S42.3: Ecology and conservation of Black-necked Cranes Grus nigricollis

1International Crane Foundation, E-11376 Shady Lane Road, Baraboo, WI 53913, USA, e-mail fengshan.icf@baraboo.com; ²Pacific Northwest Research Station, USDA Forest Service, PO Box 1460, Cordova, AK 99574, USA, e-mail mbishop@eagle.ptialaska.net

The Black-necked Crane Grus nigricollis is the only high-altitude crane among the 15 species in the world. Its range covers 28–38^o N and 78–104^o E, stretching from the Altun and Kunlun Mountain ranges east to the Qilian and Wumeng Mountain ranges and south to Himalayas. Based on a coordinated winter count conducted during the 1991-1992 winter, the world population of Black-necked Cranes was estimated between 5,600-6,000, including 360 in the Kingdom of Bhutan, <10 in Arunachal Pradesh, and 1,300-1,600 in north-east Yunnan and western Guizhou, <100 in north-west Yunnan, 3,900 in south-central Tibet, and <20 in eastern Tibet of the People’s Republic of China (Bishop 1993, 1996). Since that count, unconfirmed sightings of small numbers have been reported from central Myanmar (T. H. Latt, Hlawga Park, Nature and Wildlife Division, Forestry Department, Ministry of Forestry, Union of Myanmar, pers. comm.), and northern Vietnam (G. Archibald, International Crane Foundation, PO Box 447, Baraboo, WI 53913, USA, pers. comm.).

Due to the geographic and political inaccessibility across much of its range, until the 1980s this species was the least known crane species. In the past 15 years, significant research and surveys have been conducted. Large wintering and breeding populations have been discovered in Tibet (Feng 1991, Dwyer et al. 1992, Bishop 1993) and northern Sichuan (Scott 1993, Yang 1991). And, winter habitat use has been studied in Guizhou (Li 1997) and south-central Tibet (Bishop 1996, M. Bishop and F. Li, International Crane Foundation, PO Box 447, Baraboo, WI 53913, USA, unpubl. ms.), and migration studies have been conducted in the eastern portion of its range (Wu et al. 1994).

The Black-necked Crane breeds across the Qinghai-Tibetan Plateau in the People’s Republic of China and Ladakh, India. Known breeding areas are relatively concentrated in three areas: central and western Tibet, eastern Qinghai, and north central Sichuan (Fig. 1). In Tibet, breeding surveys (May through mid-October) were conducted in 1987, 1988 (Feng 1991) and 1991 (Dwyer et al. 1992) primarily in and around two major east-west road systems: between Rutog in western Tibet and Nagqu in central Tibet, and between Rutog and Lhaze in south central Tibet (Table 1). Nests, chick, or pairs were observed in almost all counties in this area. In Qinghai Province, at least 22 known and suspected breeding sites from 16 counties have been documented (Lu et al. 1980; Guo 1981; Lu 1986; Yao 1982). Of these, Longbaotan, Nomhon, Bayinguoluohe, and Elinghu/Heihe are the four main breeding grounds (Yao 1982; Z. Wu and D. Li, Guizhou Institute of Biology, Guiyang, Guizhou, PR China 550000, unpublished data). In north central Sichuan on the southeastern edge of the Qinghai-Tibetan Plateau, Ruoergai Marsh (also known as Songpan Marsh) hosts some of the highest breeding concentration areas of Black-necked Cranes. A total of 239 cranes were sighted in summer of 1991 (Yang 1991, Scott 1993), with the majority of cranes occurring in Duoma, Tangke, and Lame of Ruoergai County, and Wachie and Longriba of Hongyuan County.

Two other provinces in China, Gansu and Xinjiang, along with Ladakh India have also recorded breeding Black-necked Cranes. Breeding areas of Black-necked Cranes in Luqu and Maqu counties of Gansu Province are part of Ruoergai Marsh. In Xinjiang, 12 Black-necked Cranes (11 family birds and one single bird) were sighted in September of 1991 at Yixiekepati Lake in Altun Mountains (Zhang 1992). In eastern Ladakh a small breeding population of <40 birds occurs (Pfister 1998).

