Introduction Paper presented at Annual New Year's Meeting Bird Conservation Society of Thailand, 9 January 2000, Bangkok

In December 1987 , at the National Wildlife Seminar, Kasetsart University, I gave a talk entitled “New Species of Birds in Thailand, 1974–1987. So I am honoured that, 12 years later, BCST should ask me for a similar talk. I use this as an opportunity to give an update and also to compare the pattern of addition of new records between the two periods. A new checklist of Thai birds for BCST is currently in preparation, so those of you who want more information should wait to refer to this.

In preparing this summary, I have excluded some records which are problematical. Preliminary indications are that at least three full species in the Herring Gull complex have been recorded in Thailand, but since the taxonomy and identification of these forms is still confused I have chosen to omit them from this summary. Some other records included in this summary still await confirmation by the observers concerned.

I have taken the year 1989 as the start date for this review, since the text for Guide to the Birds of Thailand was written by then. So we have a period of 11 years, 1989–1999 to consider, compared with 14 years for the earlier review.

The two periods are not strictly comparable in some ways. In particular, the second period has been a very dynamic period for taxonomic research. 1990 saw the publication of Sibley and Monroe's new checklist, which constructed a much revised phylogeny based on DNA-DNA hybridization data (Sibley and Monroe 1990). The Sibley and Monroe listing has been followed by most new field guides, including Grimmett et al. (1998) and Robson (2000) and of course is the basis for the sequence followed in annotated checklist of birds of the Oriental Region (Inskipp et al., 1996). Contra popular belief, though, the Sibley work did little to reveal detailed relationships within genera. Sibley was mostly reliant on secondary sources for most of the splits he adopted, but further biochemical research and field studies has substantiated many of these, and in addition has added some others.

In terms of taxonomy , the first half of the twentieth century was a period of amalgamation. Some retrenchment was necessary to redress the balance and cope with the plethora of new forms described by nineteenth century museum workers seemingly obsessed with minor variations. During this process, many previously described species were united or downgraded to subspecies. Much of this ‘lumping' was justified, but inevitably a lot of previously described “good” species disappeared.

The trend now , as birds are known not only by museum skins, but by their behaviour and habitat is for many of these forms to be once again elevated to species level.

Since 1980 , previously inaccessible areas in Asia have opened up to renewed ornithological exploration, and the present generation of field workers, armed with sophisticated photographic and sound-recording gear have enlarged our understanding of bird distribution, behaviour and taxonomy. Recent fieldwork, particularly in China, the breeding grounds for many of our winter visitors, has revealed previously suspected or unsuspected complexes of sibling species which has major implications for the Thai faunal listing. Birds may sing completely different songs on breeding grounds, where they behave as good species, but their plumage differences as so minor as to be virtually undetectable in the field. Some of the biochemical work within genera has revealed that forms previously thought to be each others' closest relatives are not so. One example is that of the Manchurian Reed Warbler Acrocephalus tangorum, sometimes treated as a subspecies of Paddyfield Warbler A. agricola (e.g., Lekagul & Round 1991; Alstr?m et al., 1991). In fact DNA phylogeny not only shows that it is a good species, but that its closest relative is Blunt-winged Warbler A. concinens , not Paddyfield Warbler as previously thought (Leisler et al. 1997).

» The new Thai birds

I provisionally list a total of 46 “new” species of bird since Guide to the Birds of Thailand, including the three species (Pied Avocet, Malaysian Blue Flycatcher and Brambling) which are listed in Appendix 1. Of these, we can immediately say that 36 result from new discoveries in the field; one Western Marsh Harrier is derived from previously overlooked museum specimens; and nine are added from taxonomic splits.

» Taxonomic splits :

Of these nine taxonomic splits , seven (Striated vs. Red-rumped Swallows, Brown-rumped vs. Rosy Minivet, (resident) Blue-throated vs. (migratory) Chinese Blue Flycatcher, Manchurian vs. Paddyfield Warblers, Lemon-rumped vs. Pallas's Leaf Warblers, Hume's Leaf Warbler vs. Yellow-browed Warbler; and (resident) Paddyfield vs. (migratory) Richard's Pipit were all forms previously known for Thailand, but treated as subspecies.

