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| The
Avifauna of the Mo Singto Forest Dynamics Plot, Khao Yai National
Park, Thailand By Philip D. Round, Andrew J. Pierce, Wangworn Sankamethawee & George A. Gale |
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| Abstract The 169 species of birds recorded on the 30 ha Mo Singto Forest Dynamics Plot, Khao Yai National Park, Thailand, are a subset of the 329 species recorded in the headquarters area of the park. Most of the Mo Singto-recorded species are typical of evergreen forest interior but the transient occurrence of a small number of other species, inhabitants of forest edge or more open habitats, is documented. Almost one third of species found on the plot were moderate to long-distance migrant, non-breeding, visitors. The largest foraging guilds were foliage-gleaning insectivores and sallying insectivores, together accounting for over one-third of all species. Though obligate frugivores were poorly represented, most insectivorous birds incorporated fruits in their diet. The nearly 30-year history of avian recording at Mo Singto, with intensive community studies having been conducted in the past decade, and the location of the study plot near the submontane-montane transition, make it an ideal site for continuation of detailed monitoring, particularly that related to the impact of climate change. |
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| INTRODUCTION Observations of birds at Mo Singto, in Khao Yai National Park, have been made for as long as observations have been conducted on gibbons (Brockelman & Gittins, 1984; Marshall et al., 1972; Marshall & Sugardjito, 1986), and for almost the same duration as on birds in the wider park area. Systematic compilation of a Khao Yai avifauna began soon after the park’s establishment (Dickinson, 1963, 1967; Dickinson & Tubbbb, 1964, 1966; McClure, 1974). Both gibbon researchers and birdwatchers collected information on birds on the Mo Singto Forest Dynamics Plot (hereafter MFDP) from at least the early 1980s. A comprehensive inventory of the birds of Khao Yai and adjacent areas in what is known as the Dong Phaya Yen Forest Complex, was given in Lynam et al. (2006) with updates in Pobprasert et al. (2008). The establishment of a marked grid in 1998 provided a new opportunity and incentive to conduct detailed studies of the bird community involving individual colour-marking, territory mapping of birds, evaluating census methods, and studies of breeding biology and social behaviour (Dhanasarnpaiboon & Round, 2004; Gale et al., 2009; Nimnuan et al., 2004; Pierce, 2004, 2005, 2009; Pierce & Pobprasert, 2007; Pierce and Round, 2006; Pierce et al., 2004a, 2004b, 2007; Pobprasert & Gale, 2010; Pobprasert & Pierce, 2010; Pobprasert et al., 2008; Praditsup et al., 2007; Round & Gale, 2008; Round et al., 2006; Sankamethavee et al., 2009, 2010; Savini & Sukumal, 2009; Sukumal & Savini, 2009a, 2009b; Sukumal et al., 2010; Steward, 2010; Tokue, 2007.) Detailed inventories and long-term data sets for tropical forest sites are rare. Round (1984) assessed avifaunal changes at another Thai site, Doi Suthep-Pui, over a 50-year period. Turnover, encompassing both apparent losses due to hunting and habitat degradation, and many additions (“new” records), was documented over this period. Assessment of faunal change is complex: some turnover may be stochastic in nature; some species may be extirpated through human activity; other “genuinely new” species may colonize due to changes in the environment or appear for short periods in response to ephemeral disturbance. Increased observer effort through time at any site will inevitably accumulate new records. Increasingly, climate change is recognized as a major anthropogenic disturbance that not only impacts habitats and plant distribution, but also causes distributional and behavioural changes in animals (e.g. Crick & Sparks, 1999; Hickling et al., 2006; Schaefer et al., 2006). Because of MFDP’s location in the heart of the 2,169 km2 Khao Yai National Park its avifauna is exempt from hunting and most forms of direct human disturbance (though even there, some collection of high-value forest products, such as Aquilaria wood, is still carried out; Brockelman et al., 2011). The location of MFDP may prove to be an especially fortuitous choice for studying climate change-related impacts on the bird community since the plot is situated close to the lowland-montane ecotone (for Thailand and tropical SE Asia usually placed at 900–1000 m elevation; Neal 1967; Whitmore, 1975). Round & Gale (2008) demonstrated major changes in the relative abundance of two pheasant species (one lowland, one montane) in and around MFDP over a two-decade period which they hypothesized was related to warming temperatures. The purpose of this paper, therefore, is to provide an updated inventory of bird species recorded on the Mo Singto Forest Dynamics Plot and to discuss this in the larger context of the park of which it is a small part. This will provide a baseline for assessing future turnover in the bird community, and will also be useful as a reference for ecological studies of interactions such as seed dispersal and predation. |