Based on work by Guo (1981) and Li (1986), the breeding habitat on the Qinghai-Tibetan Plateau may be classified into three categories: (1) alpine bog meadows, (2) lacustrine marshes, and (3) riverine marshes. Alpine bog meadow is the most common wetland type in the headwaters of the major rivers found on the eastern and northeastern fringes of the Tibetan Plateau. These rivers include Jinsha Jiang (Yangtze River), Huang He (Yellow River), Nu Jiang (Salween), and Lancang Jiang (Mekong; Li 1986). Alpine bog meadows range in elevation from 3,400 m above sea level (Ruoergai Marsh, Sichuan) to 4,900 m (Xainza, Tibet; Wu and Li, Guizhou Institute of Biology, Guiyang, Guizhou, PR China 550000, unpublished data). Many of these wetlands occur in open valleys, basins, and flat lands that are poorly drained and/or have a permafrost layer. Annual precipitation is usually >400 mm, with glacier and winter snowmelt also providing major sources of water.

Lacustrine marsh is distributed widely at numerous fresh and saline lakes, especially in central and western Tibet (Feng 1991, Dwyer et al. 1992). The Black-necked Cranes breed in lacustrine reed marshes as low as 2,600 m above sea level (Nomhon, Qinghai) to 4,900 m (Xianza, Tibet). During 1991 studies in Tibet, breeding densities were highest in freshwater lacustrine marsh habitats (Dwyer et al. 1992). Open riverine marsh is found primarily at the oxbows and floodplains of several large rivers in Qinghai, central and western Tibet, and Ladakh’s Indus River.

There have been few studies on the food habits of breeding Black-necked cranes. Vegetation, including Lloydia filiformis and Potentilla anserina have been observed in droppings and stomach contents. (Lu et al. 1980; Li and Zhou 1985). Several lizards were found in the stomach of one Black-necked Crane at Qaidam (Guo 1981). Few observations have been recorded on food fed to chicks. In Ladakh, Pfister (1998) reported that chicks were predominantly fed insects, other invertebrates and plant tubers.

Nests are often close to slow-running streams, and are located on small grassy islands, island-like mounds, or are built directly in the water from mud, and surrounding vegetation (Nurbu 1985; Wang et al. 1989, 1991; Dwyer et al. 1992; Pfister 1998). Egg laying occurs primarily from the end of April through the end of June, with mid to late May the peak egg laying period (Wang et al. 1989; Dwyer et al. 1992; Pfister 1998). Re-nesting attempts have been observed as late as 13 July (Dwyer et al. 1992).

Usually two eggs are laid and hatch within 30-33 days (Lu 1986). Male and female alternate incubation duties. Nest building behaviour occurs throughout incubation, however, as incubation progresses, nest building (or repairing) behaviour is gradually reduced (F. Li and J. Ma, International Crane Foundation, PO Box 447, Baraboo, WI 53913, USA, pers. comm.). Cranes are fiercely territorial during the nesting and incubation period. When intruders approach the nest, cranes will attempt to lure them away. Territorial size varies depending upon individual birds, type of habitat, and breeding stage (F. Li and J. Ma, International Crane Foundation, PO Box 447, Baraboo, WI 53913, USA, pers. comm.; Li and Zhou 1985).

There is little information on the status of breeding habitat. Human population growth throughout the breeding range and the end of the commune system have increased pressure on both upland and wetland resources, especially in the form of grazing and agriculture (Dwyer et al. 1992). Overgrazing by domestic livestock in marsh areas degrades breeding habitats and, together with the increased human presence, likely disturbs breeding cranes. At Ruoergai marsh, an estimated 1,400 km² have been drained or altered for pastureland (Yang 1991). Numbers of livestock have been increasing resulting in over-grazing and the encroachment of livestock in high altitude meadows and marshes. Illegal hunting, egg collecting, and intensive use of pesticides have also impacted this area. Although there are no tangible impacts on Black-necked Cranes from peat mining south of Ruoergai marsh, potential threats exist including excessive mining and lack of wetland mitigation (Yang 1991).