The two new full “taxonomic species” are both members of the Golden-spectacled Warbler complex, the subject of a paper by Alstrom and Olsson (1999). They describe five definite species, three of which are known to occur in Thailand in winter (though ongoing biochemical work suggests there may be as many as seven species in the complex).

I have handled and banded all three of the Thai forms, which have different calls and different tail patterns (the tail pattern is not discernible in the field). Two of these forms can be found wintering in Khao Yai: Grey-crowned Warbler S. tephrocephalus (which calls tup) is found at higher elevations (and is the common form in both lowlands and mountains in northern Thailand) while Plain-tailed Warbler S. soror is the common form around Khao Yai HQ, and the form which occurs in mangroves around Bangkok on migration. It calls with a truncated Greenish Warbler-like note, tsrit. The third form, Bianchi's Warbler S. valentini has a whistled call. This seems to be the scarcest form in Thailand: I have netted and banded one bird on Doi Ang Khang and have seen it and taped its calls in Vietnam. If you listen to call-notes, you should be able to separate all three with care. All three of the Thai forms can be found on a single mountain in China, stacked one above the other, in different habitats and singing completely different songs. There is no question that these are perfectly good species.

Other difficult forms among the warblers are in the leaf-warblers. We have long recognised that we had two forms of the Lemon-rumped Leaf Warbler. However, this is now split into two species: Pallas's Leaf Warbler Phylloscopus proregulus, with a more northerly and easterly breeding distribution, and Lemon-rumped Warbler Phylloscopus chloronotus which breeds around the eastern and southern margins of the Tibetan Plateau. But to complicate the picture, we now find that the commonest form in Thailand is not chloronotus, as we previously thought, but Chinese Leaf Warbler Phylloscopus sichuanensis, which breeds in northern and western China. This was only recognised as a distinct species in 1992 (Alstr?m et al., 1992). In fact, chloronotus may be rather rare in Thailand: I have so far only found one museum specimen of chloronotus and even then, it is hard to be sure that it is chloronotus and not a fourth new species Phylloscopus kansuensis, described in Alstr?m et al. (1997). All these forms are very similar on plumage, but sing quite different songs and are fully isolated as breeding species. They are good species under the biological species concept.

» New discoveries :

The 36 new discoveries are broken down by region and by source area in Table 1. It is no surprise that migrant species dominate, contributing about two-thirds of the new birds. Perhaps it should be surprising, in view of Thailand's relatively well-explored state that as many as one third, 11 species, were resident.

We tend to concentrate on the northern mountains, where we hope to find new cold-weather visitors. But when the source area of the discoveries is considered, it is perhaps surprising that the north (11 new birds) was overtaken by the south (14 new birds) as the place of discovery for most new birds. And whereas all of the 11 species from the north were migrants, only 5 of those in the south were migrants. All of the new resident southern birds were from the extreme southern provinces of Yala and Narathiwat, mostly Hala-Bala. Of these, were 7 montane forms and only two were lowland forms. So altogether the south contributed 9 of the 11 new resident species.

Central Thailand continued to contribute many new species (7) as perhaps the most heavily watched part of the country.

In addition to the three species already listed in Appendix 1 of Lekagul & Round (1991) a further 18 of these new species were predicted to occur (Appendix 2). But it is surprising that many others of those which have appeared (8 migrants and 6 residents) were not predicted at all.

Perhaps the single most surprising addition to the Thai list in the past decade has been Ratchet-tailed Treepie, recorded in 1989 by Pinit Saengkaew, Santana Pluemshoosak and others from Kaeng Krachan. This moist forest species is otherwise restricted to the Annamite mountains in Laos, Vietnam and extreme southern China. Its appearance anywhere in Thailand, let alone the south-west, could not reasonably have been predicted. We are forced to conclude that it must one have been widespread and that, at some time in the past, its moist forest habitat must have been more widespread.

» Comparison between two periods

52 species were added during 14 years 1974–1987. These all resulted from new discoveries: none were added as a result of taxonomic revision. During 1974–1987 there was an average of 3.7 new discoveries per year, compared with 36 new discoveries in the past 11 years (nearly 3.2 new species per year). So the rate of new discoveries has hardly slowed between the two periods.

