Sunday, 19 December 2010

What's happened to cold weather?

R-b Merg on the KGV, packed-in Tufties at Nazeing and Smew at Cheshunt.

What’s happened to cold weather? When we had it in the 80’s we were splattered in scarce grebes, divers, gulls and other stuff. This winter has been rather slow, a few Bitterns and Smew (but barely more than usual) and not much more so far. Okay, there were some Eider on the Girling today, and we are knee-deep in Waxwings, but overall it’s not like it used to be.

In early 1979, strong north-easterly winds precipitated a remarkable influx of, amongst other birds, grebes, divers, Smew and Goosander. Within a month my Lee Valley list included 12 Red-necked Grebes, 30+ Red-breasted Mergansers, 2 Slavonian Grebes, 2 Black-throated, 2 Great Northern and a single Red-throated Diver, 26 White-fronted Geese, Hen Harrier, 5 Long-eared and 6 Short-eared Owls.

Likewise, in early 1985, severe weather resulted in a massive influx of Smew (up to 40 at Holyfield Marsh alone), Scaup (9), Slavonian Grebes (5), Red-necked Grebes (4), Velvet Scoter (3), Long-tailed Duck, Bean Goose, Glaucous Gull, Shag and Hen Harrier. However, judging by the length of my notes, a Mediterranean Gull was the most exciting.

Is this current weather not blasting easterly enough, has climate change shifted the distribution of some of these birds, or are there just fewer of them nowadays? Or perhaps a bit of all three?

Cold weather refuges are critical for wintering waterbird populations. These may be provided by the larger, deeper waters of the reservoirs that rarely freeze, or by sites that have flowing water, such as the rivers or the sewage treatment lagoons at Rye Meads. The winter of 2008/09 provided an opportunity to record hard-weather effects in the valley during the short freezing spell in early January. At this time, up to 2,000 birds may have left the valley, with around 1,000 returning as milder conditions prevailed. Dabbling duck were mainly affected with losses of Gadwall, Teal and Shoveler but significant numbers of Coot also left. Birds also re-distributed; Gadwall concentrated on Netherhall GP and the King George V Reservoir, as sites such as Amwell NR, Holyfield Marsh GP and Cheshunt GP froze over.

Thursday, 16 December 2010

Revision of the 30 cm rule.

A Bittern nest at Ham Wall; built in 110cm of water

 It is perhaps surprising to think that until the early 1990s we knew little about the ecological requirements of the Bittern other than it was a ‘reedbed bird’. With the UK population plummeting, research was undertaken at the key sites: Minsmere and Leighton Moss. It soon became clear that it was the drying out of our reedbeds through natural succession that was the main cause. Put simply, Bitterns require wet reedbeds that provide both abundant food and security from predation. The research showed that female Bitterns nested in reedbeds that remained wet all summer and the average water depth on the date of the first egg was 22 cm. The call went out to create new reedbeds, with a recommended spring water depth of around 30 cm.

This week we reviewed the data from extensive reedbed studies over the last couple of years. One revealing analysis was the depth of water that Bitterns in the UK are now nesting in, and the take-home message is that Bitterns appear to be able to nest in as deep a reedbed as a site can provide. At the superb new wet reedbeds at Ham Wall, Lakenheath and Shapwick, recent nests have been constructed in 50cm to 1metre of water. Perhaps we shouldn’t be surprised; a previous Polish study found Bittern nests in up to 97cm of water.

So while the research was invaluable and set out the path for Bittern recovery in the UK, the nest water depths merely reflected the best (wettest) reedbeds at that time. Now we have better reedbeds, the 30cm rule requires revising to reflect our increasing knowledge.  New, big, wet reedbeds are not only going to last longer but will be more robust in the face of climate change and will be attractive to potential new colonists, note the presence of Little Bittern, Purple Heron and Great White Egret this year in our biggest and wettest reedbeds.