In other breeding areas, egg collection and feral dogs are also important threats. In Xinjiang Province in western China, the Uigur nomads in the Altun Mountains Nature Reserve collect eggs from crane nests in early summer each year (Zhang 1992). Feral dog predation on eggs and chicks has severely affected small breeding populations in Ladakh (R. Chacho, A. 301, Spartan Heights, 16 Richmond Road, Bangalore 560 025, India 215304, pers. comm.; Pfister 1998).

The Black-necked Crane winters primarily in four areas: northwest Yunnan, northeast Yunnan/western Guizhou, Yarlung Tsangpo (river) valley and its tributaries of south-central Tibet, and in central Bhutan. Small numbers of wintering cranes may also winter in Vietnam and Myanmar.

While reliable counts are not available, we estimate that <100 cranes currently winter in northwest Yunnan, including approximately 80 at Napahai, a freshwater lacustrine wetland. Black-necked Cranes historically wintered at several areas in northwest Yunnan (Table 2). However, Lashihai and Caohai Lake of Heqing County have not reported cranes for several years (Wang and Wu 1986; Wei et al. 1994; Han 1995). At Luguhu, Yongxuan, and Niqiugou only small numbers of cranes (10-30) have been sighted sporadically since the early 1980’s (Han 1995; Li 1996).

Numbers of cranes wintering at Napahai have declined precipitously the past few decades. Before the 1960’s, an estimated 700-800 Black-necked Cranes wintered there (Yunnan Forestry Department, Kunming, Yunnan, PR China 650000, unpublished data). In 1968-69 an outlet cave was enlarged and much of the wetland was drained for pastureland, destroying the cranes’ food resources (Yunnan Forestry Department, Kunming, Yunnan, PR China 650000, unpublished data). By 1978-79 winter, numbers declined to about 300 cranes and by 1981winter only 60 -70 birds remained. Further exaggerating this decline at Napahai was the loss of birds to hunting by local military and government agencies (Yunnan Forestry Department, Kunming, Yunnan, PR China 650000, unpublished data). Cranes at Napahai may temporarily move outside to Bitahai, 25 km away, or other suitable areas. Bitahai is a deep, narrow marsh surrounding by dense forests and serves primarily as a fall staging area during October and November for Black-necked Cranes and waterfowl (e.g. Tadorna ferruginea and Tadorna tadorna; Yunnan Forestry Department, Kunming, Yunnan, PR China 650000, unpublished data).

This region includes wintering areas in northeast Yunnan and Cao Hai of Weining County of western Guizhou. on the Yunnan-Guizhou Plateau. The total population of Black-necked Cranes in this region is estimated to be 1300-1600 (Bishop 1996). There are five major wintering grounds: Cao Hai, Dashanbao, Daqiao Reservoir, Changhaizi Reservoir, and Xundian (Li et al. in press). Distances between wintering areas in the region are about 50-80 km.

Of all the wintering areas in northeast Yunnan and western Guizhou, Cao Hai has the most complete winter counts, with >25 years data. Throughout the years, population fluctuations have corresponded with local land-use events (Li 1997). In recent years, a stable population of over 400 Black-necked Cranes have wintered at Cao Hai. Approximately 50 km west of Cao Hai, is Chuandonghaizi of Niupeng Xiang of Weining County, a historical wintering area for many Common Cranes Grus grus and some Black-necked Cranes. The wetland surrounding the lake, however, has been almost totally reclaimed by local farmers. In 1995 only 4 Black-necked Cranes and 110 Common Cranes were observed at this site (J. Harris, International Crane Foundation, PO Box 447, Baraboo, WI 53913, USA).

