Porcupine! 18 - Special feature: Focus on farmlands

Much of the remaining vegetated lowland in Hong Kong falls into the category of 'agricultural land', even in places where farming has long been discontinued. Such land, which ranges from cultivated vegetable fields and orchards to open grass/shrub/marshland, lies mainly outside of the Country Parks and is therefore prone to development pressure (total area of agricultural land, excluding ponds, fell from 6,700ha in 1992 to 6,080ha in 1997, according to government figures). However, Hong Kong's farmlands do support a wide range of local fauna. The problem of habitat fragmentation for woodland fauna would be exacerbated if overgrown, disused farmland were to be replaced by managed landscapes. Generally speaking, the longer the land has been disused, the more valuable it is in providing food and cover for such animals. Wu Kau Tang and the Sha Lo Tung basin, in the NENT, are good examples of areas with high biodiversity value in which long-disused agricultural land is a major component of the landscape.

The following report, which focuses mainly on birds, is an attempt to summarise the relative importance of agricultural land in the context of Hong Kong's terrestrial fauna.

BIRDS
What is agricultural land?

Whilst the bird communities in Hong Kong of such habitats as wetlands, forest and shrublands are relatively amenable to definition, it is less straight-forward to define the bird community of agricultural land. In Hong Kong, historically, agricultural land has formed as a patchwork within a largely anthropogenic landscape, all possible products of which were directly utilised by man. Thus, a definition of the bird community of farmland must be integrated into a framework which establishes which of the components of this landscape are defined as agricultural land. Government land use categorisations or traditional usage of land result in, respectively, too narrow or too broad a definition of just what constitutes agriculture, and the unique history of land ownership and land use in Hong Kong renders comparisons with international usage of terms largely meaningless.

Accordingly, whilst recognising that the following definition is reductionist, the bird community of agricultural land has been defined as the populations of birds which utilise areas where a human community is engaged in production of terrestrial crops or animals. Thus, it includes areas which are temporarily or permanently not used for this purpose but which are an integral part of areas where production is taking place, such as fallow fields, or ponds and channels associated with irrigation works. Excluded are areas where agriculture has been permanently abandoned, fung shui woods and areas where production is based on an aquatic system such as fishponds and gei-wai.

Within this framework, there are major differences between the bird communities found in areas where water is permanently utilised for irrigation (here termed wetland agriculture) and areas where there is no surface water for at least a part of the year (dryland agriculture).

At least from an ornithological perspective, dryland agriculture is characterised by a patchwork of vegetable and flower crops, orchards and tree nurseries. Interspersed with active agricultural areas are houses and fallow fields, the latter either covered with broad-leaved herbs or perennial grasses or woody shrubs, depending upon the period of abandonment.

The bird community of these areas is characterised by generalists, most of which are also found in areas of wetland agriculture, the urban fringe and on landfill or open storage sites. Thus, the most conspicuous resident species are Spotted Doves Streptopelia chinensis, Hong Kong's three species of Pycnonotus bulbul, Oriental Magpie Robin Copsychus saularis, Yellow-bellied Prinia Prinia flaviventris, Common Tailorbird Orthotomus sutorius, Masked Laughingthrush Garrulax perspicillatus, Long-tailed Shrike Lanius schach, Black Drongo Dicrurus macrocercus, Black-collared Starling Sturnus nigricollis and Crested Mynah Acridotheres cristatellus. Of these species, dryland agriculture is perhaps most important for Long-tailed Shrike and Black-collared Starling, though both these species are equally, if not more, common in wetland agricultural areas.

One species of summer visitor, the Plaintive Cuckoo Cacomantis merulinus is, however, primarily restricted to this habitat. This cuckoo is a brood-parasite on the Common Tailorbird (Carey et al. in prep.), but unlike that species does not occur in shrubland or forest. Amongst the non-breeding visitors, a number of passerines favour this habitat and for several of these it is important. Of the Turdidae, the Daurian Redstart Phoenicurus auroreus and the Common Stonechat Saxicola torquata are conspicuous. Both these species also utilise upland areas of grassland with shrubs, and the Common Stonechat is found in lowland grassland areas, but their numbers are at least as great in dry farmland as elsewhere. Dry farmland also provides habitat for a number of granivores of which the greatest numbers, both of species and birds, are buntings, Emberiza spp. The Black-faced Bunting E. spodocephala is probably the most abundant and is certainly the most widespread of these, but dry agricultural areas are relatively more important for Chestnut-eared Buntings E. fucata, Little Buntings E. pusilla and Yellow-breasted Buntings E. aureola. Whilst the latter two species occur, especially as passage migrants, in other open habitats (including wetland agricultural areas), the Chestnut-eared Bunting is now largely restricted to dryland agricultural areas and is much rarer in Hong Kong than it was during the 1930s to 1950s. This may have been a species which made use of rice fields in Hong Kong as it did in Guangdong (Vaughan and Jones 1913), but the reason for the decline in Hong Kong is unknown, Yellow-breasted Buntings have also declined significantly in Hong Kong in the last 30 years and it is strongly suspected that this is a consequence of increased trapping for food in China (Carey et al. in prep.).