During 1974–1987, 41 of 52 new discoveries (79%) were migrants whereas during 1989–1999, 26 of 36 (72%) were migrants. This slight, but probably significant increase in the proportion of discoveries of residents is surprising and would certainly not have been predicted in 1987. Evidently, the Thai resident avifauna is richer than we thought.

When we examine our new birds by ecological grouping, we can see that the distribution is broadly similar between the two eras, with forest and open country landbirds contributing a roughly similar proportion to the whole in each. Waterfowl have continued to be well- represented among our new birds, but waders have dipped somewhat in the second period. There may be relatively few likely new ones left to add.

One major difference between the two periods is that in the first period, only 12 of 52 species (23.1%) were added by Thai birdwatchers. In the second period, while visiting westerners still made the larger contribution, at least 13 of 36 (36%) were first found by local Thai birdwatchers and professional wildlife biologists. This is indicative of the growing active involvement and increasing knowledge of the present generation of Thai birdwatchers.

» The future and future predictions

We have seen a lot of changes in Thailand over the past twenty years. We can certainly predict that additional species of birds will continue to be added to the Thai list as coverage improves. But most of these future discoveries will be migrants: the potential for adding further residents is a lot more limited. Forest birds seldom show dramatic range expansions: they are limited by the area of habitat they can occupy and forests in most places are shrinking due to continued human disturbance. But we will certainly add a few further resident species. Some forest birds may have been overlooked while we may perhaps expect some more open-country birds which may be expanding their ranges. In the past twenty years, we have been colonised by House Sparrow: some mynas seem to have expanded their ranges in the peninsula, and there is the potential for other, mainly sedentary species to follow. As I write, Thailand's first Crested Myna, a widespread open country species in the Oriental region, is probably still at Bang Poo. Does this herald the beginning of a colonisation by this species? The Collared Dove Streptopelia decaocto underwent a massive range expansion into Europe during the 1950s and 1960s. Hong Kong has just had its first records and we are wondering if this presages the beginning of a similar range expansion in Asia.

The situation is further complicated by the large ongoing trade in cagebirds. Large numbers of birds continue to be imported from China and elsewhere, and increasingly we have to ask ourselves whenever we see something unusual, whether it is a genuine vagrant, or whether it has just escaped from a nearby aviary. Several species already added to the Thai list, and thought on grounds of probability to be expected, genuine migrant visitors still have some traces of doubt attached to them. Among them we might number Baikal Teal and Mandarin Duck, both commonly kept in waterfowl collections; Milky Stork, Rose-coloured and Brahminy Starlings, and Black-headed Bunting as well as the above-mentioned Crested Myna.

» Gulls :

As already mentioned at least three forms of “herring gull” have been recorded in Thailand. There has also been a report of what might be Mew Gull Larus canus. Careful documentation and assessment of these records is necessary. Even the most knowledgeable gull-watchers are loath to categorically identify first winter birds which constitute the majority of ‘herring gulls” so far found in Thailand. detailed knowledge of individual, subspecific and specific variation is still inadequate.

» Skuas and other seabirds :

There have already been at least two reports of unidentified large skuas, probably South Polar Skua Catharacta maccormicki from both coasts. Although it is provisionally listed by Wells (1999) I have so far resisted the temptation to add this species to the Thai list because of the possibility of confusion with Antarctic Skua C. antarctica which has been recorded from south Indian waters.

The potential for adding new seabirds is very great but in order to do this observers will probably need to take passage on fishing boats or research vessels, traveling out to fishing grounds where upwellings may produce richer food supplies for pelagic birds and fishes. In addition, the return per unit effort in terms of numbers of individuals is likely to be very low: seabirds have proved extremely scarce on the few voyages so far undertaken.

» Shorebirds :

Of the shorebirds predicted to occur in Appendix 2 of Lekagul & Round (1991), we are still waiting for Lesser Yellowlegs and Pectoral Sandpiper. Thailand may already have had its first Eurasian Oystercatcher, but details received were insufficient. The first Eurasian Oystercatcher for Vietnam was discovered in the past couple of months.

