Wednesday, 3 February 2016

Hooded Cranes

Chongming Dongtan is one of the most important wintering sites in China for Hooded Cranes, with the majority of the population wintering in Japan at one site, Izumi.  It is a threatened and declining species with a global population of around 11,000 birds.  At Chongming Dongtan, it winters primarily on the saltmarsh.  Sea Bulrush Scirpus mariqueter is a dominant species in the saltmarsh vegetation; and its corms and seeds form a major food source for the cranes (and other wintering waterbirds such as Tundra Swan).  One study showed that the corms and rhizomes composed about 99% of the total food content of the cranes.  

The corms in the outer saltmarsh zone (far from the seawall) are easier to find by the cranes as they are buried underground shallower than those in the inner zone due to daily erosion by tidewater. So, for easy access to food, Hooded Crane tended to select the regions near the channels at low tide as their foraging habitat.  Despite the similar food content between Hooded Crane and Tundra Swan, obvious ecological separation occurs in their foraging behaviour, foraging times and foraging habitats.  

However, the native Scirpus mariqueter dominated tidal vegetation is highly threatened and diminishing rapidly.   Land reclamation is a major threat all along the Chinese coast but the native vegetation is also being out-competed by the non-native Smooth Cord-grass Spartina alterniflora  (the eradication of which is the focus of our project at Chongming).  Human activities such as fishing, and notably eel fishing at Chongming Dongtan, have resulted in serious disturbance to the Hooded Crane and other waterbirds.  Although the cranes continue to focus their activity on the remaining good quality saltmarsh, they now also increasingly feed in rice paddies just over the sea wall, particularly at high tide.  One of the reserve projects at Chongming is to create ‘sacrificial’ rice paddies in safe locations for the benefit of the cranes and other waterbirds.

We found a mixed flock of 70 Hooded and 18 Common Cranes loafing and displaying on the upper areas of the saltmarsh.  Interestingly, there was one family of apparent hybrid Hooded x Common Cranes, a not infrequent occurrence.  These birds displayed the bulk and general colour of the Commons but had a washed-out Hooded head pattern.

Pics- above: Hooded Cranes (with Common Crane in the background).
Below: cranes on the salt marsh with distant fishing boats and bouys, displaying Hooded and Common Cranes with some hybrids in the foreground.

Monday, 25 January 2016

A quick trip to China

Winter birding at Chongming Dongtan in China is like a good UK winter and a mega autumn rolled into one.  You get huge numbers of ducks and geese along with stripey warblers and pipits. This was my fourth visit to Chongming, with one trip in each season.  We were back for a weeks stay at the ‘eco-village’ with a mixed programme of site checking, report writing and presentations. The aim was to prepare a management and monitoring plan for the nature reserve and its new habitats that are now appearing as a result of the Bird Habitat Optimisation Project.  Just to remind you, the project is to eliminate 16 km2 of invasive Cord-grass Spartina alternifolia and then create 25 km2 of wetland habitat, mainly lagoons and reedbeds.  After the design and build phase, with contractors being on site for the last 2 years, the lagoons are now taking shape and the Spartina is being cut and flooded.

Pallas's and Yellow-browed Warblers, Red-flanked Bluetails and Daurian Redstarts flit around the village gardens while we work.  The early morning walks around the fields beyond the village gate reveal hundreds of Red-throated, Water and Buff-bellied Pipits with Rustic, Black-faced and Pallas's Reed Bunting.

Back to the plan.  The target species are Reed Parrotbill, Hooded Crane, Tundra Swan, Great Knot, Far Eastern Curlew, Spoon-billed Sandpipers, Nordmann's Greenshank, Black-faced Spoonbills and Saunders’s Gull. Weeks of reading everything published on these species ends up getting distilled into the plan.  How do we create and maintain suitable feeding, breeding, roosting habitat for the key species?

Out to section A of the reserve to check the newly created reedbed pools and ditches.  Snipe ping away, Reed Parrotbills noisily crunch through reed stems to find their scale bug dinners and Chinese Penduline Tits swirl around in flocks.  Dusky Warblers and Bluethroats hop around the reed bottoms.  The lagoons support hundreds of wildfowl: Spot-billed Duck, Pochard, Pintail, Falcated Duck, Goosander and Goldeneye.  Two separate sections of the reserve will be managed by WWF and The Nature Conservancy (TNC).  Both are currently developing visitor and educational facilities. A high five moment as the roosting islands we had created in front of the proposed WWF viewpoint had ....roosting waders.  Eighty Black-faced Spoonbills loafed in front of the TNC visitor centre as we arrived but they rapidly took flight to find a quieter area.  A bit more screening required perhaps.  

Final presentations done and report crunched, we headed back out to the saltmarsh to find the wintering Tundra Bean Geese, Hooded and Common Cranes. In the duller moments, the flocks of gulls kept us going and seemed to contain Mongolian, Heuglin's, Slaty-backed and Saunders’s. Being an ecologist is not such a bad job at times.

Photos: top - from design (lower) to habitat on the ground (top)
Below - Black-faced Spoonbills, Chinese Penduline Tit, Red-throated Pipit, Pallas's Warbler.