Three other granivorous passerines, all of which have declined in Hong Kong in the last 30 years, are also particularly associated with dryland agriculture. The Common Rosefinch Carpodacus erythrinus, has never been common in Hong Kong, but is now rare, whilst the Crested Bunting Melophus lathami was formerly a common breeding species in the uplands and wintered in lower elevation agricultural areas nearby. The reasons for the decline in numbers of both these species are unclear and may differ, since the Crested Bunting appears always to have been resident in Hong Kong, whilst the rosefinch is a winter visitor. Finally the Yellow-billed Grosbeak Euphona migratoria is a winter visitor associated with areas of orchards, which has declined greatly since around 1980. It seems likely that this decline is a consequence of an increase in exports from China to Europe and North America for the cage bird trade (Clements et al. 1993, Carey et al. in prep.). Dryland agriculture is, in general, less important for non-passerine species; but it is the main habitat utilised by Black-winged Kite Elanus caeruleus which is a recent, and still very rare colonist. It is also an important habitat for the Japanese Quail Coturnix japonica, which is a scarce winter visitor. The unrelated, but superficially similar Yellow-legged Buttonquail Turnix tanki and Barred Buttonquail T. suscitator probably also utilise it to a significant extent but their status in Hong Kong remains obscure.

Wetland agriculture in Hong Kong, though formerly dominated by rice production, is now largely associated with the production of vegetable crops, notably Water Spinach Ipomoea aquatica and Watercress Rorippa nasturtium-aquaticum. Both these crops are cultivated in flooded or at least damp fields and the resulting management regime produces a series of wetland microhabitats ranging from flooded ditches and reservoirs and fields covered with shallow water to marshy fields with emergent herbaceous vegetation. Furthermore, the patchwork of land ownership and management regimes results in areas of wet grassland and temporarily abandoned herb-filled fields and, at least at Long Valley, damp fields are retained for the pasturing of domestic Water Buffalos, providing yet another microhabitat.

With a few exceptions, discussed above, wetland agricultural areas generally support those species which are found in dryland agricultural areas, together with others which elsewhere occur in brackish or salt water wetlands. However, it is the use of this habitat by species which are freshwater specialists which requires special attention. Most ardeids in Hong Kong utilise areas of wetland agriculture to some extent, but it is particularly important for the breeding populations of Cattle Egrets Bubulcus ibis, perhaps especially where Water Buffalo are present, and migrant populations of the Cinnamon Bittem Ixobrychus cinnamomeus and the globally threatened Schrenck's Bittern I. eurhythmus. The Cinnamon Bittern formerly bred in Hong Kong, being a summer visitor to rice paddies in the Deep Bay area (Dove and Goodheart 1955), but now appears to be solely a passage migrant, though it still breeds in rice paddies in Guangdong (pers. obs.).

The most celebrated bird species of wetland agriculture in Hong Kong is, however, the Greater Painted-snipe Rostratula benghalensis which has now been demonstrated to depend entirely on such areas for its continued survival as a breeding species in Hong Kong (Leader in prep.). Only two populations are now known: at Long Valley and at Kam Tin, though as a consequence of recent developments, the Kam Tin population is now associated with abandoned rather than cultivated agricultural land.

Closely associated with the Greater Painted-snipe in terms of habitat preferences, though showing wider tolerances, are the three species of "true" snipe occurring in Hong Kong: the Common Snipe Gallinago gallinago, the Pintail Snipe G. stenura and the Swinhoe's Snipe G. megala. The last two of these show a particular preference for agricultural areas over other wetland habitat types. Two other species which formerly bred in Hong Kong, but which are now only present as scarce passage migrants, the Watercock Gallicrex cinerea and the Pheasant-tailed Jacana Hydrophasianus chirurgus are also now most often found in wetland agricultural areas, Unfortunately, however, neither of these species finds them suitable for breeding.

Whilst it is the larger wading birds which have attracted most attention as being dependent upon wetland agriculture, this is also the principal habitat for a series of open country passerines. The Richard's Pipit Anthus richardi, Red-throated Pipit A. cervinus and the Yellow Wagtail Motacilla flava are found especially in fields of Watercress, whilst the Bluethroat Luscinia calliope and the Zitting Cisticola Cisticola juncidis occur in the damp grassland. Other warbler species, notably Luscinia and Acrocephalus spp., also utilise this habitat extensively, though these generally also occur around fishponds and in reedbeds.

