THE PROBLEM OF BIRDS ESCAPING FROM CAPTIVITY

Transcription

1 THE PROBLEM OF BIRDS ESCAPING FROM CAPTIVITY By DEREK GOODWIN THE acceptance or rejection of rarities and new candidates for the British list is often made difficult by the possibility of their being escapes from captivity. In many cases a certain decision is impossible and the only practical course is to take into consideration all the evidence and decide for the likeliest hypothesis. This article is written principally in the hope of giving assistance in this respect. Secondarily, it will, I hope, stimulate bird-watchers to identify and observe even those species which are obvious escapes. The behaviour and adaptability, or lack of it, of birds which thus find themselves far from their normal range and often far from any suitable environment, is of the utmost interest. continued

2 340 BRITISH BIRDS [VOL. XUX It would take too long to discuss all the species which have been imported and sold in this country during the past ten years. It must be remembered, therefore, that the birds dealt with in this paper are in the main only those which have been, and in many cases still are being, imported into this country in some quantities. Also, the numbers of the different species imported may fluctuate widely in response to trade, politics and other factors. Probably by the time this appears in print some species not even mentioned herein will be on sale in thousands and some now to be found in every bird-dealer's will no longer be obtainable. In assessing which birds have been most commonly imported since the war I have relied very largely on dealers' advertisements appearing in Cage Birds and other journals. One possible source of error here is that birds readily sold may be advertised only once whereas a like number of some less popular or more expensive species might be "on sale" for a considerable period. As an example of this the "pet department" of a certain London store had the same pair of Bronzewing Pigeons (Phaps calcoptera) "on sale" for about four years in the 1930s. In most cases, however, I think I have made a fairly accurate guess at the state of affairs. No attempt has been made to gather statistics of the numbers involved. In the more abundantly imported species such as many of the small African or Asian seed-eating Passerines it must run into very many hundreds, and more probably thousands, of each species in the course of a year. COUNTRIES OF ORIGIN The Budgerigar (Melopsittacus undulatus), Bengalese Finch (Munia striata, domestic form), Zebra Finch (Poephila guttata) and Diamond Dove (Geopelia cuneata) are now domesticated and the majority sold are bred in this country. In some other species, especially in some of the parrots, breeding accounts for a large proportion of the specimens extant in this country. Most foreign birds offered for sale are, however, wild-caught specimens. The main exporting countries or at least the regions whence the birds originate are India, West Africa, South America (probably Brazil), Central America (? Mexico) and' the Indo-Malayan region. Australia and southern Africa (? Portuguese East Africa) contribute to a somewhat less extent. (Many of the Australian seedeaters are fairly easy to breed in warm climates, where termites can be obtained ad. lib, and many of those appearing on the markets are, I understand, captive-bred specimens from South Africa.) Weaver-finches (Ploceidae). GROUPS AND SPECIES IMPORTED Weavers, whydahs, waxbills, munias and grassfinches of various species are imported in considerable numbers. None of them is at