Thursday, 9 December 2010

Ouse up and Ouse down?

The Ouse Washes are officially classed as ‘Unfavourable’ condition, due to the increased incidence of summer flooding and the poor water quality. Breeding waders have declined, from an overall total of 900+ pairs in 1990 to around 450 this year. Most notably, Black-tailed Godwits have declined to just 2 or 3 pairs at this former stronghold, and Snipe have also declined sharply.

However, ‘every cloud has a silver lining’ as they say. Under the wetter summer conditions, breeding duck have increased, with average counts over the last five years of 161 pairs of Shoveler, 110 of Gadwall and 9 of Garganey. Spotted Crakes also increase in the wetter years, with up to 4 ‘whippers’ in recent times. These ups and downs mirror the cyclical patterns of species seen in some natural floodplains in Europe – more ducks, grebes and terns in wet years, more waders and Corncrakes in drier years.

The influence of the water regime also applies in the winter, deep floods favour Pochard, Tufted Duck and Coot, shallow floods favour the dabblers; Shoveler, Wigeon, Pintail and Teal.  The highly mobile birds respond rapidly as the water levels change.  There are of course many external influences at work as well. Many wildfowl are ‘short-stopping’ on the continent, due to recent milder (!?) winters. The wild swans, perhaps the washes most notable winter visitors, also show differing trends, but this is not down to water regime. Whilst Whoopers (from Iceland) have steadily increased to over 5,000, Bewick’s have declined to around 3,500. The decline in Bewick’s is concerning as it is clear that poor breeding success is at least part of the cause. The number of juvenile birds accompanying the adults has sharply declined in recent years.

Today the washes were frozen stiff. Whoopers and Bewick’s fed out in the adjacent beet fields, returning in the late afternoon to roost on a small area they keep ice-free. Around 1600 have returned so far this winter. It may be ‘unfavourable’ but the Ouse Washes are still a fantastic place for birds.

Tuesday, 30 November 2010

Owl pellets

Talking of top predators, a while back, a large bag of smelly owl pellets arrived on my desk with the request, “Can you see what’s in these?” They were large pellets, 70 mm long on average and had arrived from, let’s say, an upland location.
Of the 35 pellets collected over two years (12 in 2009, 23 in 2010), 28 (80%) contained mammal remains, including Rabbits (23), Field Vole (7), Brown Rat (1) and Stoat (1). Eleven pellets (31%) contained bird remains (at least 4 Red Grouse and 1 Pheasant, with 2 probable Pheasants). The mass of loose remains found with the pellets included 3+ Rabbits, 1 Field Vole skull, 2 bird skulls (Red Grouse), 1 bird leg (Pheasant) and many Red Grouse feathers (probably from one bird).

So, in this small sample, Rabbits formed the bulk of the prey in both years, with a smaller percentage of Red Grouse/Pheasants, not a surprise as these were all common in the locality. All the voles came from the 2010 pellets, suggesting a local abundance that year.

The diet of Eagle Owls is known to be wide and varied, but usually reflects the local abundance of suitable (available and economic) mammal and bird prey at any particular time. It is also well known to be very intolerant of ‘minor’ predators within its territory, suppressing their numbers through direct predation. Such behaviour is typical of top predators. Although concern has been voiced about their impact on nesting Hen Harriers, we all know what the main predator of the harrier is!  Personally I’m glad this magnificent bird has regained a toehold in this country. Now, what about the Lynx?; that should sort a few things out.

A photo below of an Eagle Owl pellet deposited on the remains of a Bittern! – taken in Belarus I might add.

Friday, 26 November 2010

The grass is always greener

Geese at North Warren – some more dodgy than others – feeding on a fine sward.