A number of species of starling Sturnus reach high densities in areas of wetland agriculture, most notably the White-shouldered Starling S. sinensis and the White-cheeked Starling S. cineraceus. The first of these species was formerly a common breeding bird in Hong Kong, occurring even in urban areas, but is now scarce and some populations, at least, are dependent upon agricultural areas for their survival.

It is becoming increasingly apparent that comparatively little is known concerning the way in which species move between habitats in Hong Kong, and one oversight has been the way in which agricultural land is used by birds during a part of their life cycle. The requirement to conserve not only egretries but also egrets' feeding areas is now widely recognised (Carey et al. in prep,) but for some other species understanding of the use of agricultural land is in its infancy. To take just one example, few ducks Anatidae are found at Long Valley during daytime but several hundred dabbling ducks Anas spp. were recently observed flying there to feed at dusk (Leader, pers. comm.). Such nocturnal use of farmland by Anas spp. is widely known from elsewhere m the world (Cramp and Simmons 1977) but, if this is a regular pattern, may require a re-evaluation of the conservation management strategy for these species.

To put the foregoing discussion in perspective: from the days of Vaughan and Jones (1913) through the time of Herklots (1953) and to the present, birdwatchers in Hong Kong have recognised that agricultural land in Hong Kong has a characteristic bird community and that some species are more readily found in such areas than elsewhere. However, other than the anecdotal approach adopted by Herklots (1951), this habitat has largely been neglected in the published literature. Thus, it is only in the late 1990s, with the realisation that the last few areas of wetland agriculture are under threat, that any attempts have been made to quantify the importance of the bird community of agricultural land. However, whilst some agricultural areas, notably Long Valley, have been the subject of (unpublished) studies, the author is unaware of any previous attempt to bring together published and unpublished observations in order to provide an overview of the importance of agricultural land in a Hong Kong context

Faced with such a blank canvas, the author does not pretend that this synthesis represents the final word on the definition of the bird community of farmland in Hong Kong. However, whilst the details remain to be resolved, the available evidence strongly suggests that agricultural land provides an important habitat for a number of species of birds in Hong Kong and that, in contrast to current thinking in some quarters, the protection of agricultural land is an important conservation priority.

Carey, G.S., Chalmers, M.L., Diskin, D.A., Kennerley, P.R., Leader, P.J., Leven, M.R., Lewthwaite, R.W., Turnbull, M. and Young, L. (in prep.). The Birds of Hong Kong Hong Kong Bird Watching Society, Hong Kong.

Clement, P., Harris, A. and Davis, J. 1993. Finches and Sparrows.Christopher Helm, London.

Collar, N.J., Crosby, M.J. and Stattersfield, A.J. 1994. Birds to Watch 2, the World List of Threatened Birds, Birdlife International, Cambridge.

Cramp, S. and Simmons, K.E.L. 1977. The Birds of the Western Palaearctic: Vol I, Oxford University Press, Oxford.

Dove, R.S. and Goodheart , H.J. 1955. Field Observations from the Colony of Hong Kong. Ibis 97: 311-340.

Herklots, G.A.C. 1951 The Hong Kong Countryside. South China Morning Post, Hong Kong

Leader, P. J. (in prep.). The Greater Painted-snipe in Hong Kong. Hong Kong Bird Report 1997.

Vaughan R.E. and Jones, K.H. 1913. The Birds of Hong Kong, Macao and the West River or Si Kiang in South-East China, with special reference to their identification and Seasonal Movements. Ibis (10) 1: 17-76, 163-201, 351-384.

Birds are very mobile organisms, both as individuals and species. A full list of birds recorded in farmland in Hong Kong would not, therefore, be helpful in defining the ornithological importance of farmland. The following list, therefore, excludes species for which farmland is a minor component of the habitats occupied, aerial species (such as swifts and raptors) unless they are considered to selectively forage over farmland, and species which are of accidental occurrence in Hong Kong (defined as fewer than c.20 records).

Species for which farmland is considered to be the major habitat type utilised in Hong Kong are shown in bold. Seasonal patterns of occurrence are as follows: R (resident), SV (summer visitor), WV (winter visitor) and PM (passage migrant). These codes refer to occurrence in farmland, rather than in Hong Kong. Species names and systematic order follow Carey et al. (in prep). Species indicated with an asterisk are included in Collar et al. (1994).