3 VOL. XLIX] THE PROBLEM OF ESCAPES 341 all likely to reach Britain unaided. In many, either both sexes or the males in breeding plumage are strikingly coloured. None closely resemble any European species. Nevertheless, I know of a case where three bird-watchers field-guide in hand misidentified escaped Avadavats (Amandava aman&ama) as Scarlet Grosbeaks (Carpodacus erythrinus)! The true sparrows are seldom imported with the exception of the Golden Sparrow (Passer luteus) which has been widely offered for sale. In its yellow, brown, and chestnut plumage it might at first glance be mistaken for one of the vagrant buntings. Finches and buntings (FringiUidae and Emberizidae). Now that it is illegal to sell British birds, other than closeringed, captive-bred specimens, the European races of the Bullfinch (Pyrrhula pyrrhula) are no longer imported and sold in numbers, as was formerly the case. Many foreign finches are, however, commonly on sale, although their numbers, in species and individuals, are less than those of the weaver-finches. Some are quite distinctive, but others of this group are the most apt of any to cause confusion. Some of the African canaries (Serinus spp.), including the abundantly imported Green Singing Finch (S. mozambicus) are very like the Serin (S. canarius serinus) in general appearance and mannerisms. Hence it is important to notice the markings of any strange greenish or yellowish finch in some detail before coming to conclusions as to its identity (see discussion on page ). The Common Rosefinch or Scarlet Grosbeak (Carpodacus erythrinus) has been imported, and presumably sold, in large numbers. Some of its occurrences in Britain of recent years should, therefore, be viewed with suspicion. Of the true buntings (Emberiza and allied genera) only the Red-headed Bunting (E. bruniceps) has been, and is, imported and sold in any appreciable numbers. The bird is usually sold under the dealers' name of "Indian Yellow Bunting" or simply as "Yellow Bunting". The price asked is less than that for most foreign birds and much lower than that of any British finches with comparably bright plumage. This fact and the large numbers involved make it almost certain that birds of this species will in many cases have been bought by people with no real or lasting interest in bird-keeping. Such people are particularly likely to let their birds escape through carelessness or to tire of and liberate them. Judging by the number of recorded occurrences of this species in recent years some such factor seems likely to have been at work. Some of the American "buntings" (Passerina spp.) are imported and sold, seldom in very large numbers. These brilliant finches are hardly to be confused with any species that might get here by its own efforts. The breeding of finch hybrids, between different species of European finches or, more commonly between one of these and a

4 342 BRITISH BIRDS [VOL. XLIX domestic Canary (S. c. canarius), is popular with many birdkeepers. Such hybrids usually show their parentage fairly obviously (those with the Canary usually inherit indications of the streaked mantle and yellowish rump and belly of a wild Canary, rather than a clear yellow colour) but are often puzzling to the uninitiated. As they are often extremely hardy, with the wild parent's initiative but the canary's tarneness in the matter of coming to widows or bird-tables for food, they sometimes survive considerable periods at liberty. I was recently shown a photograph of a bird which was associating with wild Greenfinches (Chloris chloris) and had puzzled several bird-watchers. It was a Goldfinch-Canary hybrid. Timaliidae. Several species of this group are imported. Since most of them come from the Himalayan regions and are non-migratory, or nearly so, they are never likely to occur here except as escapes. Most commonly imported is the Pekin Robin (Leiothrix lutea) of which dealers have had large numbers in recent years. In the past many attempts have been made to introduce this most attractive species, but without permanent success. Escaped or liberated birds have often survived for long periods and even reared young. Blue-winged Sivas (Siva cyanea) and Silver-eared Mesias (Mesia argentigula) have been imported in much smaller numbers. Several of the Laughing-thrushes (Garrulax spp.) have been on sale. The dealer's name "Jay-thrushes" gives a good impression of what Laughing-thrushes look like in shape and stance, though they are weaker-winged and keep more to cover than either thrushes or jays. With the exception of the Pekin Robin, none of these birds seems to be imported in any quantity. Starlings (Sturnidae). The Hill Mynah (Eulabes religiosa) is commonly imported. These big black arboreal starlings, with their orange legs and bills and yellow head skin, are quite unmistakeable. Vast numbers of young are taken from the nest and hand-reared, there being a considerable trade in them not only to Britain and Europe but to America and the Far East as well. Their tarneness and powers of mimicry are well-known, but the "wolf-whistle" appears to be an innate note. A few Bank Mynahs (Acridotheres gingianus) have been imported since the war, as must at least one House Mynah (A, tristis) an escaped specimen of which lived for about four years in central London. The Rosy Starling (Pastor roseas) has been often on sale. Some of the African glossy starlings (Lamprocolius and Spreo spp.) are quite commonly imported and as they often breed well in captivity, English-bred specimens are sometimes on sale. Thrashes and chats (Turdidae). Of the more typical thrushes the only species frequently imported

