3 The functional use of East Dongting Lake, China, by wintering geese ANTHONY D. FOX1, CAO LEI2*, MARK BARTER3, EILEEN C. REES4, RICHARD D. HEARN4, CONG PEI HAO2, WANG XIN2, ZHANG YONG2, DOU SONG TAO2 & SHAO XU FANG2 1Department of Wildlife Ecology and Biodiversity, National Environmental Research Institute, University of Aarhus, Kalø, Grenåvej 14, DK-8410 Rønde, Denmark. 2School of Life Science, University of Science and Technology of China, Hefei, Anhui 230026, PR China. 321 Chivalry Avenue, Glen Waverley, Victoria 3150, Australia. 4Wildfowl and Wetlands Trust, Slimbridge, Gloucestershire GL2 7BT, UK. *Correspondence author. E-mail: [email protected] Abstract A survey and study of geese wintering at the East Dongting Lake National Nature Reserve, China, in February 2008 revealed internationally important numbers of Lesser White-fronted Geese Anser erythropus, Greater White-fronted Geese Anser albifrons and Bean Geese Anser fabilis using the site, as well as small numbers of Greylag Geese Anser anser. Only five Swan Geese Anser cygnoides were recorded, compared with several hundreds in the 1990s. Globally important numbers of Lesser White-fronted Geese spend the majority of daylight hours feeding on short grassland and sedge meadows within the core reserve areas of the National Nature Reserve, and also roost there at night. Greater White-fronted Geese were not studied in detail, but showed similar behaviour. Large numbers of Bean Geese of both serrirostris and middendorffi races showed differing feeding strategies. The small numbers of serrirostris tended to roost and feed in or near the reserve on short grassland, as did small proportions of middendorffi. However, the majority of middendorffi slept within the confines of the reserve by day and flew out at dusk, to nocturnal feeding areas at least 40 km north on the far side of the Yangtze River, returning 40–80 min after first light. In order to safeguard these goose populations, it is essential to optimise the foraging opportunities for geese within the reserve and to understand the feeding habitats exploited by the geese in adjacent and remote areas such as those used by the middendorffi birds north of the Yangtze. Key words: Activity budgets, Bean Goose, East Dongting Lake, Greater White-fronted Goose, Greylag Goose, Lesser White-fronted Goose, Ramsar site management, Swan Goose. ©Wildfowl & Wetlands Trust Wildfowl (2008) 58: 3–19 4 The functional use of East Dongting Lake, China, by wintering geese Current knowledge suggests severe declines reedbeds (Phragmites sp.). However, before it amongst several goose populations in the is possible to consider appropriate East Asian Flyway (Syroechkovskiy 2006; conservation management actions in nature Wetlands International 2006). More precise reserves to maintain and potentially increase information on their abundance and their capacity to support geese at present distribution is lacking due to the challenges abundance levels, it is essential to of counting large numbers of wintering understand how birds utilise different sites simultaneously and to the shortage of wetland habitats within a wetland complex. skilled observer networks, especially in Furthermore, it is important to understand China, although the situation there is for which purposes these habitats are used improving. China is a key country because of throughout the diurnal cycle. For example, its importance for several wintering goose the presence of geese feeding in the vicinity species; it supports 98% of the global may enable other birds to sleep and use population of Swan Geese Anser cygnoides, open waters as a day-time roost in relative 100% of the flyway population of the safety, because the feeding birds are also globally threatened Lesser White-fronted vigilant for predators. Geese Anser erythropus (classified as In this account, we describe the results of vulnerable; International Union for a census of five different goose species using Conservation of Nature 2001), as well as a discrete area of the East Dongting Lake 80% of the Taiga Bean Goose Anser fabalis National Nature Reserve, designated by the middendorffi and 25% of Greater White- Chinese Government as a wetland of fronted Goose Anser albifrons populations in international importance under the Ramsar this flyway (Cao et al. 2008). Convention in 1992. Since large numbers of Despite the difficulty in obtaining geese occur at the site, diurnal activity accurate counts and thus in quantifying patterns were studied in further detail for the longer-term trends, it is important to two most numerous goose species to assess understand the causes of declines observed whether their use of the food supply and at specific goose wintering resorts in order resting areas on the reserve is competitive or to implement management actions where cooperative. By comparing the ways in which these are feasible. China has established a the geese utilise habitats within and outwith network of National Nature Reserves, this major Chinese wetland complex, we aim several of which are designated because of to describe key features of the site and