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| STUDY
AREA & METHODS Details of MFDP are set out in Brockelman et al. (2011). In brief, it is an area of 30 ha, located in closed-canopy, moist, evergreen forest habitat at elevations of 725 to 815 m. It lies within 500 m of the forest edge and park headquarters. The range of habitats and species diversity of plants and animals in the immediate surroundings was likely increased by the large expanse of forest clearings, formerly settled and cultivated areas, which became Imperata grassland and scrub when the park was established in 1962. Though grasslands are still burnt during management, clearings are gradually reverting to scrub and secondary forest. No clearings exist within the plot itself. The species listed (Table 1) are all those recorded within the confines of the present-day plot. This includes those recorded opportunistically by birdwatchers and biologists from 1980 onwards; and those noted during systematic censuses of MFDP during 2002–2006 and subsequently (Pierce & Round, 2006; Round et al., 2006; Pobprasert et al., 2008; Gale et al., 2009). It also includes species seen in the airspace over the plot. Observations were carried out year-round and the records also include species detected by mist-netting and capture in baited spring-traps. Nocturnal birds were detected both on and in the immediate vicinity of the plot by listening for calls at night while walking forest trails (though much less search effort was concentrated at night than during the day). All sight photographic and aural records (both those of the authors and those submitted by outside observers) were authenticated by peer-review. The plot constitutes a small part of a plateau in the north-west quadrant of the park. This relatively homogeneous habitat and elevational zone, extending to the rim of the northern park scarp, and southwards to the summit of the Khao Khieo–Khao Rom scarp (1,350 m), and eastwards to the Haew Suwat waterfall, covers an area of roughly 60 km2. This corresponds to the “headquarters area” (hereafter Hq area) of the park. It is traversed by roads and trails and therefore frequently visited. At higher elevations, the forest grades into a montane forest type. At lower elevations, around the northern rim, it grades into a drier, semi-evergreen or mixed deciduous facies. Besides providing a comprehensive listing of bird species known for MFDP, we have also listed all other species known for Hq area with reference to the baseline inventory for the park in Lynam et al. (2006) and Pobprasert et al., 2008 (Table 2). We have omitted species listed by other authors where it cannot be established whether the records were from the Hq area as defined above. We discuss those that might have the potential to either colonise, disperse or stray into MFDP due to habitat change induced by ecological succession, human-induced or natural disturbance, or during random turnover. Taxonomic order and nomenclature are based on Robson (2008). |
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| RESULTS Species Found on MFDP The 169 species recorded on MFDP (both residents and migrants or winter visitors) are a subset of the total of 329 species which have been recorded in the Hq area of the park as a whole (Table 1, Table 2). Of the MFDP-recorded species, 112 are thought to be resident (either on MFDP itself or in the immediately adjacent Hq area); one is a wet-season breeding visitor; 47 species are considered non-breeding (winter) visitors, seven are spring and autumn passage migrants. At least two species recorded on MFDP are represented in the park by both resident and wintering populations (Table 1). Of these, 128 are more or less regular on MFDP, while another 41 are considered rare (< 10 sightings). In general, MFDP was very intensively surveyed and most rare species were considered to be genuinely rare, either because they were birds that tended to occur at low density and had large territories (e.g. most raptors) or were those normally characteristic of more open habitats. At least one aerial feeder (e.g. Asian House-martin) may have been under-recorded due to the difficulty of observing them from within closed canopy forest. |
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| Table
1. List of bird species recorded on the Mo Singto Forest