	Dryland agriculture	Wetland agriculture
**Schrenck's Bittern Ixobrychus eurhythmus***		PM
Cinnamon Bittern Ixobrychus cinnamomeus		PM
Cattle Egret Bubulcus ibis		R
Chinese Pond Heron Ardeola bacchus		R
Black-winged Kite Elanus caeruleus	R	R
Common Kestrel Falco tinnunculus	WV	WV
Eurasian Hobby Falco subbuteo	SV/PM	SV/PM
Japanese Quail Coturnix japonica	WV
Yellow-legged Buttonquail Turnix tanki	PM	PM
Barred Buttonquail Turnix suscitator	PM	PM
Ruddy-breasted Crake Porzana fusca		WV
White-breasted Waterhen Amaurornis phoenicurus		R
Watercock Gallicrex cinerea		PM
Pheasant-tailed Jacana Hydrophasianas chirurgus		PM
Greater Painted-snipe Rostratula benghalensis		R/PM
Oriental Pratincole Glareola maldivarum		PM
Little Ringed Plover Charadrius dubius		R
Grey-headed Lapwing Vanellus cinereus*		WV
Northern Lapwing Vanellus vanellus		WV
Common Snipe Gallinago gallinago		WV
Pintail Snipe Gallinago stenura		WV
Swinhoe's Snipe Gallinago megala		PM
Wood Sandpiper Tringa glareola		PM/WV
Red Turtle Dove Streptopelia tranquebarica	WV
Spotted Dove Streptopelia chinensis	R
Plaintive Cuckoo Cacomantis merulinus	SV
Common Koel Eudynamys scolopacea	R/SV
Greater Coucal Centropus sinensis	R
White-throated Kingfisher Halcyon smyrnensis	SV	WV
Eurasian Hoopoe Upupa epops	WV
Barn Swallow Hirundo rustica	SV
Richard's Pipit Anthus richardi	WV	WV
Olive-backed Pipit Anthus hodgsoni	WV	WV
Red-throated Pipit Anthus cervinus	WV	WV
Buff-bellied Pipit Anthus rubescens		WV
Yellow Wagtail Motacilla flava		PM/WV
Grey Wagtail Motacilla cinerea		WV
White Wagtail Motacilla alba	WV	R/WV
Red-whiskered Bulbul Pycnonotus jocosus	R
Chinese Bulbul Pycnonotus sinensis	R	R
Sooty-headed Bulbul Pycnonotus aurigaster	R
Siberian Rubythroat Luscinia calliope	WV	WV
Bluethroat Luscinia svecica		WV
Daurian Redstart Phoenicurus auroreus	WV
Common Stonechat Saxicola *torquata*	WV	WV
Oriental Magpie Robin Copsychus saularis	R
Common Blackbird Turdus merula	WV
Japanese Bush Warbler Cettia diphone	WV	WV
Zitting Cisticola Cisticola juncidis	WV/PM	WV/PM
Plain Prinia Prinia inornata		R
Yellow-bellied Prinia Prinia flaviventris	R	R
Pallas's Grasshopper Warbler Locustella certhiola		PM
Lanceolated Warbler Locustella lanceolata		PM
Black-browed Reed Warbler Acrocephalus bistrigiceps		PM
Oriental Reed Warbler Acrocephalus orientalis		PM
Common Tailorbird Orthotomus sutorius	R
Dusky Warbler Phylloscopus fuscatus	WV	WV
Asian Brown Flycatcher Muscicapa dauurica	PM/WV
Masked Laughingthrush Garrulax perspicillatus	R
Great Tit Parus major	R
Japanese White-eye Zosterops japonica	R
Brown Shrike Lanius cristatus	PM	PM
Long-tailed Shrike Lanius schach	R	R
Black Drongo Dicrurus macrocercus	SV	SV
Common Magpie Pica pica	R
Red-billed Starling Sturnus sericeus*		WV
Purple-backed Starling Sturnus sturninus		PM
White-shouldered Starling Sturnus sinensis	SV	PM/SV
Common Starling Sturnus vulgaris		WV
White-checked Starling Sturnus cineraceus	WV	WV
Black-collared Starling Sturnus nigricollis	R	R
Crested Myna Acridotheres cristatellus	R	R
Eurasian Tree Sparrow Passer montanus	R
White-rumped Munia Lonchura striata	R
Scaly-breasted Munia Lonchura puctulata	R	R
Grey-capped Greenfinch Carduelis sinica	R
Common Rosefinch Carpodacus erythrinus	WV
Yellow-billed Grosbeak Euphona migratoria	WV
Black-faced Bunting Emberiza spodocephala	WV/PM	WV/PM
Japanese Yellow Bunting Emberiza sulphurata*		PM
Chestnut-eared Bunting Emberiza fucata	WV	WV
Little Bunting Emberiza pusilla	WV/PM	PM
Yellow-breasted Bunting Emberiza aureola	PM	PM
Crested Bunting Melophus lathami	WV

Appendix 2 Provisional priorities for conservation of farmland birds

Special feature: FOCUS ON FARMLANDS

Overview

BIRDS
What is agricultural land?

Special feature: FOCUS ON FARMLANDS

Overview

BIRDS What is agricultural land?

BIRDS
What is agricultural land?