh feeder). Both have been seriously affected by drainage and cultivation in central and southern Europe, and it may be partly displacement of population in this way which caused their comparatively recent extension around the Baltic. In Denmark, for example, Montagu's Harrier first nested in 1901 and by 1946 was breeding in 97 places; similarly, in Sweden the population grew to 15 pairs within 30 years of colonisation in 1923. It may have been the same factors which produced the recolonisation of East Anglia by the Marsh Harrier in 1915. However, over Europe as a whole, there is a steady decline and only in and around the big deltas and similar areas are these birds in anything like their natural abundance, so that one can see as many as ten or twenty in the air at once. Among species which have been reduced by the felling of forests and natural are the Goshawk and Sparrowhawk and especially two eagles, the Spotted and Lesser Spotted. The Spotted Eagle is 144 STATUS OF BIRDS OF PREY IN EUROPE doubly affected in this way because it is essentially associated with open swampy forest and it feeds largely on , and water- edge ; as a result, it has been almost exterminated in central Europe and is getting exceedingly scarce in southern Russia. The also requires large areas of marshy meadows and primeval forest, and both its breeding range and numbers have much decreased. Only two species have been helped by the clearance of forest and the development of agricultural land. These, the Kestrel and the Pallid Harrier, are dealt with in the next section.

Adaptability Some species are more adaptable than others to disturbance or changes in habitat, food or climate. Among the larger falcons, for example, the Gyr and the Saker are seldom found away from wild and un­ inhabited country and they retreat before the advance of urbanisation. The Peregrine, on the other hand, continues to occupy traditional cliffs even though they have become crowded with holidaymakers at the top and the foot, and there are also many records of its nesting on old buildings in various parts of Europe as well as on skyscrapers in North American cities. The most adaptable falcon of all is, of course, the Kestrel which may be found anywhere from bare to the centre of cities, from mountains to flat cultivated land and from wood­ land to rocky coasts; it is primarily a small feeder, but it readily takes to insects, birds, reptiles, amphibians and even carrion. It is perhaps most numerous in cultivated areas and it is not surprising that it has increased this century in Russia and other parts of eastern Europe as a result of the clearance of forests and the development of agricultural land. Perhaps the best illustration of ecological adaptability is to be found in the harriers, however. It has already been mentioned that Marsh and Montagu's Harriers, both very much tied to marshland and moors, have generally decreased, except in the Baltic area. The Pallid Harrier, on the other hand, which is primarily a bird of dry and cornfields, has extended considerably to the north-west in the last hundred years following increased cultivation in Russia. It now nests in the Baltic states and in 1952 even bred in Sweden and north Germany. Yet even more impressive in this respect is the Hen Harrier. This is a much persecuted bird, but it is holding its own because it is the least specialised of all the harriers. Its habitat varies- from steppe country and moorland to reed-beds, while its food may be anything from and birds to insects and . Perhaps this is best realised from the fact that in America, where it is the only- harrier, it fills the ecological niches of all four European species.

145 BRITISH BIRDS Another species which is very resistant to disturbance and ready to exploit any food source is the Black Kite. For instance, many nests are destroyed around the mouth of the Guadalquivir in southern Spain and the breeding-success there must be very low. Yet, 30-50 Black Kites can almost always be seen over that part of the river. This is because thousands of fresh-water are killed by the salt water every day when the tide rises. The Black Kite is one of the three generally increasing species of birds of prey and, though its spread in northern Europe may possibly be connected with the increase in mean summer temperatures, its readiness to breed in a wide variety of conditions, and to replace clutches destroyed, seems likely to be a major factor. By contrast, there are other birds of prey whose range is very much limited (and which in several cases are actually decreasing) because they are rigid food specialists. A fish specialist like the Osprey does not come into this category because its prey is ubiquitous. The Short- toed Eagle, however, which is a specialist on and large , is becoming increasingly scarce where the population is dwindling through the ploughing up of heathlands and . An­ other food specialist, the Spotted Eagle, has already been mentioned under 'Habitat destruction' and also in this category come those species which are locally limited by food preferences. In this country the disappearance of the (Oryctolagus cunimlus), following the arrival of myxomatosis in 1953, had a disastrous effect on the Buzzards in many districts because they were slow to adapt from this their favourite food. On many parts of the Continent, however, the Buzzard is a vole-eater and there it was quite unaffected by the dis­ appearance of the Rabbit, It would be possible to give many other examples of this—the Golden Eagle in Sweden, for instance, is largely limited by the distribution of the Reindeer (Ratigifer tarandus)—-but this section must be concluded by a brief reference to the northern species (especially Rough-legged Buzzards, Gyr Falcons and various owls) which fluctuate according to the population of Lemmings (Lemmus lemmus) and other rodents. One year there may be a number of pairs, the next summer none.

Climate Although the northward extension of the Black Kite in eastern Europe may be linked with the slight increase in mean summer temperatures, increases and decreases among birds of prey clearly have little con­ nection with climatic changes. Climate must limit some species, however. The Lesser Kestrel is essentially a bird of warm open regions and so one would expect its northward limits to be fixed by humidity and temperature (it has been stated that it is showing signs of spreading north-west in eastern Europe, but in Bulgaria, for 146 STATUS OF BIRDS OF PREY IN EUROPE example, it is now less numerous than formerly indicated). On the other hand, another colonial-nesting, insect-eating falcon—the Red- footed—might seem to be equally limited, yet it has extended markedly north-westwards during the last century. It has spread in north­ west Russia until it now nests in east Finland, the Baltic states and east Prussia. In 1928 it bred in Sweden and it has become an increasingly regular visitor to Britain and Scandinavia in the last 25 years. The only true insect-eater in north-western Europe, apart from the Honey Buzzard which largely confines its attention to wasps and bees, is the Hobby. Some birds which take many large insects—the White {Ckonia ctcontd), Roller (Coracias garrulus) and (Upupa epops), for example—have been steadily declining in north-western Europe and this decrease has generally been linked with the tendency towards a more maritime climate resulting in wetter summers which are presumed to affect the insect population. The Hobby has cer­ tainly decreased in Britain and may be declining or withdrawing in Scandinavia and Finland. However, apart from being purely an aerial feeder, the Hobby is different from the other species mentioned is that it switches to feeding on birds, especially young Hirundines and Swifts {Apus apus), when it has young in the nest.