Dynamics Plot, Khao Yai National Park. Seasonal status: resident/presumed resident (R); non-breeding visitor (N); breeding visitor (B); passage migrant (P); [ ] rarely recorded on plot (< ten records). Habitats: grassland or scrub (G); forest or woodland (F); aerial feeders (A) Guilds: Following Johns (1986), terrestrial insectivore–frugivore (TIF), bark-gleaning insectivore (BGI), arboreal insectivore–frugivore (AIF), arboreal faunivore/frugivore (FF), foliage-gleaning insectivore (FGI), terrestrial insectivore–faunivore (TIV), piscivore (P), diurnal or nocturnal raptor (R), sallying insectivore (SaI), sweeping insectivore (SwI), terrestrial insectivore (TI), insectivore–nectarivore (IN). |
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| * Two taxa, Claudia’s Warbler Phylloscopus claudiae and Hartert’s Warbler P. goodsoni constitute a monophyletic group with Blyth’s Leaf-warbler P. reguloides, with which they were formerly treated as conspecific (Olsson et al., 2005). The Khao Yai-wintering taxon is tentatively listed as P. claudiae but the possibility that it might instead be P. goodsoni, recently recorded in N Laos by Fuchs et al. (2007) has not been excluded with certainty. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Table 2. List of additional bird species recorded in headquarters area of Khao Yai National Park. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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| HABITAT
USE Most species that occur on MFDP are inhabitants of the edge or interior of evergreen forest. Some are shared with either deciduous forest or secondary growth. Many have a broad altitudinal range, but there are no exclusively montane species. Some rarer MFDP species are larger birds that naturally occur at low density (Table 1). Great Slaty Woodpecker Mulleripicus pulverulentus, for example, is scarce in the Hq area of the park and is mostly found in association with lowland, old-growth forests (Lammertink et al., 2009). Mountain Hawk-eagle Nisaetus nipalensis and Malaysian Night-heron Gorsachius melanolophus may be similarly scarce. The former is assumed to require large territories, while the latter is secretive in addition to its apparent scarcity and seems primarily to inhabit lowlands (Lekagul & Round, 1991; Thewlis et al., 1998). Scaly-crowned Babbler Malacopteron cinereum may be representative of lowland species that approach their upper altitudinal limit on the plot. It appears to be patchy and thinly distributed in the Hq area of Khao Yai. Some others have a special association with a particular habitat (e.g. Pin-tailed Parrotfinch Erythrura prasina is a semi-nomadic specialist in seeding bamboo (Lekagul & Round, 1991; Wells, 2007). The scarcity of some others is harder to explain. Velvet-fronted Nuthatch Sitta frontalis occurs across a wide range of elevations, from lowlands to the montane zone. Its extreme scarcity on the plot (and, incidentally elsewhere in the Hq area) may be due to a preference for slightly more open forest than is found around the interior of Khao Yai. The species evidently bred on or near the plot in 2005, when there were four sightings during March–August, one of which involved two adults and two fledglings. None was recorded in subsequent years, however. At least two rare, resident, plot-recorded species, Blue-eared Kingfisher Alcedo meninting and Slaty-backed Forktail Enicurus schistaceus, are riparian species associated mostly with larger streams that move into MFDP (presumably from the Lamtakhong River) in mid- to late wet season as the few small streamlets that traverse the plot become swollen. Five resident species recorded infrequently on MFDP but typical of more open habitats include Greater Coucal Centropus sinensis, Spotted Dove Streptopelia chinensis, Racket-tailed Treepie Crypsirina temia, Common Tailorbird Orthotomus sutorius and White-rumped Munia Lonchura striata; Table 1). These are either characteristic of, or regularly enter, open, deciduous woodland and bamboo (Lekagul & Round, 1991) and all but Racket-tailed Treepie are regularly present in edge habitats around the headquarters. There were several records of Racket-tailed Treepie, a bird of lowland deciduous habitats and scrub, often close to standing water (Lekagul & Round, 1991; Robson, 2002) in both the headquarters area of the park and on MFDP during 2004–2005 but the species evidently did not establish itself and has since seemingly since vanished from the park headquarters area. A sixth species, Plain Flowerpecker Dicaeum minullum, may also be placed with this group, in that it is regularly present in disturbed, more open woodland habitat around park headquarters. It probably tends to be associated with taller, better quality forest than the other members of this group, occurring elsewhere across a wide altitudinal range to an elevation of 1700 m (Lekagul & Round, 1991). Most other species that occur infrequently on MFDP are migrants or non-breeding visitors found in a range of habitats. Chinese Pond-heron Ardeola bacchus is a waterbird that occasionally enters closed forest along streams. |