In northeast Yunnan cranes have been observed at 17 sites scattered over 6 counties (Table 2; Li et al. in press). During the 1995-96 winter, 77% (1,340) of the cranes in northeast Yunnan occurred at four sites: Dashanbao, Daqiao, Changhaizi, and Xundian (Yang 1997). Similar to northwest Yunnan, the total number of Black-necked Cranes wintering in this region varies annually and counts are often unreliable. Unless a coordinated roost count is conducted and observers are equipped with good binoculars and spotting scopes, the total number of Black-necked Cranes in northeast Yunnan is likely to remain a mystery (Li et al. in press).

Black-necked Cranes winter mainly in the middle reaches of Yarlung Tsangpo (river), and in the valleys of Lhasa and Nyang Rivers. Cranes occur from Lhaze east to Nedong on the Yarlung Tsangpo, north to Maizhokunggar on the Lhasa River and south to Gyantse. During a 1991-1992 winter count, approximately 3,900 Black-necked Cranes were observed; accounting for at least 65% of the world population (Bishop 1993). While only limited surveys have been conducted in eastern Tibet, <20 cranes are estimated to winter in this area. To date, cranes have been observed in Nyingchi and Gongbogyamda Counties (M. Bishop et al., USDA Forest Service, PO Box 1460, Cordova, AK 99574, unpubl. ms.; Ciduo, Tibet Plateau Institute of Biology, 230 Beijing West Road, Lhasa, Tibet, PR China 85001, pers. comm.).

There are three wintering areas in Bhutan: Phobjikha/Khotokha, Bumdiling, and Bumthang. Wintering populations in Bhutan appear to be increasing. During the 1991-92 winter, 315 cranes were counted at the three sites (Bishop 1993). By 1997-98 winter numbers increased to 414 cranes (G. Archibald, International Crane Foundation, PO Box 447, Baraboo, WI 53913, USA, pers. comm.).

Two broad categories are classified for crane wintering areas: lacustrine marsh, and river valleys (Li et al. 1988). In south central Tibet and Bhutan, cranes are found in river valleys, whereas in northwest Yunnan, northeast Yunnan/western Guizhou they winter in lacustrine marshes. Intensive studies on habitat use and selection by Black-necked Cranes has been undertaken in northeast Yunnan/western Guizhou, and in south central Tibet. The following information on habitat use and selection is mainly from the studies from these two areas.

In northeast Yunnan/western Guizhou, most wintering areas are reservoir wetlands. These reservoirs were constructed primarily in 1958 when Mao's Great Leap Forward was initiated (Li 1997). Cranes in northeast Yunnan are scattered, probably a result of limited wetland habitats. Cranes forage primarily in pasture and crop fields. Cao Hai remains the largest wetland area with relatively high concentration of cranes. Although cranes at Cao Hai are seen foraging in all types of habitats in the lake basin, and occasionally on the upland farmland, there is a great reliance by cranes on wetland habitats, ranging from roosting sites to foraging habitats. Deep water cannot be used by cranes although it contains both plant and animal foods.

At Cao Hai, all roosting sites were in the shallow water along the lake edge. Shallow water areas are all located in bays sheltered from wind and have large areas of marsh between the shallow water and farm fields. Shallow water and adjacent sedge meadow serve as barriers that prevent terrestrial predators from gaining access to the roost sites. Foraging cranes have a larger range of movement and use a greater variety of habitats than do roosting cranes. Cranes at Cao Hai forage in shallow water marsh, sedge meadow, grassland, non-vegetable farmland, vegetable field, upland crop fields, and ditches, but they prefer most sedge meadow and least crop fields (Li 1997).

Throughout their Tibetan wintering grounds, during the day Black-necked Cranes are found most often in agricultural fields (primarily harvested barley and spring wheat), followed by pastureland and riverine habitats. Cranes roost on the edge of large reservoirs and in the slower moving waters of the smaller channels of the Lhasa and Yarlung Rivers, and on some of their major tributaries, such as the Re River in Lhaze County (M. Bishop et al., USDA Forest Service, PO Box 1460, Cordova, AK 99574, unpubl. ms.).