5 VOL. XLIX] THE PROBLEM OF ESCAPES 343 and sold is the Orange-headed Ground Thrush (Geokichla citrina). More than one of these handsome slate-grey and rufous-orange thrushes have escaped and been at large for some time in recent years. American Robins (Turdus migratorius), some of the rock thrushes (Monticola spp.) and Blue Whistling-thrushes /(Myiophoneus caeruleus) are sometimes on sale, but in small numbers. Of the smaller birds of this family the Shamah (Kittacincla macroura) and the Magpie-robin (Copsychus saularis) are the only ones commonly on sale. Other small Passerines. Several species of bulbuls (Pycnonotidae) are fairly frequently imported, as are the more brightly coloured fruitsuckers (Chloropsis spp.). Of the Icteridae some of the hangnests or troupials (Icterus spp.) are sold, though not in large numbers. Others of this group are also on sale from time to time. Tanagers (Thraupidae) in some numbers and a few honey-creepers (Coeribidae) and humming birds (Trochilidae) are sometimes on sale. Of other birds that may turn up from time to time the only one worth mentioning is the Yellow Wagtail (Motacilla flava). Quite a number of "Indian Blue-headed Wagtails" have been offered for sale. All the evidence suggests that these birds did in fact come from India, and so more than one race occurring only rarely in Britain might have been involved. The possibility of Yellow-headed Wagtails (M. citreola) being among such consignments cannot be excluded. Crows, pies, jays, etc. (Corvidae). Relatively few of these are imported. Blue Magpies (Urocissa), Green Magpies (Cissa chinensis), the Wandering Tree-pie (Dendrocitta vagabunda), the Lanceolated Jay (Garrulus lanceolatus) and some of the South and central American jays are not infrequently on sale. The numbers involved are small, however, although as these birds tend to be long-lived, expensive and do not sell very freely, more may appear to be in the country than is actually the case. None of them can be mistaken for any species likely to occur naturally. Pigeons and doves (Columbidae). Many species are imported and sold. Shortly after the war some dealers were offering Collared Turtle Doves (Streptopelia decaocto (see discussion on page 346). More recently quite a number of Speckled Pigeons [Columba guinea), Red-eyed Doves (S. semitorquota), Spotted Doves (5. chinensis) Crested Pigeons (Ocyphaps lophotes), and Masked Doves (Oena capensis) have been on sale. Other species have been offered in smaller numbers, the common dealer's practice of inventing euphemistic names for the less colourful birds often making it difficult to decide from the advertisements exactly what species is involved.

6 344 BRITISH BIRDS [VOL. XLIX Parrots, parrakeets, lovebirds, etc. (Psittacidae). Great numbers of these were imported during the brief interval that the "parrot ban" was lifted. None of them is likely to get to Britain unaided nor would even the most eager rarity-hunter claim the Budgerigar seen on his lawn as a wind-drifted migrant from Australia. Ducks, geese, etc. (Anatidae). The keeping of birds of this group is popular and fashionable, being looked on with favour even by many who consider the keeping of wild birds of other families reprehensible. Possibly this is because it is common to mutilate them so as to prevent their ever flying again and then to let them wander in a garden, park or other large enclosure where they appear "free" to the uninitiated. It is, however, becoming increasingly the practice to leave the young of such birds intact and at full liberty. Whether from the standpoint of aesthetics, humanitarianism, or scientific study, this is to be highly commended but it inevitably casts suspicion on records of such species as Ruddy Shelduck (Casarca ferruginea) or Red-crested Pochard (Netta rufina). In this way the Mandarin Duck (Aix galericulata) has for some years become established in a wild state in parts of Surrey, Berkshire and elsewhere, and it still seems to be maintaining its numbers in spite of persecution by man. Various other species of foreign ducks are often locally, and usually temporarily, to be seen in a feral state, and all records of species known to be commonly kept must be highly suspect. Game-birds (Phasianidae). Game-birds of many species are imported from time to time and some pheasants, such as the Golden (Chrysolophus pictus), Amherst (C. amherstiae), Reeve's (Syrtnaticus reevesi) and various kaleeges (Gennaeus spp.), are bred in fairly large numbers in captivity. Attempts have been made to establish many of them in Britain but have usually met with only local or temporary success, owing to the unceasing persecution from shooters which gamebirds undergo in Britain. The only game-bird confusable with a species liable to occur here naturally is the Rain Quail (Coturnix coromandelicus). This species has been imported and offered for sale occasionally in the past three or four years. It is extremely similar to the common Quail (Coturnix coturnix) in size and colouration, but in the hand can be at once distinguished by the plain unbarred outer webs of the primaries. Its call is also said to differ. Serins and ring-necked doves. In view of the westward extension of range of the Serin (Serinus canarius serinus) and the Collared Turtle Dove