» Forest birds :

It is possible that further exploration of the mountains in Hala-Bala will add one or two further montane birds. But otherwise, we are forced to conclude that there are few other resident forest birds left to discover in Thailand. Most of those predicted in Lekagul and Round (1991) were montane birds known from eastern and southern Burma (e.g., Red-tailed Minla, Greater Rufous-headed Parrotbill) have not yet been found. The chances of them being found in Thailand are very small, although there still are one or two unexplored high mountains in Western Thailand.

» Eastern flyway migrants :

Many other palearctic migrants winter to the east of us migrating through Japan, Taiwan and Philippines, including Middendorff's Grasshopper Warbler, Gray's Grasshopper Warbler and Pechora Pipit. It was surmised that we ought to receive occasional strays from this eastern flyway. So far, we have had Narcissus Flycatcher (not listed by Lekagul & Round (1991) because it was then treated as conspecific with Green-backed Flycatcher Ficedula elisae, long known to occur in Thailand; and, apparently, Grey-streaked Flycatcher Muscicapa griseisticta. The author has already made one brief sighting of what was probably Middendorff's Grasshopper Warbler, but the details noted were insufficient to justify adding it to the Thai list.

» Palearctic and Sino-Himalayan overshoots :

There are a number of migratory landbirds from the Palearctic and Sin-imalayan regions normally wintering to the north of us, but which might have the potential to occur here through overshooting their normal wintering ranges, perhaps in exceptionally cool weather. The recently added Merlin is from this group. I have heard rumours of Common Redpoll Carduelis flammea having been sighted in Thailand, though details have never been forthcoming. There are also potentially many thrushes which might occur.

» Taxonomic splits :

More species will almost certainly be added as a result of taxonomic splits. McGowan and Panchen (1994) have placed the forms of Kalij Pheasant in western Thailand as subspecies of Silver Pheasant, arguing that true Kalij are only to be found west of the Irrawaddy. While evidence of sympatry between Silver Pheasants and Kalij Pheasants in Thailand is difficult to substantiate, the Thai Kalij and Silvers seem to occupy completely different habitats and my suspicion is that they are distinct species. Our Thai Kalij might constitute a third, distinct species and my hope is that DNA work reportedly in progress will show this to be the case.

Black Kite is sometimes treated as two species, the migratory birds being separated as Black-eared Kite Milvus lineatus. Swiftlets are another highly problematical group. Our breeding Himalayan Swiftlets in western Thailand are sometimes placed as a separate species, Indochinese Swiftlet Aerodramus rogersi. What of the Large-billed Crow, Corvus macrorhynchos. Some authors split the Indo-Burmese population as Jungle Crow C. levaillantii, citing sympatry with Large-billed Crow in Northern India. Both forms occur in Thailand. Other interesting problems are posed by some of the bulbuls found in western Thailand. These will only be resolved when calls and other behavioural and biological information can be matched with morphology of the various forms.

Even the new generation of field guides are of little help in separating these more problematical species. The birdwatcher's identification task has generally become more difficult: it requires a lot more knowledge and sophistication to separate many forms previously lumped, but now recognised as good species. Along with this, I would hope that our ability to recognise and record distinctive subspecies will evolve further so that we can more fully document their geographical ranges and seasonal patterns of occurrence.

» Recording rarities :

Birdwatchers in Thailand have a long way to go in terms of recording descriptions of new birds. It is very rare for me to receive a description of a rarity which would be of a sufficient standard to pass a national rarities committee in Britain, Europe and USA. I actually am quite concerned that by drawing attention to a difficult species like Blyth's Pipit, the club will become deluged by claims of further sightings. Some might be genuine, but without adequate documentation, it will be very difficult to “separate the wheat from the chaff”. So more knowledge, restraint and self-discipline needs to be applied in recording Thai rarities and writing detailed field descriptions which record what you actually see, not what you think you ought to have seen.

» Photography and video :

One obvious tool that we have to assist us is much improved photographic and video gear, and means to share and display this information through use of computers. We \are now seeing some really world class photographs and video stills being produced by Thai birdwatchers and bird photographers which are making a major contribution to record documentation. It would be more or less impossible to even begin to sort of difficult groups, such as herring gulls, without good images. Bird photographers have a vital role to play in helping to document new species and I think ornithologists should cooperate with bird photographers as much as possible. It could also be argued that if bird photographers were to concentrate more on documenting migrants and strays, it would relieve some of the pressure on birds' nests. We have received many disturbing reports of birds apparently deserting their nests because of bad behaviour by bird photographers.