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SEASONAL STATUS The absence of resident populations of some of these species may be due to a variety of factors. The relative homogeneity of the closed evergreen forest habitat; the elevation of the plot, above the upper elevational limits of some species (itself presumably a consequence of preference for more open, deciduous or forest mosaic habitats) and historical (biogeographical) factors may all contribute. The Khao Yai Hq area is at too great an elevation to support the full complement of lowland (deciduous or forest mosaic) species, yet lacks any compensating diversity of either montane or other evergreen forest species (Lynam et al., 2006). The same authors argued that the relatively depauperate nature of the resident evergreen forest avifauna might stem from Khao Yai constituting a relatively isolated block of evergreen forest which during Pleistocene interpluvial periods, would have been smaller than at present, surrounded by deciduous habitats, with even fewer connections to other evergreen isolates elsewhere in Thailand: to the north, south and east. In a study of mixed species foraging flocks on MFDP, Nimnuan et al. (2004) found 58 species (residents and migrants) that regularly participated. Although residents contributed 74% of individuals found in flocks, the sightings were biased towards resident species as the survey covered only the months May–October, when most migrants were absent. Even so, the most numerous birds counted (136 of 956 individuals, 14 % of all sightings) were one or two species of (migrant) leaf-warbler. If migrant species are excluded from the analysis, the relatively depauperate nature of the MFDP avifauna is immediately apparent. Just 11 species of resident bird contributed 67% of sightings of birds in flocks. The two predominant arboreal species, White-bellied Erpornis Erpornis zantholeuca (69 sightings) and Black-naped Monarch Hypothymis azurea (53 sightings) together contributed 17% of all individuals observed. The single most abundant understorey-middle storey species on MFDP is the Puff-throated Bulbul Alophoixus pallidus (3.4 individuals/ha, Gale et al., 2009) which is chiefly associated in territorial groups and contributed few (1.5%) mixed flock sightings. |
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FORAGING
GUILDS Assigning species to guilds is necessarily imprecise. The seeds of small fruits were detected in the faeces of many ostensibly insectivorous species that were handled, including Abbott’s Babbler Malacocincla abbotti, scimitar-babblers Pomatorhinus spp. and all three laughingthrushes (Dryonastes chinensis and Garrulax spp.). Both Laced Woodpecker and Greater Flameback were seen eating fruit. Among the commoner resident insectivores, only Hill Blue Flycatcher Cyornis banyumas has not yet been observed to take fruit. Other true flycatchers (Verditer Flycatcher Eumayias thalassinus, Taiga Flycatcher Ficedula albicilla) and “flycatcher guild” sallying insectivores such as Black-naped Monarch are likely to take fruits on occasion. While most neotropical trogons take a considerable proportion of fruit in their diet (Pizo, 2007; Remsen et al., 1993; Riehl & Adelson, 2008), the Asian species are primarily foliage-gleaning insectivores (Ali & Ripley,?,? 1983? ;Johnsgard,?,? 2000; Steward,? 2010; Wells, 1999). Nonetheless both Red-headed Trogon Harpactes erythrocephalus and Orange-breasted Trogon H. oreskios at Khao Yai have now been observed to take a small proportion of fruits. In comparison with Sundaic lowland forest bird communities such as those at (e.g.) Pasoh and at Kuala Lompat, Malaysia (Francis & Wells, 2003; Wong, 1986), Khao Yai appears to have more generalist omnivores and fewer specialist insectivores or frugivores. |