7 VOL. XLIX] THE PROBLEM OF ESCAPES 345 (Streptopelia decaocto) and the importance of recording their arrival in any new localities it seems advisable to mention rather fully the means by which they can be distinguished from allied species frequently kept in captivity. Of the many species of canaries (Serinns spp.) found in Africa the one that is imported and sold in large numbers is the one most easily confused with the Serin. This is the Green Singing Finch (S. mozambicus). The male Green Singing Finch can be told from the male Serin by its having a clearly defined pattern in grey and yellow on the face, brighter yellow unstreaked under-parts, and an unforked tail (see Fig. i). There are other minor differences and it is altogether a brighter-looking bird. The female is duller than the male (and hence more easily taken for a Serin), has the flanks and sides of the breast heavily suffused with olive green and a usually conspicuous pectoral band of dusky spots. Juveniles resemble the female but are paler and browner with conspicuous yellowish-buff edgings to the wing feathers. The description applies to the race usually imported, which is 5. mozambicus caniceps. Other races vary slightly in size and colour, but except that in some the dark areas of the male's head are greenish or olive rather than grey, these differences do not invalidate the above distinctions. FIG. I SERIN (Serinus canarius serinus) (left) AND GREEN SINGING FINCH (Serinus mozambicus) (right) This sketch is to show the clearly defined head-pattern, unstreaked under-parts and unforked tail of the Green Singing Finch, which may otherwise be mistaken for the Serin. The European race of the Serin is not commonly, if at all, imported, so there is no reason to suspect the status of individuals seen. Recently some specimens of the Atlantic islands race (S. c. canarius), the ancestor of the domestic Canary have been exhibited at the London Zoo and it is possible that others may have found their way to bird-dealers' establishments. This bird is larger and has a longer tail than the European form, but otherwise much resembles it. Although some years ago more than one dealer was advertising