Monday, 4 January 2016

Wallasea - a wetland designed for the future

The RSPB’s wetland creation project at Wallasea Island in Essex has been much in the news over the last year.  In July, the first phase of the intertidal habitat was completed and the sea wall breached.  On completion of all five phases of this innovative and forward-looking project, around 700 hectares of saline to fresh water habitats will have been created.

The project aims to combat the threats from climate change and coastal flooding by recreating a wetland landscape of mudflats and saltmarsh, lagoons and pasture.  It will also help to compensate for the loss of tidal habitats elsewhere. Habitat design will look to accommodate colonizing species from the south.  Much of this design is difficult to see at ground level but the aerial photograph above shows many of the habitat features incorporated into the design.  This is what can be seen:

A – This will be the visitor hub in the future.  Immediately adjacent are three shallow saline lagoons that will be managed for passage and breeding waders (top photo below).  They will be rotationally dried and flooded to maximize their food supply.  They will provide ideal conditions for Black-winged Stilts.

B – The entrance to the reserve will be through an area of saltmarsh saline creaks with shallow pools, suitable for a range of specialist invertebrates.

C – Shallow saline lagoon with islands and seasonal brackish pools suitable for breeding birds and a range of characteristic flora and fauna.  The conditions will be suitable for species currently more frequent to the south and that are likely to move northwards.

D – Seasonally drying salt pan, for Kentish Plovers with a bit of luck.

E – Freshwater marsh and grassland with pools and ditches for breeding waders.  These areas will be protected from mammalian predators by a barrier fence built into the surrounding ditches (see photo below).

F – Rough grass and wild-bird cover around the margins of the wetland will provide habitat for small mammals, reptiles and invertebrates.  The photo shows the mosaic cutting pattern to increase the structural diversity of the rough grassland. This will also benefit birds of prey such as harriers and owls.

G – An area of regulated tidal exchange with numerous islands, where water levels can be controlled (see sluice photo below) for the benefit of breeding, passage and wintering waterbirds.

H – The inter-tidal area has numerous features designed into it, including shallow lagoons that will provide the ideal feeding conditions and food resource for Spoonbills.  Once fed-up and in the mood, higher islands with scrub have been provided for the Spoonbills for nesting.

I – The range of islands provided includes some with shingle, sand and cockle-shells for nesting terns (hopefully Little Tern) and Ringed Plovers.  Will it all work?  We shall see.

Saturday, 5 December 2015

Review and rejuvenate

The work diary is filled with Annual Reviews at the moment; a yearly assessment of how each nature reserve is performing against its habitat and species targets.  Two of the top 12 wetland reserves in the UK for waterbirds were recently visited for a review: Berney Marshes/Breydon Water and the Ouse Washes.

Rejuvenation of key areas of habitat by a careful bit of ‘disturbance’ turned out to be a dominant theme for both sites.  Nature reserves can become rather ‘tired’ over a number of years as habitats become rather stable under routine management operations and the actions of natural succession.  Early succession wetland habitats in particular can become overgrown as invasive swamp species begin to dominate what were previously bare muddy areas with annual plants.  In many habitats, a degree of disturbance can knock back the succession and open up opportunities for a greater variety of species to flourish again.  This disturbance through management is seeking to mimic natural events such as flood and drought.  

Berney Marshes recorded a peak of over 91,000 waterbirds last winter and over 200 pairs of waders bred in the spring.  Increasing areas of rough grassland are being retained around the reserve; last year it also had up to 5 Rough-legged Buzzards and 16 Short-eared Owls.  However, the ditches and floods within the wet grasslands are the key feature of the reserve and increasing amounts of Sea Club-rush can become a problem in these areas as the grazing animals avoid eating it.  Staff at Berney have been drying out, cutting and rotovating areas of club-rush with great success, allowing re-colonisation of the resultant muddy ground on re-flooding by annual plants that provide abundant food for wildfowl. The newly flooded pools were covered with hundreds of Lapwing, Wigeon and Teal.  New projects currently being planned on the reserve will deliver significantly more scrape and lagoon habitat alongside Breydon Water for the benefit of terns, Avocets and passage waders.

The Ouse Washes has been suffering for a number of years from increasingly frequent summer flooding, resulting in a sharp decline in breeding waders as nests are washed out.  As a result, conservation work in recent years has been directed at creating habitat outside of the washes.  This year, the so called ‘Pilot Project’ the initial trial of creating wet grassland habitat for breeding waders on ex-farmland adjacent to the washes, held an amazing 174 pairs of waders on 76 ha.  The dry summer this year also allowed some increase in the waders on the main washes. The ‘crake-ometer’ accurately reflected the dry summer conditions: Corncrakes increased to 3 or 4 while the wet-loving Spotted Crakes were absent.  The fenland Cranes are increasingly finding the washes to their liking with up to 21 present at the moment.  Scrapes and floods grow over quickly on the Washes so the dry conditions have allowed a considerable amount of restorative habitat work to be undertaken.  New scrapes have been created and chisel ploughing has opened up compacted soils to the delight of feeding Snipe.  This work will significantly benefit waders and waterfowl in the coming breeding season – if the rains stay away.

Photos: above Wigeon and Club-rush rotovation at Berney. Below: wildfowl and new scrapes at the Ouse Washes.