The Black Death – try an eco-remedy

Cormorant - a skilled fisherman that avoids paying the entrance fee, East Warwick gulls, Eider!

I was once escorted out of a fishery conference for suggesting that anglers use Cormorants as a scapegoat for bad fishery management. A trip down to Walthamstow Reservoirs reminded me of the Cormorant-fish controversy, the bird anglers like to call the ‘Black Death’ and claim wipes out fish stocks. Now there is some truth to this complaint in some situations – on many a simple fishery, the Cormorants will be able to simply catch the fish without much effort.  Surely it wasn’t the clearest of thinking to establish a trout fishery on a concrete puddle that had a Cormorant roost in the middle!  Despite this, situations are not always as clear as they seem; most Cormorants nesting at Walthamstow do not fish on site.  I’ve always believed that birders and anglers should be on the same side – we both want to see healthy wetlands.  And the starting point for a solution should be to look at these healthy natural wetlands, particularly the complexity of the underwater habitat.  Provide fish with refuge areas and they will be less easy to catch.  Variation in the topography of the lake bottom, the addition of underwater reefs in the form of fallen trees, rocks or islands of aquatic vegetation, have all been shown to help. These are standard measures that conservationists will employ in creating a new wetland.  But instead of improving fish habitat, the average fishery manager too often rushes for the shotgun and chainsaw.

A second issue at Walthamstow is the apparent decline of breeding duck. In what seemed a good idea at the time (Thames Water have a history of good conservation staff), the formerly scrubby island on the East Warwick was cleared and re-formed, in order to try and create a better habitat for waders and duck. Unfortunately, this did not foresee the surge inland of breeding Herring and Lesser Black-backed Gulls. The gulls took over the island, the duck departed. Predation by the gulls has clearly changed the distribution of breeding duck. Good management of the islands and marginal vegetation would seem to be central to solving the problem.

I first went to Walthamstow Reservoirs exactly 40 years ago. I missed a Shag, but got quite excited by a pair of Goldeneye. There were no roosting Cormorants (this started in 1972 I seem to remember). The first Trout went into No 5 in 1978. Today there were plenty of Cormorants (at least 142 active nests), 7 Ring-necked Parakeets and an Eider.

How big are your tussocks?

Brents at Old Hall - keep eating chaps.  Spot the Brant.

The ‘improved’ grass fields at Old Hall Marshes are managed to provide winter grazing for the internationally important numbers of Dark-bellied Brent Geese in the Blackwater Estuary. The fields are prepared to provide the lush sward of fine grasses the birds prefer to eat, with a target grass height of 50-100mm in October. The ‘by-product’ of a winter's grazing by geese and Wigeon is a tight, occasionally tussocky, short spring grassland that attracts nesting Lapwings. However, in recent years, Brent numbers locally have followed the national trend of decline. There has been less grazing in the fields, resulting in a spring grass height somewhat longer and poorer for Lapwings.

Today the sward measuring boots had an outing to the various fields at Old Hall. With reduced grazing and warmer winters, additional grazing may now be required to bring the spring sward into an ideal condition. Formerly fertilised, farm-yard manure is now added to the fields; the Dutch traditionally do this in late winter to bring earthworms towards the surface for the benefit of breeding waders such as Black-tailed Godwits.

Around 3,500 Brents have been using Old Hall of late, with around 18% of young birds suggesting a good breeding season in 2010. The flocks of Dark-bellied Brent today also harboured a Black Brant and a Pale-bellied Brent. Six white-fronted Geese were nearby. Displaying Marsh Harriers were continually in the air (up to 10 birds together), and Merlin, Peregrine, a couple of Ruff, Pintail, Scaup, Bearded Tit and a few of the recently recorded 1,800 Grey Plovers were amongst the mass of birds on offer today.

B-n G's

The William Girling - a bit like the sea but without sand, or salt, or sun, or birds (except B-n G's).

The William Girling Reservoir holds the largest wintering group of Black-necked Grebes in the UK. Yet this is not a bird-rich site. It is not especially favoured by diving duck, it is shunned by Shoveler, poo-pooed by Pochard and used principally as a dormitory by dabblers.  It is a concrete doughnut holding water.  But presumably the B-n G’s have some competitive edge here. Although there are occasional records from other sites in the Lee Valley, no other local site regularly holds wintering birds. The peak count on the Girling over the last ten years was of 32 birds in December 2007. Peak winter numbers have been around the mid-20s for the last three winters.

With 24 birds arriving on the reservoir in the first week of August last year, around this number of birds have remained all winter. Numbers are just beginning to drop as the first birds move off, 18 were still present today. Seven months on the Girling! What is there left to eat?

Black-necked Grebes are a specialised invertebrate feeder, principally seeking aquatic insects and their larvae by ‘gleaning’, although they may also take molluscs, crustaceans and small fish. They tend to favour shallower waters in the summer, moving to deeper, mainly coastal sites in winter. This concrete-edged basin with water depth of around 14 metres would seem to be at their edge of tolerance, with BWP stating diving depths of up to 5.5 metres for up to 50 seconds. Birds diving around the margins (where there are concrete ‘roads’ a metre or so down) stay under for 30-40 seconds, whilst those well away from the reservoir margins re-surfaced after 50-60 seconds. It would be fascinating to find out what they are feeding on. The other big question is where are they between February and August?

Target: higher water levels

Spring seemed just around the corner today, with glorious sunshine at last and reports of booming Bitterns coming in from the south-west.  So, with a trip down to Rainham Marshes, thoughts turned to maintaining ideal water levels through the coming breeding season.