Food habits of Black-necked Cranes wintering at Cao Hai and south central Tibet were studied. A total of 47 species of plant were found in the faeces of Black-necked Cranes wintering at Cao Hai. Of these, 38 were species native to the reserve and nine were crops (e.g. potato, corn, and Giant Vetch). Among the 38 native species, 25 were the aquatic plants (Li et al. 1997). In south central Tibet, cranes mainly forage in crop fields. More than 70% of the total materials detected in the faeces of Black-necked Cranes were grain crops, including barley, winter and spring wheat, indicating crops are the main food source for the Black-necked Cranes wintering in Tibet (M. Bishop and F. Li, I International Crane Foundation, PO Box 447, Baraboo, WI 53913, USA, unpubl. ms).

In winter, most Black-necked Cranes frequent large foraging and roosting flocks. A small number of pairs usually with chicks, however, establish feeding territories. The territories of Black-necked Cranes at Cao Hai in Guizhou have been observed only in wetlands (Li 1989) suggesting that freshwater lacustrine marsh is critical habitat in this area for crane families in this area. Territorial Black-necked Cranes roost by night with other cranes and usually leave the roost with non-territorial cranes in the early morning for adjacent farmland. Normally they return to their wetland territories between 0900 and 1000. In south central Tibet, families were noted on territories in agricultural fields, but joined roosting flocks (M. Bishop et al., USDA Forest Service, PO Box 1460, Cordova, AK 99574, unpubl. ms.). While territories are defended by Black-necked Cranes throughout the winter season, territory size decreases as winter progresses (Li 1989). Although they winter sympatrically with Black-necked Cranes in Yunnan and western Guizhou, Common Cranes Grus grus do not establish territories , possibly because they are physically weaker than Black-necked Cranes (Li 1989).

Loss and degradation of habitat due to increasing human population pressures are the principal threats to the species in its winter range (Bishop 1996). Wetland drainage and damming of wetlands have occurred at many wintering areas in Yunnan and Guizhou. Wetlands have been diminished to different extents in Lashihai of Lijiang, Lanniguo of Yongning Xiang of Ninglang county (Lu 1986) and at Napahai (Yunnan Forestry Department, Kunming, Yunnan, PR China 650000, unpublished data). At Cao Hai of Guizhou, the wetland was drained three times, during which cranes numbers declined correspondingly (Li 1997). In northeast Yunnan, most wintering areas are reservoir-type wetlands, built for irrigation. Reservoir construction has reduced the availability of shallow water areas needed for wading birds like cranes.

Losses of habitat, especially wetland habitats continue to occur throughout the south-central Tibet wintering area. Since the 1950’s extensive channelization along the Penbo and Nyang Rivers has hastened the loss of river floodplain and riverine wetlands. In addition, both Shigatse and Lhasa have experienced a high human population and economic growth accompanied with the loss of wetland habitats (Bishop et al. 1997). While cranes used to winter around Lhasa (Ludlow 1950), loss of wetlands and croplands to urbanisation has forced cranes to winter nearby at Doilungdeqen area (M. Bishop et al., USDA Forest Service, PO Box 1460, Cordova, AK 99574, unpubl. ms.).

Black-necked Cranes have also been affected by changing agricultural practices in south central Tibet and northeast Yunnan. With the increased emphasis on fall plowing to control insects and on cultivation of winter wheat for its high yields, less waste grain and other residue are available on the surface for the cranes to glean. At the same time, decreased residue and waste grain may intensify crane depredation on the winter wheat seedlings. In northeast Yunnan, many areas have been assigned as Sheep Breeding Bases, where non-native grasses have been planted extensively. In these areas, cranes use is very scattered, with most foraging occurring on the hilly uplands (Li et al. in press).