Interspecific competition Very little is known about interspecific competition so far as the diurnal birds of prey are concerned, but there is some evidence that it affects the harriers, the sparrowhawks and the larger falcons. The Marsh Harrier, for example, seems to have succeeded in ousting the Hen Harrier in one or two areas around the Baltic. Similarly, the Saker may compete with the Peregrine in open rocky country in central Europe and south Russia. Perhaps the best example, however, is the case of the two sparrowhawks. The Levant Sparrowhawk appears to be the more successful in south-east Europe, in that where it is present it alone occupies the open woodland and parkland, while the Sparrowhawk becomes confined to the mountain forests.

RELIC AND FRINGE POPULATIONS Several of Europe's birds of prey are fringe populations of African or Asian species, or else relics of birds which once had far wider distributions. The Long-legged Buzzard and Levant Sparrowhawk,. for example, are Asian and African species with fringes in the Balkans,, the Lanner is primarily African and the Griffon Vulture is really an Asiatic bird with a remnant population in southern Europe. In such circumstances, a species is more than usually vulnerable to any factors working against it. This may be the reason why, for example, the , which is an east and central Asian species with a relic

147 BRITISH BIRDS population in Spain and south-east Europe, is declining more rapidly •even than the Lammergeier. It may be part of the reason why the Hobby continues to decrease in south-east England, even though it is interfered with less now than it was thirty years ago. In this category, too, come Europe's two most mysterious species— the Black-winged Kite and Eleonora's Falcon. The Black-winged Kite is a cosmopolitan bird with populations or closely related species in Africa, and and also locally in America. In Europe it is confined to one or two small areas in Portugal and Spain and it is not even known if it breeds regularly. It is dependent on warm, dry conditions, plenty of small rodents and large insects, and wood-edges or flat, open country with scattered trees. This habitat is common in parts of Spain, yet it does not succeed in spreading. Eleonora's Falcon, on the other hand, is now a well documented bird whose breeding areas are sufficiently known for the total population to be put within such precise limits as 1,500-2,000 pairs; two hundred years ago there were probably more. It breeds on island cliffs between the •eastern Canaries and Cyprus, and nowhere else in the world; and it winters in Madagascar and the Mascarenes. Its patchy distribution, strange habits and peculiar breeding season make it almost unique. It arrives back in the Mediterranean in late April but does not nest before mid-July. Parties hunt together in the twilight, catching insects and, in autumn, migrant to feed their young.

Appendix— of prey which breed in Europe (Neophron percnopterus) White-tailed Eagle {Haliaetus albicilla) Griffon Vulture (Gyps fulvus) Pallas's Sea-Eagle (Haliaiius leucoryphus) Black Vulture (Aegypius monachits) Honey Buzzard (Pemis apivorus) Lammergeier (Gypaetus barbatus) Marsh Harrier (Circus aeruginosas) Golden Eagle (Aquila chrysaetos) Hen Harrier (Circus cyaneus) Imperial Eagle (Aquila heliaca) Pallid Harrier (Circus macrourus) Tawny Eagle (Aquila rapax) Montagu's Harrier (Circus pygargus) Spotted Eagle (Aquila clangd) Short-toed Eagle (Circaetus gallicus) Lesser Spotted Eagle (Aquila pomarind) Osprey (Pandion haliaetus) Bonelli's Eagle (Hieraltus fasciatus) Hobby (Falco subbuteo) (Hieraetus pennatus) Peregrine (Falco peregrinus) Buzzard (Buteo buteo) Lanner (Falco biarmicus) Rough-legged Buzzard (Buteo lagopus) Saker (Falco cherrug) Long-legged Buzzard (Buteo rufinus) Gyr Falcon {Falco rusticolus) Sparrowhawk (Accipiter nisus) Eleonora's Falcon (Falco eleonorae) Levant Sparrowhawk (Accipiter brevipes) Merlin (Falco columbarius) Goshawk (Accipiter gentilis) Red-footed Falcon (Falco vespertinus) Kite (Milvus milvus) Lesser Kestrel (Falco naumanni) Black Kite (Milvus migrans) Kestrel (Falco tinnunculus) Black-winged Kite (Elattus caeruleus)

148 €F'i

PLATE 2 3 . Two bird- and insect-eaters: the Sparrowhawk {Accipiter nisus), much reduced by and woodland clearance, and now disappearing wherever toxic chemicals are used (page 125); and the Hobby (Fako subbiiteo), widespread in Europe but with only a tiny fringe population in England (page 147) {photos: Eric Hosking) PLATE 24. Two eagles: the Golden Eagle {Aquila chrysaUos), reduced in most countries by shooting and poisoning (page 142); and the Lesser Spotted Eagle (Aquila pomartna), a small-billed specialist on voles, frogs and lizards, decreasing with the clearance of swampy meadows and old forests (page 145) {photos: Eric Hosking) • 111** i

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