» Netting and ringing :

Netting and ringing are other techniques which should be more applied to study and recording birds in Thailand. Identification features, such as tail-patterns and wing formulae can usually only be discerned in the hand. Very little ringing is done in Thailand, and its present value is highly doubtful since identification standards ageing and sexing, moult recording, and other skills are low. On the one occasion when I was invited to join some organised ringing, I had to step in to prevent some common wintering Phylloscopus warblers being misidentified by the foreign scientists working with RFD. If ringing is to make a significant contribution to bird study, then there needs to be a role for the knowledgeable amateurs in BCST. RFD simply doesn't have enough skilled manpower to implement activities on a significant scale. The ringing schemes of Britain and Japan are among the oldest, largest and best organised in the world and in each case, amateurs working at weekends make the largest contribution to numbers of birds ringed.

» Publications :

Significant records should be put on record in the scientific literature. The unfortunate reality is that anything published in purely Thai language is will fail to receive appropriate worldwide recognition. Thai scientists usually seek to publish in English language journals, and birdwatchers should follow suit. Although Recent Reports of BCST Newsletter is widely consulted by scientific and museum ornithologists around the world (and is also now available on the Internet at the Worldtwitch web-site), as we make clear, records contained therein are not authenticated. Until such time as Thailand adopts an annual bird report format, the most appropriate journals for publishing new records, and for observers to receive appropriate recognition of their discoveries are either Forktail (the journal of the Oriental Bird Club) or Natural History Bulletin of the Siam Society (NHBSS). The author is on the editorial bird of NHBSS and will undertake to assist any observer who wishes to publish there. It would probably be appropriate for the first three records of any new migrant species, and at least the first record of any new resident species to be published therein.

» Summary

Overall , I can summarise by saying that field ornithology in Thailand is making very rapid progress and we can look forward to what the next decade or so will bring. It promises to be an exciting and dynamic time for all of us.

» References

Alstr?m, P., U. Olsson and P.D. Round., 1991. The taxonomic status of Acrocephalus agricola tangorum. Forktail 6: 3–13.
Alstr?m, P., U. Olsson and P.R. Colston. 1992. A new species of Phylloscopus warbler from central China. Ibis 134:329–334.
Alstr?m, P., U. Olsson and P.R. Colston. 1997. Re-evaluation of the taxonomic status of Phylloscopus proregulus kansuensis Meise. Bull. Brit. Orn. Cl. 117(3): 177–193.
Alstr?m, P. and U. Olsson 1999. The Golden-spectacled Warbler: a complex of sibling species, including a previously undescribed species. Ibis 141(4): 545–568.
Grimmett, R., C. Inskipp and T. Inskipp. 1998. Birds of the Indian Subcontinent. Croom Helm, London
Inskipp, T., N. Lindsay and W. Duckworth. 1996. An Annotated Checklist of the Birds of the Oriental Region. Oriental Bird Club, Sandy, U.K.
Leisler, B., P. Heidrich, K. Schulze-hagen and M. Wink, 1997. Taxonomy and phylogeny of reed warblers (genus Acrocephalus) based on mtDNA sequences and morphology. Journ. fur Ornithologie 138: 469–496.
Lekagul, Boonsong and P.D. Round. 1991. A Guide to the Birds of Thailand. Saha Karn Bhaet, Bangkok.
McGowan, P.J.K. and A.L. Panchen., 1994. Plumage variation and geographical distribution in the Kalij and Silver Pheasants. Bull. Brit.Orn. Cl. 114(2): 113–123.
Robson, C. 2000. An identification guide to the birds of South-East Asia. New Holland, London.
Round, P.D. 1987. New species of birds in Thailand, 1974–1987. Paper presented at National Wildlife Seminar, Kasetsart University, 24 December 1987.
Sibley, C.G. and B.L. Monroe, Jr. 1990. Distribution and taxonomy of birds of the world. Yale University Press, New Haven.
Wells, D.R. 1999. The Birds of the Thai-Malay Peninsula, vol. 1. Non-passerines. Academic Press, London.

Table 1.New bird records for Thailand, 1989–1999