A ‘goosey’ couple of days with a Tundra Bean at Vange Wick on Wednesday, followed by a day at North Warren where there were 62 White-fronts, 2 Pink-feet and 3 Fly-over Bean Geese amongst the hordes of birds with, let’s say, a more local origin. North Warren is an excellent winter site, attracting large numbers of wildfowl to the flooded wet grassland habitat. 30+ Pintail lurked amongst the hundreds of Wigeon and Teal, and at least 8 Water Pipits made themselves obvious.

Managing wet grassland may at first sight seem easy – there are only two issues to get right – the water and the sward. However, this does hide a mass of complexities. At North Warren, the brackish influence is allowing the unpalatable Saltmarsh Rush Juncus gerardi to flourish. At the same time, recent milder winters, are allowing more winter grass growth (with an increasingly long growing season predicted under climate change). Together these factors affect the quality of both winter wildfowl grazing and spring breeding wader habitat. The current attempts to halt this shift in sward condition are based around a more dynamic water regime (including holding winter water longer into spring to suppress growth) and the introduction of some winter grazing by ponies. Time will tell if it works. Yesterday, the site looked superb!

Below - Saltmarsh Rush - yuk - no geese (mainly because I'm stood there)

Thursday, 18 November 2010

Stoatally obvious, or is it?

As days shorten and field work becomes less attractive, we tend to find more time for thinking about the big issues in reserve management.  Predation is one such issue.

Reserves that have high numbers of ground-nesting birds often seem to have poor productivity.  Over recent decades, birds and their predators have been increasingly squeezed into smaller areas of good 'honey-pot' habitat.  Predation by Foxes has been shown to account for a high percentage of nest losses in several species eg Lapwing.

So, trying to prevent Fox predation may seem to be the obvious answer on sites where it is proven to be a problem, and this may be attempted by lethal (shooting) or ideally non-lethal measures (such as electric fencing or habitat manipulation).  However, the results do not always seem to be clear-cut. The productivity of the target species may not recover, or other species may unexpectedly decline.

The complicating factor may be 'meso-predator release'. Top predators tend to suppress numbers of smaller, less dominant (meso) predators, such that when the top predator is removed, the meso-predator increases in abundance. So, in Finland, the removal of Lynx can allow Foxes to increase, causing a decline in a key prey species, the Mountain Hare.  In the UK, the removal of Foxes may allow mustellids (generally Stoats and Weasels) to increase, and this may impact on species more vulnerable to mustellid predation. So things begin to get complicated, and answers are not always obvious.

And then there's the inter-action of Badgers with Foxes to consider.....and the effect of fluctuating small mammal populations.   Hmmm, more thinking time required.

Saturday, 13 November 2010

Cheshunt GP, Saturday 13th November, Twenty past Water Rail

I usually find it is about twenty minutes after the first Water Rail has called that they move. I arrive at the best viewpoint as the sun goes down and the Water Rails kick in, at least six noted. A couple of Cetti’s sing weakly from each side of the lake. Still plenty of light in the sky, but start scanning. The ducks become restless, a Woodcock whizzes across the sky onward to some unknown feeding area. The last gulls pass through towards the roost, light levels drop. It’s Mallard time; birds are suddenly flying everywhere. Then the Pochard are alert, nodding to each other, and at some given signal, all get up and fly, probably south to the Thames. Very little light now, keep the resolve, keep scanning. There. The distinctive shape comes across the lake and crashes into the reeds in front of me. The Bittern has returned to its favoured roost site. Time for the football results.

Friday, 12 November 2010

Hands-off Stonies? - not yet.

Shifting Stone Curlews from arable to good quality grassland habitat is essential.