Deforestation has been destructive at Cao Hai Lake in Guizhou and at Napahai, Yunnan. Before the 1950s, the mountains around Cao Hai lake were covered with forest. Development of Shuicheng, a mining industrial city about 80 km from Cao Hai, and the Great Leap Forward (1958) destroyed almost all forest at Cao Hai as well as in other areas. Further felling led to a drop in forest coverage around Cao Hai from 35.8% in 1956 to 13.7% in 1982. Soil erosion resulting from deforestation has become one of the most serious factors threatening the Cao Hai lake and its wetlands. A similar situation happened at Napahai Yunnan. During the 1950’s a county timber company (now with 3,000 employees) run by the provincial forestry department, was established at Xiaozhongdian about 10 miles from Napahai. Today, Napahai and adjacent areas have been clear-cut and thousands of the company employees have been laid off due to lack of available timber resources.

As described earlier, there are four main wintering grounds of Black-necked Cranes. All are located south or southeast of the breeding grounds; therefore, migration routes for Black-necked Cranes basically follow a south-north direction. Three migration routes of Black-necked Cranes have been suggested by Wu et al. (1994).

Eastern Route -- The cranes summering in Ruoergai Marsh are inferred to migrate south along Qionglai mountains and Min Jiang (river), through Ya’an, Leshan, Rongxian, and Yibin before arriving at Wumeng Shan region. Cranes remain in Ruoergai Marsh for about 170 days, and in Wumeng Shan Region for about 150 days, indicating a month-long spring and fall migration between these two areas. In support of this theory, two cranes banded in Ruoergai Marsh were sighted at Cao Hai (Wu et al. 1994), and two birds were collected at Ya’an (Schafer 1939, referred from Li 1986) and at nearby Rongxian (Li 1986).

Central Route -- Cranes summering in Longbaotan, Qinghai Province, are inferred to migrate along Tongtian He and Jinsha Jiang (both the Yangtze River), Queershan Mountain, and Shaluli Shan mountain, passing through Shiqu, Garze, Litang of western Sichuan before arriving to the Hengduan Shan region of northwest Yunnan. One crane banded in Longbaotan was relocated at Napahai, a distance of approximately 800-km. And, along this proposed migratory route, cranes have been observed historically at Litang (Dolan 1939, Schafer 1938), and occur presently at Garze during October and March (Lu 1986).

Western Route -- The western route was hypothesised by Wu et al. (1994) for cranes breeding in southeastern Xinjiang , western Qinghai, central and western Tibet. They theorised that these cranes winter in the middle Yarlung Tsangpo valley, with some crossing the Himalayas and wintering in Bhutan.

In general, we know little about populations and habitat status of breeding Black-necked Cranes, especially in northwest and southwest Qinghai. More investigations on the breeding grounds of Black-necked Cranes in these areas are needed. At the same time, Black-necked Crane migration, including use of stopover areas, needs to be studied. Due to geographic inaccessibility across much of its range, advanced techniques, such as satellite tracking, should be employed for migration studies.

Wetlands, including lake and reservoir edges, riverbanks, and bog meadows, are the only suitable roosting and nesting habitats for Black-necked Cranes. Depending on time of year and location, wetlands are often the preferred foraging habitat. Maintenance of high quality and quantity of wetland in both wintering and breeding areas is the key to for the long-term survival of this species.

Food availability for different types of land use should be studied to determine which habitats have the high food abundance. At the same time, agricultural practices in the wintering areas should be carefully planned in consideration the need for Black-necked Cranes. In areas where crop depredation is a problem, it might be cost effective to lease a certain amount of croplands. For example, if depredation on winter wheat becomes a problem in Tibet, waste barley and spring wheat fields could be leased every winter to relieve pressure on the winter wheat fields. Fields left with waste grain away from the road would allow for cranes to be undisturbed by any traffic, and would be less noticeable to humans.

Besides the ecological and biological aspects of the Black-necked Crane and its habitats, there also exist economic, social and cultural diversity of its human inhabitants. Conservation measures will be more effective and most likely to be successful if the measures are planned with consideration for compatibility with the diversity of culture and social aspects in this region.

We wish to thank J. Harris and Dr. G. W. Archibald for reviewing the manuscript.

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Table 1. Known and unconfirmed { } breeding areas of Black-necked Cranes in China.