The Chinese don't hang about. We are back working with colleagues at Chongming Dongtan National Nature Reserve 9 months after our last visit. In that time, 27 km of new 8 m high sea wall had been almost completed and a series of sluices (water gates -top photo) were under construction. We are back to discuss the finer details of the snappily named Bird Habitat Optimisation Project. Chongming Dongtan is located in the mouth of the Yangtze River and is a major staging post for waders on the East Asian-Australasian flyway, particularly important for Great Knot, Far Eastern Curlew and Nordmann’s Greenshank.
The project aims to firstly eradicate, by cutting and flooding, invasive non-native Spartina alterniflora that has spread across 16 km2 of mudflats, and secondly, to create habitats to support the priority species within the 25 km2 project area; waders, wildfowl, cranes and reedbed specialists such as Reed Parrotbill. The current visit provides an opportunity to assess the breeding birds of the reserve. Apart from the star turn, the Reed Parrotbill, the reedbeds support large numbers of Oriental Reed Warblers, which in turn are the host for large numbers of Eurasian Cuckoo (but more of this story in a later post). Herons are another key group, with large numbers of Yellow Bittern as well as egrets, Purple Heron and Night Heron. We found enough Cinnamon Bitterns to suggest they are breeding in good numbers and also added Schrenck's Bittern, which may also be breeding, to the reserve list. Whiskered Tern and Pheasant-tailed Jacana are found on the pools and a selection of waders breed, including Grey-headed Lapwing, Black-winged Stilt and Kentish Plover. Views of Slaty-breasted Rail and another small crake, supposedly out of range, suggest there is more to find out about the reserve. One small issue is that the newly arrived Spartina now supports it's own bird community, including the scarce Marsh Grassbird, although this is now considered to be fairly widespread in China. It is certainly numerous at Chongming; it's fluttering display flight and twirly song evident throughout.
Autumn passage is just underway. Greenshank, Red-necked Stint, Marsh Sandpiper, Far Eastern Curlew and Oriental Pratincole are the fore-runners of a deluge of waders later in the coming months. The week progresses and we discuss water regimes, salinity, salt marsh restoration, the benthic fauna and species requirements. Slowly, a detailed management programme comes together. Islands, channels and pools are shaped and located by the ecologists and passed on to the engineers to do the 'cut and fill' maths. The digital projector displays continually changing topographical maps until we reach the final design. Where will spring passage waders feed? Can we create roosting areas for Great Knot? Will that cater for Spot-billed Ducks? What water depths will deter the crabs from predating the Reed Warblers? Where will we aim to establish a new colony of egrets? How to entice Saunders' Gull to nest. What does Spoon-billed Sandpiper feed on?
Between workshops, we sampled most of the inhabitants of the reserve area; big fish, small fish, poison fish, gobies, mudskippers, freshwater shrimps, brackish shrimps, jellyfish, big clams, small clams, razor clams, winkles, crayfish, crabs, duck soup and ducks tongues. Delicious they were too!
Photos; above - water gate, the perimeter ditch (!), presenting designs.Below - Grey-tailed Tattler, Red-necked Stint, Yellow Bittern, Sharp-tailed Sandpiper.