Concerted conservation action has benefited Stone Curlews in recent years, with the result that it has moved from Red to Amber on the BOCC list.  However, Stonies are not ‘out of the woods’ yet.  This week, we reviewed the 2010 breeding season results from two sites; Minsmere and a location in the Brecks.  It is important that the habitat remains in ideal condition. This is assessed by measuring the percentage coverage of three attributes; a sward less than 2 cm in height, the distribution of Rabbits (measured by density of droppings) and the distribution of stones greater than 1cm in dimension. Despite good habitat at both sites, the end of season outcomes were very different. At Minsmere, six pairs raised seven young, well above the 0.7 chicks per pair considered to be the minimum required to sustain the population. At the Brecks site, four pairs failed to rear a single chick over 8 nesting attempts.
So why the difference? Well, at Minsmere, the birds are protected from predation (mainly by Foxes) by electric fencing and a regular wardening presence. At the Brecks site, the birds have no such protection, and predation was suspected to be the main cause of failure. It is this ‘hands-on’ conservation effort that has allowed the Stone Curlew to recover. However, shifting to a less interventionist policy, with an increasing proportion of birds on good quality grassland habitat remains a challenge.

Thursday, 4 November 2010

Blå bård

From top -Dingle reedbed, blue-zone at Minsmere grazed by Koniks, Little Egret.

The tour of reedbeds reached the home straight this week with a visit to Dingle Marshes, part of the Walberswick complex on the Suffolk coast. This is an old, very interesting reedbed, the wetter areas good for Bitterns, the dryer rich in invertebrates and flora. However, looking down from the hill, the first thing that strikes me is the quality of the ‘blue-zone’ around the margins. Blue-zone is the name given to a grazed habitat on the outer edge of the reedbed within the zone of water level fluctuation. As winter water levels recede in the spring, animals follow the water down, grazing the reed and opening up the habitat. As water rises again in the following autumn, a flooded zone is created on the outer margin of the reedbed. Blue-zone management allows a range of wetland plants to flourish, and importantly, can act as a nursery area for fish, or an ideal area for amphibians, and is excellent for invertebrates. At Dingle, we graze with ponies, mainly Koniks, although the picture shows Exmoors. These beasts can create excellent pools through their actions of digging up rhizome to eat during the winter months.
Blue-zone is excellent for birds. Herons, egrets and wildfowl all feed in this habitat. Bitterns have also been shown to feed extensively in such areas. Ranker areas attract Spotted Crakes and it is classic winter habitat for Water Pipits. In spring, waders and duck breed around the shallow pools.
Blue-zone is now a management target on many of our reedbed reserves. Extensively employed in Scandinavia, where it is known as ‘blå bård’ (blue-border), it is considered the most productive area of shallow freshwater wetland for waterbirds. Good examples also exist elsewhere around Europe, with an excellent example at Lake Mikri Prespa in Greece (below - photo Yannis Kazoglou) targeted for Pigmy Cormorant, Dalmation Pelican and Glossy Ibis conservation, and grazed with cattle and water buffalo.

Friday, 29 October 2010

Of crakes and cranes

Fens-bred Crane, view of the washland at Lakenheath (is that a Great White Egret?)

The success of Lakenheath Fen is remarkable. A review of this year’s figures shows two pairs of Cranes rearing one chick, five Bittern nests, 120 pairs of Bearded Tits and 13 pairs of Marsh Harrier (as well as Garganey, Golden Oriole, Spotted Crake, Nightingale and Hobby of course). Just one species, Fen Ragwort, has been re-introduced to the site since it was created (unless you include Reed). But it is not faring well, and this prompted much discussion of the pro’s and con’s of such action.

Re-introductions always seem to be controversial. Take the return of Cranes to Somerset as an example. Now that the small East Anglian population has broken out of its original Broads homeland, and increased its productivity, it is clearly 'on the move'. One key criterion for determining if a species should be re-introduced, or not, is whether it is likely to return 'under its own steam' and Cranes are highly likely to get to Somerset under the current expansion (wandering birds already have). There can be no ecological reason for re-introducing them to the south-west.