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| DISCUSSION A further 160 species (loosely divided into 60 forest or woodland inhabiting species, 70 grassland or scrub-associated species and 30 waterbirds and riparian species) have been recorded in the Hq area without being either seen or heard on MFDP (Table 2: Lynam et al., 2006; Pobprasert et al., 2008). The occurrence of so many species elsewhere in the Hq area relative to the number on MFDP can be attributed to the much larger area, and greater range of habitats, around the park Hq as a whole compared with the closed forest habitat of the plot. These additional habitats encompass grassland (both tall grass and mown grass or lawn), scrub, forest edge, roadside verge, parkland, large streams with associated riparian habitats, reservoirs, human habitations, power lines and other installations which provide nesting of foraging niches for a few species. The 60 forest-inhabiting species comprise 23 resident/presumed residents and 37 migrants/non-breeding visitors, all of which may have the potential to occur on MFDP. At least two of the resident species, Lesser Yellownape Picus chlorolophus and Grey-capped Pygmy Woodpecker Dendrocopos canicapillus (the latter reported as “absent from the Hq area” by Lynam et al., 2006, but presence since noted in at least one season: author), seem to share the habitat preference of Velvet-fronted Nuthatch in that they occur across a wide range of elevations, often in more open forest. However they also occur in tall, mature, closed-canopy, lowland forest. The scarce lowland resident Moustached Hawk-cuckoo Cuculus vagans, two passage migrants (Ruddy Kingfisher Halcyon coromanda and Chinese Sparrowhawk Accipiter soloensis) and the scarce winter visitor Rufous-tailed Robin Luscinia sibilans have all been seen on the Mo Singto Nature Trail or elsewhere in the vicinity of the plot margins, and are therefore almost certain to occur on MFDP occasionally. A small number of birds (e.g. White-tailed Leaf-warbler Phylloscopus ogilviegranti, White-browed Shrike-babbler Pteruthius flaviscapis and Chestnut-fronted Shrike-babbler P. aenobarbus) are montane residents, and could conceivably disperse downslope to the elevation of the plot although the park populations of these species are relatively small, due to the limited areas of montane habitat and therefore the chances of detecting them may be slight. The occurrence of some others, mainly lowland deciduous woodland, species (e.g. Red-breasted Parakeet Psittacula alexandri, Lineated Barbet Megalaima lineata and Golden-fronted Leafbird Chloropsis aurifrons) that occur chiefly around the margins of the headquarters plateau, at the deciduous-evergreen ecotone, is unlikely at present but could be plausible, especially if warming temperatures cause significant drying of the moist forest habitat. The apparent absence from MDFP of some forest birds may simply be due to the difficulty of observing them in the canopy of enclosed forest—most records of (e.g.) migrant flycatchers are from forest edge, from the roads or other open areas. The 70 species of grassland-scrub inhabiting birds recorded elsewhere in the Khao Yai Hq area may be divided into 39 non-breeding winter visitors and 31 residents. Their absence from MFDP is noteworthy given the relative proximity of such open habitats. Many of these open-country species (e.g. Red-wattled Lapwing Vanellus indicus) have colonized the headquarters area of the park within the past 20 years or so. Common Myna Acridotheres tristis, first recorded c. 2000, and White-vented Myna A. grandis, found as recently as 2006 (PDR own data) are even more recent arrivals. Natural habitat perturbation (e.g. major tree-falls caused by whirlwinds, affecting areas up to 0.3 ha) has occurred just off-plot at Mo Singto, and such infrequent natural events could in future create transient conditions on MFDP that might permit the temporary occurrence of smaller open country birds. Additionally most migrant species, including inhabitants of open country, have the potential to stray, and occur in unusual situations, and could therefore occur on the plot from time to time. Most waterbirds, on the other hand, have no likely prospects of being found on the plot due to the lack of significant water bodies (with the possible exception of riparian species such as kingfishers that may move up flood-swollen smaller tributaries in the wet season). |
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| DISCUSSION While the avifauna of the Mo Singto Plot is largely composed of birds typical of the interior of evergreen forest, that around the larger headquarters area of Khao Yai National Park contains a wider array. In addition to evergreen forest species (including a very few montane species) are a few species more typical of deciduous forest habitats and bamboo; those that inhabit grassland and scrub, and waterbirds. Even so, some of these species occur at low densities or are distributed patchily around the headquarters area, or are rare or occasional transient visitors. What Future Changes Might We Expect? Some turnover of species is a natural process which might be expected even without any human disturbance. Since Khao Yai was established as a park in 1962 the most obvious trends (inferred or observed) have been decreased direct persecution of birds and increased use by tourists. There has been a gradual increase in infrastructure (roads, buildings and other facilities) but impact on forest appears to have been slight. So far as known, no species has been lost since avifaunal recording started. Habitat succession Grasslands around the park Hq are derived from former cultivated fields and have been variously maintained by either burning or mowing as a means to maintain open grassy areas for ungulates (especially Sambar Rusa unicolor). While the respective merits of the two grassland management regimes (burning and mowing) have not been fully assessed it is nonetheless undeniable that many areas of former grassland around the park headquarters are gradually reverting to scrub and secondary forest, and this will undoubtedly cause some grassland-inhabiting species recorded in the park Hq area to decline or even disappear. Blue-breasted Quail Coturnix chinensis (already rare in the park), buttonquails Turnix spp., Red-whiskered Bulbul Pycnonotus jocosus, Bright-capped Cisticola Cisticola exilis, prinias Prinia spp., and grassland-inhabiting migrants such as Blunt-winged Warbler Acrocephalus concinens are representatives of this group. None of these species has been recorded on MFDP. The loss of grassland will impact on the overall species richness of the park Hq area without adding any further forest-living species. Human persecution Species that were formerly hunted (e.g. pheasants Lophura spp. and Red Junglefowl Gallus gallus; pigeons, especially Mountain Imperial-pigeon Ducula badia) would probably have increased in the first decade or more after the park’s establishment and are now more or less common. Assuming that populations of these have probably reached carrying capacity, further population increase would seem unlikely (though some may have become more easily detectable due to behavioural habituation). Illegal forest product collecting continues (Brockelman et al., 2011) and has the potential to pose a possible threat should any bird species be targeted by poachers. The communally roosting Red-whiskered Bulbul is known to be widely targeted elsewhere by commercial bird trappers supplying the cagebird trade, and numbers in the park Hq area, seemingly already diminishing, possibly due to habitat change, could be potentially at risk from poachers. Hornbill chicks, widely targeted elsewhere (and certainly at risk in peripheral regions of Khao Yai), are not known to have been poached in the immediate Hq area. Evidence has emerged of a trade in owl carcasses from Malaysia, (apparently destined for the restaurants in China; Shepherd & Shepherd, 2009) while owls are much persecuted in Laos, and frequently seen in captivity (Duckworth et al., 1999). They could therefore also be at elevated risk in peripheral areas of Khao Yai and other Thai protected areas. Increased recreational use The main direct human uses are tourism-related. In general there has been a great increase in vehicular traffic, and also foot traffic on park trails that approach within 100–200 m of the plot. There may be occasional cases where nests are abandoned due to inadvertent disturbance, or birds killed by vehicular collision, but because both roads and trails affect relatively limited areas, the impact is likely to be small. Road construction may well have contributed to the colonisation of the park Hq by open country species, however, since roads provide a narrow ribbon of edge habitat connecting the park margins with the park interior. Canalization and concreting of small sections of riverbank, and the expansion of tourist facilities along waterways, could impact some riparian species, including bank-nesters such as kingfishers and forktails in the heavily used and developed Hq area. A possible indirect effect of increased recreational use on the avifauna could be increased usage of forest around park Hq by the generalist omnivore Northern Pig-tailed Macaque Macaca leonina. Formerly either shy or scarce, macaques have learnt to utilize garbage and (illegal) hand-outs from tourists, and, now habituated, routinely beg for food along roadsides. They have become much more detectable in the past two decades, suggesting the possibility that their total population has increased. Macaques are the most frequently recorded predator of bird nests on MFDP (Pierce & Pobprasert, in prep.). If presently observed levels of nest predation by macaques are higher than formerly this might have the potential to induce changes in the productivity of the resident avifauna. Climate change Round & Gale (2008) postulated that changes in the relative abundance of two pheasant species in the park headquarters area were due to rising temperatures that favour species characteristic of lowland, semi-evergreen forest at the expense of those that favour moister, montane or submontane conditions. Formerly