A lot of work is happening at Rainham this winter, not least a review of the hydrology. Maintaining adequate water into the summer is a key issue; essential for providing good feeding conditions for breeding and passage birds.  Good work by the site staff over the winter has blocked some of the seepage points identified last autumn. The Target Pools look particularly good at the moment, with higher than usual water levels – but the test will come in the spring as water levels naturally drop. The overall aim should be to achieve a strategic approach to water level management, a succession of good feeding areas around the reserve through the year. Various trials involving moving water around the site should indicate if this is possible.

Yesterday's Penduline Tits failed to re-appear, but with good water levels the reserve was holding large numbers of birds, notably Lapwings, Wigeon and Teal, and of course gulls.  Meanwhile, back on the garden feeders, Mealies continue to feature; up to six amongst the 20+ redpolls.

La Ferme aux Grues

A weekend of birding around the lakes and woodlands of the Champagne region is the added bonus of needing to re-supply with enough fizz to last through the coming year’s celebrations. After filling the car boot, it’s on with the birding, and firstly into the woodlands.

Looking around the Oak and Hornbeam woodlands surrounding Lac du Der and at the Foret d’Orient, the contrast with English woodlands is immediate; the French manage their broad-leaves for a supply of firewood. Coppice clearings and woodpiles are everywhere, resulting in well-structured woodland habitat. Even on a murky, frosty morning we quickly found four species of woodpeckers including Middle-spotted and Black, as well as numerous Short-toed Treecreepers, Nuthatches, Firecrests, Hawfinch and both Willow and Marsh Tits.

Lac du Der, France’s largest artificial lake, was not at its most accommodating; an icy north-easterly blowing across the water. Dabbling duck were abundant, principally Mallard, Teal and Wigeon, with a few Shoveler and Pintail. Greylag Geese, wintering birds from Sweden, were everywhere, with 100+ White-fronts and a few Tundra Bean thrown in. Bewick's Swans numbered 50 or so, with Whoopers only slightly less numerous. At least 50 Great White Egrets were noted, mostly around the shallow pools and floods beyond the lake, but not a single Little Egret. Buzzard, Hen Harrier and Peregrine hunted around the lake.

The highlight of the afternoon is the arrival towards dusk of the Cranes as they gather to roost on the islands. They feed by day in family parties in maize and other stubbles in the surrounding countryside, although the normally productive feeding viewpoint at La Ferme aux Grues was surprisingly quiet.  By late afternoon they  join into large noisy flocks drifting in low over the lake banks towards the roost sites.  As hundreds gathered on one of the larger islands, a party of five Wild Boar scuttled through, scattering Cranes in all directions. By the time frozen fingers had almost snapped off, around 1,500 had assembled on the islands within our view.

Below: La Ferme aux Grues, Foret d'Orient, Cranes arriving at the roost, Lac du Der.

KP (3); the rejuvenation

Freezing fog and five Great White Egrets greeted us at Ham Wall as we met to review last year’s management. Overall a very satisfactory year with 8 Bittern nests, successful breeding of Little Bittern, attempted breeding by Great White Egret and a singing Savi's Warbler.

Reedbeds under conservation management have traditionally been managed by rotational cutting, with the objective of slowing natural succession. Even on a small site, such an objective is questionable, but with a site of over 200 ha, this is not a feasible option. So Ham Wall is the focus of a larger scale ‘reedbed rejuvenation’ project. Compartments of up to 20 ha will be 'perturbed' by holding at a lower water level for a number of years and reverted to grassland by a combination of cutting, burning and grazing. After maybe five years, the ground will be re-flooded to create a shallow wetland. Reeds will slowly re-colonise but the return to early successional habitat will attract large numbers of waders and waterfowl in the early years. The land will then be allowed to return to reedbed, with higher water levels, and continue through its succession. Compartments will be 'rejuvenated' on rotation in order to maintain the early stages of reedbed.

The wet, early successional reedbed will benefit Great White Egret (as well as a range of other species) and we hope breeding will become established. The Dutch population at the main breeding location in Oostvaardersplassen reached a record high of 154 pairs in 2010 after the creation of additional feeding habitat in the late 1990s. Similar habitat will be created at Ham Wall.

In defence of the single goose

Why do the words ‘of unknown origin’ seem to follow every report of a single ‘wild’ goose? Single geese have had a rough deal for as long as I can remember, usually being relegated to the ‘escapes section’ of the bird report without much thought.  Clearly some individuals do have a captive origin, but the occurrence of these single geese seems to better reflect their national status rather than the number in captivity. Single White-fronts used to be more frequent in the Lee Valley (reflecting their abundance nationally) but were normally ignored or regarded as escapes. These days, they are decidedly scarce. Single Bean Geese in the Valley over the last 30 or so years have all been ‘escapes’, despite at least two being rossicus and turning up in cold winters. Okay, Barnacles are very messy, with the huge numbers of feral birds in East Anglia and the near continent, but most single grey geese are likely to genuine wild birds in my opinion. With a bit of careful consideration, the status of wild geese in our area could be better documented.

Anyway, the goose flocks at Holyfield today included a second Pink-foot that has joined the long-staying bird from last year, and a single White-front was also present. Interestingly, the flock also contains a neck-collared Greylag Goose, caught and ringed in Sweden in 2000 and seen in the UK this winter and last, before apparently migrating back north-east. It was in Bedfordshire, Essex and then Rattray Head in Aberdeenshire last spring, before re-appearing in Cornwall in December.