On the other hand, it is unlikely that Corncrakes will have returned naturally to the Nene Washes. Although it is great to hear multiple ‘crekking’ crakes at the Washes, the ongoing re-introduction scheme has to resolve many difficulties, not least that Corncrakes are long-distance migrants and are somewhat difficult to observe. Captive-bred Corncrake chicks have been released at the Nene Washes since 2002, with an estimated 21 ‘crekking’ males in 2010. Birds are now breeding in the wild and returning. However, the population is not considered to be self-sustaining as yet due to the low number of returning wild-bred males. The return rate of the ringed, released males is estimated to be around 20%, similar to the return rate estimated for wild Scottish chicks in their first year. Released birds have now been re-captured up to four years after their release – the longest recorded re-capture period for a UK Corncrake. So, adult winter mortality does not seem to be a problem. One potential problem is low breeding success on the Washes, possibly due to habitat issues, and this is currently being investigated.

In deciding whether the ‘driver’ for site management is the habitat or the associated species, few would disagree that overall, the habitat approach is the best. However, understanding the requirements of key species is essential, and ‘tweaking’ where necessary can enhance their fortunes. The example of the recovery of Bitterns in recent years is clear. At the Nene Washes, there are several key species, so which way do you ‘tweak’? Black-tailed Godwits must be a priority, as the site holds the majority of the UK breeding population. However, what might be seen as ideal wet grassland habitat management for the Washes and its waders, may not deliver enough ideal habitat for the Corncrake, which brings us back to a second key criterion for re-introduction schemes – is there enough suitable habitat for the species?

Wednesday, 27 October 2010

Not the River Lee, 18th October.

The usual ‘elf and safety we have become accustomed to was not apparent as, without a lifejacket in sight, we steamed up the mighty River Gambia towards Janjanburay. 'Balance, balance, or we overturn' shouted the Captain, as we all went to starboard to look at a snoozing Hippo. We eventually glided gracefully into the riverbank and leapt off into Kunkilling forest. Within 5 minutes the main target, Adamawa Turtle Dove was posing for photographs. Klass's Cuckoo, Swamp Flycatcher, Violet Turaco, Snowy-crowned Robin-chat, Greater Honeyguide and White-backed Vultures on the nest, all showed well within the next hour or so.
We returned to the rather shambolic Bird Safari Camp, where we were staying for 4 nights during this short, hastily arranged trip to The Gambia. Although the birds were good, notably Verreaux's Eagle Owl, African Scops Owl, Red-shouldered Cuckoo-shrike and Standard-winged Nightjar, the camp has long passed its glory days. Having stayed at the coastal sites in my previous trip 15 years back, I was keen to explore along the length of the river, starting inland and sailing down to the coast. These higher reaches, beyond the tidal influence, were swollen with muddy water and the margins supported good areas of hot and humid forest.
The journey along the river by boat and minibus provided good numbers of the usual species. Egyptian Plovers were the highlight at two wetlands on the north bank. This excellent site held huge numbers of waders and herons, with Senegal Thick-knees, Pratincoles, Squacco Herons and Greenshanks everywhere.

Cruising along the upper reaches of the river provided close views of Black-headed Herons, Striated Heron, Osprey, African Fish Eagles, Martial Eagle, Red-necked Falcons, Hammerkop, Hadada Ibis, Spur-winged Goose, White-faced Whistling-duck, Broad-billed Rollers and Woodland Kingfisher. Chimpanzees, Baboons, Red Colobus and Green Vervet Monkeys appeared at intervals along the banks.

It's always good to have the lady along to help find birds.
"I've got a large orange and blue bird at the back of the wetland" she said.
"okay, whereabouts?" said I.
"oh it's washing".
"okay, but whereabouts is it?"
"it's washing"
"Yes, I heard you, but where is it?"
"No, it's washing, on a line."