only Silver Pheasant Lophura nycthemera was found on MFDP but in the past 15–20 years sightings of this species have been overtaken by lowland-inhabiting Siamese Fireback L. diardi. Other species that favour moist, sub-montane and montane, evergreen forest that are at present relatively frequent on MFDP, but that could decline, include Red-headed Trogon, the broadbills Serilophus lunatus and Psarisomus dalhousiae, and possibly Common Green Magpie Cissa chinensis, Hill Blue Flycatcher, and Fire-breasted Flowerpecker Dicaeum ignipectus. Corresponding lower elevation species that might increase in abundance include Orange-breasted Trogon, Banded Broadbill Eurylaimus javanicus, Racket-tailed Treepie, Hainan Blue Flycatcher Cyornis hainanus and Plain Flowerpecker. As already indicated, other species at present more typical of deciduous woodland and edge habitats might colonise the plot if rising temperatures induce significant change in the vegetation towards a semi-evergreen or deciduous facies. Migrant species are at elevated risk from climate change (Coppppack & Both, 2002; Butler, 2003). Migrants have evolved migration strategies in response to a narrow range of environmental conditions on their breeding and wintering areas, each of which is affected by climate-change to a differing extent. While some tropical or sub-tropical wintering species may have adjusted their arrival times on their Palearctic breeding grounds in synchrony with earlier warm temperatures, other species have failed to do so. In some, this has led to loss of synchrony between an earlier-peaking food supply and production of young (which has not advanced as correspondingly early) reducing breeding success and survival of young (Both et al., 2006). Changing weather patterns have likewise impacted the wintering areas of migrant birds. The winter survival of many western Palearctic breeding, Afrotropical wintering, migrants has been adversely affected by reduced rainfall and increased desertification in north equatorial Africa (Peach et al., 1991; Baillie & Peach, 1992; Sanderson et al., 2006). There is much less information on the Eastern Palaearctic-Indo-Malayan migration system. However, the preponderance of migrant birds in Khao Yai, both Palaearctic and Sino-Himalayan species, offers significant opportunity for detailed studies of their ecology and survival. |
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| FUTURE
RESEARCH This paper is largely descriptive. Continued monitoring of avifaunal change on the Mo Singto Plot and elsewhere in the park headquarters is a priority for the future. Besides maintaining the inventory and documenting turnover of species, this should include monitoring of annual population levels of both resident and migrant bird species, through continued use of territory mapping combined with distance sampling or other detectability-based estimates. Preliminary data on density and biomass (Round et al., 2006) is available for a wider range of species than treated in Gale et al. (2009) but needs revising and updating in the light of the latter’s caveats on interpretation. Monitoring of bird population levels combined with detailed studies that yield information on (e.g.) productivity and habitat use by birds, together with detailed monitoring of forest dynamics may help understand the implications of climate-related environmental change for biodiversity conservation. |
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| ACKNOWLEDGEMENTS We thank Warren Brockelman, Will Duckworth and James Steward for commenting on drafts of this paper. We are grateful to the Department of National Parks, Wildlife and Plants Conservation for facilitating our work in Khao Yai. We thank the Biodiversity Research and Training Programme (BRT) for supporting fieldwork during 2003–2006. Philip Round is also supported by The Wetland Trust. |
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REFERENCES |
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| Kindly
submitted by: Philip D. Round, Department of Biology, Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400, Thailand. E-mail: frpdr@mahidol.ac.th Andrew J. Pierce, Conservation Ecology Program, School of Bioresources & Technology, King Mongkut’s University of Technology Thonburi, 83 Moo. 8 Thakham, Bangkhuntien, Bangkok 10150, Thailand. E-mail: george.and@kmutt.ac.t George A. Gale, Conservation Ecology Program, School of Bioresources & Technology, King Mongkut’s University of Technology Thonburi, 83 Moo. 8 Thakham, Bangkhuntien, Bangkok 10150, Thailand. E-mail: george.and@kmutt.ac.t Wangworn Sankamethawee, present address: Walai Rukhavej Botanical Research Institute, Mahasarakham University, Mahasarakham 44150, Thailand |
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