8 346 BRITISH BIRDS [VOL. XLIX "Indian Ring Doves", S. decaocto does not seem to have been imported since. As it is a rather sombrely coloured dove it is, however, likely that dealers would invent some euphemistic title for it, in some cases, rather than offer it under a recognizable name. The bird most commonly mistaken for decaocto is the Barbary Dove (which although given a scientific name of its own S. risoria is almost certainly the same species), which is at once recognizable by its pale buffish fawn or creamy colour in contrast to the greyish fawn with blackish primaries of the wild form. Some other ring-necked doves which are, or might be imported require more care. The Red-eyed Dove (S. semitorquata) has dark greyish-brown upper-parts, grey forehead, dull wine-red breast and belly and the tail patterned in blackish and grey with no white. The Cape Ring Dove (S. capicola) is very similar to decaocto in general appearance, but has a black streak from the corner of the mouth to the eye, as has the much smaller (smaller than a Turtle Dove) and more brightly coloured Vinaceous Dove (S. vinacea). The Mourning Ring Dove (S. decipiens) is darker than decaocto, being intermediate in colouration between it and semitorquata but with the tail pattern nearer to decaocto. However, this species seems to be very seldom imported and I have never seen one in this country, so there is probably not much need to worry about it. The female of the Red Ring Dove (S. tranquebarica) can at once be told by its small size, dull drab brown plumage and short tail. The male is dull pink with blue grey head and rump. Behaviour of escaped birds. Birds that are lost and starving may perch or seek food in unusual situations or show an indifference to the presence of man or other enemies. This behaviour is not, of itself, proof of their having escaped from captivity, since vagrant wild birds may be in like condition. Relative wildness or tameness towards man may not be a clue to origin. If a bird deliberately tries to attract a man's attention, going towards (even though it may be afraid to go very near) and looking eagerly into his face, perhaps uttering a begging call, then it is quite certain that it is accustomed to being fed. From its species and probable country of origin it will usually be possible to know whether it is likely to have been fed in a wild state by man, or whether such behaviour probably indicates an ex-captive. Lack of fear of man in a healthy bird of a species known to fear him in most of its range would point to its being an escape, but similar "tameness" in, say, a Laughing Dove (Streptopelia senegalensis) or a Waxwing (BombyciUa garrulus) would be of no significance. Fear of man is of no value whatsoever for an opposite conclusion. Even tame individuals may regain all their former timidity when they find themselves at liberty in a strange area. Contrary to popular opinion, birds bred

9 VOL. XLIX] THE PROBLEM OF ESCAPES 347 in captivity are seldom tamer than wild-caught ones, unless they have been taken from their parents at an early age and reared by hand. Escaped birds, particularly if in good health, tend to> find and establish themselves in the nearest approach to their natural environment. This may seem self-evident but it needs emphasizing as I have twice heard experienced bird-watchers express surprise because escaped foreign bird were in the "right sort" of habitat. It would indeed be more strange if they did not seek out the "next best thing" to their normal biotope. Here of course one must try to take a literal "bird's eye view" and remember that the essential features of the habitat as they appeal to the bird may not be those that at first appear as such to the bird-watcher. That a bird may turn up far from the nearest known dealer or bird-keeper is no proof of wild origin. Nor, as was implied in a discussion on the validity of a certain species, are bird-dealers and bird-keepers confined to London and eastern England. Random wanderings or attempts to perform their normal migratory movements may well be undertaken by escapes. A Barbary Dove that, after being at liberty for the whole four months of its life, vanished from my garden, was found alive and unharmed on the doorstep of the Tuskar Rock lighthouse in Ireland some two weeks after disappearing from Virginia Water, Surrey. Presumably it had crosed the Irish Sea unaided (since being handtame, as birds of this long domesticated species almost always are, it would almost certainly have gone to someone for food and been caught had it settled on board a ship) and had it not been wearing a name-and-address ring no one would have supposed it to have come from further than the nearest keeper of these birds in Ireland. Condition of escaped birds. There is a widespread opinion, fostered by many nature-journalists, that captive birds are invariably inferior to their firee relatives in health and plumage condition. Unfortunately, whilst a gross libel on the majority of serious aviculturists, this is not without some foundation of truth. The proprietors of some petshops and some Zoological gardens appear unable or unwilling to give the birds in their charge proper food and individual attention. It is just from the unhappy results of such mismanagement that the general public, not unnaturally, form their opinion of birds in captivity. In the case of most species of birds that are commonly kept (the exceptions will be mentioned shortly) present-day knowledge of their requirements is such that it is quite possible for captive specimens to be fully equal in plumage and soft-part colouration to those at liberty. The fact that a bird is in perfect plumage cannot then, of itself, be any evidence against its having escaped. On the other hand certain imperfections of plumage may point