their importance as wetland ecosystems and surrounding area that are critical for the to protect wintering waterfowl, including continued presence of each population. geese (BirdLife International 2004). Many of these reserves remain subject to intensive Study Area and often unsustainable human use in the The East Dongting Lake National Nature form of agriculture, forestry, fisheries, sand Reserve and Ramsar Site (29.32°N, 112.98°E) and gravel extraction, and other exploitation in Hunan Province, China, is an extremely such as the commercial harvesting of large (190,000 ha) area of shallow freshwater ©Wildfowl & Wetlands Trust Wildfowl (2008) 58: 3–19 The functional use of East Dongting Lake, China, by wintering geese 5 lakes, marshes and seasonally inundated water channels, extensive flats have been sedge meadows, which receives water from deposited, the higher and less frequently the upper and middle reaches of the Yangtze inundated of which support extensive River (Taylor et al. 2005). It forms part of the meadows dominated by a robust sedge more extensive Dongting Lake wetlands, an Carex sp. In the lower reaches, there are area of 500,000 ha, which is listed as an extensive areas of bare mud flats which are important bird area (IBA) because of its progressively exposed in the course of the importance for threatened species (including winter by water level recession and these Swan Goose and Lesser White-fronted become colonised by short ephemeral Goose) and for waterbirds occurring there in grasses. The reclaimed wetlands that lie large numbers (including Bean Goose and outside the dyke surrounding the lake are Greater White-fronted Goose) (BirdLife intensively cultivated with extensive areas of International 2004, Fig. 1). The IBA also rice, winter wheat and vegetables, and some includes West Dongting Lake and South areas of planted woodland. Dongting Lake, designated by the Chinese The wetlands and surrounding areas are Government as Ramsar Sites in 2002. Water state owned and were designated as a levels in the lake system rise and fall with National Nature Reserve in December 1984. those in the Yangtze River to the north, Fishing, reed harvesting and grazing (mostly fluctuating 16–18 m each year (Research goats and water buffalo) occur throughout Institute for Yangtze Water Resources the wetlands, but hunting is illegal and Protection 1999), although in recent years strictly controlled. this has reduced to 10–12 m (Y. Jiang pers. comm.). The climate is subtropical Methods monsoon, with an annual rainfall of 1.2–1.33 m per annum and mean temperature of Census 17°C, with frequent sub-zero temperatures Three teams of observers, on foot with in winter (Taylor et al. 2005). binoculars and 20–60x telescopes, The large annual variation in water levels attempted to count all the geese present in a has resulted in vegetation dominated by geographically defined area within the relatively few species, with common northwest core area of East Dongting Lake submergents (Vallisneria spiralis, Hydrilla on 16 February 2008. The survey covered verticillata, Ceratophyllum demeraum and Cai Sang Lake (a small lagoon behind the Potamogeton malainus), floating (Trapa sp., Nature Reserve Management Building but Nelumbo mucifera, Euryale ferox and Lemna not part of the reserve), and the area visible minor), and emergent aquatic vegetation from the road that runs on top of the dyke (Typha orientalis, T. angustifolia and Miscanthus confining the major part of the reserve, sacchariflorus) being prevalent at the site including Daxi Lake, Xiaoxi Lake and the (Research Institute for Yangtze Water adjacent areas of sedge beds (Fig. 1). These Resources Protection 1999). In areas of low are also the areas where goose activity sedimentation rates away from the main budgets were recorded (see page 7). ©Wildfowl & Wetlands Trust Wildfowl (2008) 58: 3–19 6 The functional use of East Dongting Lake, China, by wintering geese Figure 1. The study area within the East Dongting Lake Nature Reserve, China. ©Wildfowl & Wetlands Trust Wildfowl (2008) 58: 3–19 The functional use of East Dongting Lake, China, by wintering geese 7 Activity budgets Station. The dawn watches were carried out from two locations on 15 February Behavioural observations were made of the and from three locations on 18 February, two most numerous goose species at the from before first light (c. 06:00 h) until site, namely the Lesser White-fronted 08:30 h. Evening flight was observed at or Goose and the Taiga Bean Goose, from near the Management Station on the 12–19 February 2008. All birds in a flock evenings of 13, 14 and 17 February, from were scanned using a telescope, and the 16:30 h until after darkness (usually after behaviour of each individual on first being 18:30 h). Because of the dispersed nature encountered in the field of view was of these flights, the objective was to gather recorded (Altmann 1974). The behaviour data on the timing and direction of these categories were as follows: walk, feed, stand, flights, rather than to determine the total preen (including wing flap and other number of birds involved.