10 348 BRITISH BIRDS [VOL. XLIX very strongly to recent captivity. Birds in cages, and to a lesser extent those in aviaries, are very apt to break their wing and tail quills. If a bird has several broken wing- and tail-feathers the odds are very strongly in favour of its being an escape. Of course, confinement for anything more than a few minutes in a trap may produce the same result. For this, apart from other reasons, the practice of some ringers, in the past at any rate, of leaving the first bird caught in a multiple potter trap as "bait" for Sparrowhawks (Accipiter nisus) is thoroughly reprehensible. There are two exceptions to the general rule that many broken wing- and tail-quills are a sign of the bird's having battered about in a cage. Firstly, under modern conditions hole-nesting birds may nest in sites where they break their wing quills getting to and from the nest. This occurs in my district with chimney-nesting Jackdaws FIG. 2 To snow DIFFERENCES IN FEATHER-BREAKAGE AS A RESULT OF CAPTIVITY (left) AND " FRETMARKING " (right) Uneven breakage, as shown on the left, is typical of that found in caged birds ; where "fretmarking" has occurred (for explanation see text), all the wing-quills are usually broken at the same point. (Corvus monedula), some of whom when feeding young are so impeded by their shortened wings that they can hardly fly. In these, however, the tail-feathers are seldom broken and their front claws are invariably worn down to the quick with the constant climbing up the chimney. Secondly, temporary starvation or some other physical disaster at the time of feathergrowth may cause a "fretmark" or "hunger-bar" on the growing feathers (see Fig. 2). These are particularly common in the juvenile feathers of the larger species of nidiculous birds. Feathers are very liable to break at the fretmark. In the case of a juvenile

11 VOL. XLIX] THE PROBLEM OF ESCAPES 349 all the wing and tail quills will usually be fretmarked at the same point. The breakage of each feather renders its neighbours more vulnerable to injury and a badly fret-marked juvenile may, in after life, lose all its wing- and tail-quills through their breaking off at a fretmark. Birds that keep much to cover such as Jays may live in this condition for some time, but, since their foraging powers are severely restricted, they are likely to go from bad to worse in any subsequent moult. Such a condition can also arise in captivity and so is no indication either way. To sum up: If a bird has many broken wing- and tail-quills it is usually an ex-captive. If it has only one or two broken quills or if all or most of the wing- and tail-quills have broken at the same point and any that have not are fret-marked at this point the bird is just as likely to be truly wild. Linnets (Carduelis cannabina), Redpolls (Carduelis flammea), crossbills (Loxia spp.) and rosefinches (Carpodacus and allied genera) usually lose their red colours after moulting in captivity (and captive-bred specimens seldom attain them), these being replaced by a dull golden tinge. The exact reasons for this are as yet obscure and further complicated by the fact that occasionally wild birds may be found of the typical "captive" colouration, that there are records of some captive birds showing the normal red colours, and that captive birds in their usually duller dress will breed readily and successfully. Lack of the normal red colour in an adult male of any species belonging to the above-mentioned groups would be strong corroborative evidence though not in itself proof of the bird being an ex-captive. Plumage that is dirty or duller and/or paler than normal frequently results from improper conditions of captivity. It is of little positive value in this connection, however, since sickness, hunger or ill-health may induce a similar state in wild individuals. The same is true of abnormally pale soft-parts. This particularly seems due to bad feeding. Most people must have noticed how often gulls, and in other countries Black Kites (Milvus migrans), that are feeding principally on waste human food have much paler and dingier legs and bills than those of their species that are living on natural foods. Hawks and falcons in Zoos often have pale creamy legs that would be brilliant yellow in a well-fed wild specimen. Gross overgrowth of claws and mandibles sometimes occurs in captive birds, often if they are confined in cages or aviaries with only hard floors and perches. This seems to occur only very rarely in truly wild birds (though overgrowth of the upper mandible is a common pathological condition in feral pigeons living in towns) and in the case of any bird showing it to a marked degree there would be an added reason for presuming it to be an escape unless there was some very strong contrary evidence.