The middle reaches; Tendaba, 23rd October

We landed at Tendaba quay to be met by a multitude of tiny kids all keen to grab hold of, and carry, something. A mass of little hands carried scopes, rucksacks and bags into the camp in exchange for a few Delasis. We dined on roast Warthog and retired to the sweatiest night I can remember. The alarm, half hour before dawn, was a long time coming. The early morning boat trip cruised through the mangrove swamps and creeks. Here, the main river is saline and tidal. Blue-breasted Kingfishers, Mouse-brown Sunbirds and Oriole Warblers mixed with the more familiar Whimbrels, Avocets, Little and Caspian Terns. Anhingas, Great White Egrets, Woolly-necked Storks and Goliath Herons peered down from adjacent trees and West African Crocodiles and Monitor Lizards loafed on the banks. A White-backed Night Heron on its nest almost gets knocked out of the way as the boat passes.

The coast; return to Kotu Creek, 25th October.

I was keen to see how the Kotu area I had roamed around 15 years previously had changed. Standing on the banks of the Kotu 'pools' (aka the sewage works) watching sandpipers, shanks and stilts feeding around the disgorging tankers brought back memories of Wisbech in its heyday, or even the string of small sewage works along the Lee Valley.
Surprisingly, Kotu Creek appeared to have changed little apart from increasing growth of mangrove and some small areas now inaccessible. The Giant Kingfishers were almost in the same tree and the mudflats were full of waders and herons. White-faced Scops Owl, Bearded Barbets, Lizard Buzzards, Fanti Saw-wings, African Thrush and Blue-bellied Rollers were amongst the many species performing well.
Royal, Lesser Crested and Sandwich Terns fished just offshore, Grey-headed Gulls and a single Kelp Gull flew south.
Although only a brief visit, the area still seems very 'birdy', with the key areas intact despite the obvious increase on development over the years. Meanwhile, our airline had gone bust! Oh well, an extra day on the beach, Ladyfish for dinner, and plenty of Julbrew.

Thursday, 14 October 2010

Right place. Right time.

Sub-dividing the east scrape at Minsmere should allow for better water control and help to alleviate the early drying of recent summers.  Lower: a ridiculously tame Red-flanked Bluetail photographed with my mobile phone.

Just occasionally work is in the right place at the right time. This week was one of those times. A review of the scrapes at Minsmere has identified some changes to improve the hydrology. I stopped off to look at how work was progressing, with the added bonus of the King Eider bobbing up and down off-shore. Then, on to the Hickling area to take a look at Bittern and Crane nesting locations. Nearby, a highly successful reedbed restoration project was undertaken by the Norfolk Wildlife Trust nearly ten years ago. Commercial reed-cutting is often considered incompatible with conservation objectives by site managers. However, I have never gone along with this view and Hickling shows how this can be achieved through a careful mix of commercial (short rotation) and conservation (longer rotation) reed-cutting. The key issue for Bitterns is the need to reduce water levels for reed-cutting in the early part of the year (Jan-Mar) at just the time when they require higher water levels to provide good feeding conditions to bring them through the winter and into breeding condition. However, cut compartments are favoured by nesting Cranes and a mosaic of cut and uncut blocks are ideal for Bearded Tits.

Stunning views of two birds at nearby Waxham rounded off an enjoyable couple of days – a Pallas’s Warbler hovering 3 metres in front of me and a Red-flanked Bluetail feeding around my feet.

Sunday, 10 October 2010

A push and some Shovs

At last, a reasonable day in the valley. With low cloud over Holyfield hill from first light, birds were passing close overhead and heading mainly west or south-west. The highlight was a single Lapland Bunting, flying low and fast from the east at 8.45, calling overhead, and again as it sped west across the valley. Small flocks of Redwings appeared every few minutes, with 342 counted in total.  A hedgerow to the rear of the hill was alive with thrushes, a Ring Ouzel lurked with Redwings, Blackbirds and Song Thrushes, and a further two Ouzels dropped out of the gloom into a scrubby area further back. A Marsh Harrier, picked up over Nazeing, headed south down the valley over Waltham Cross. Other totals included 271 Starlings, 32 Skylark, 43 Mipits, 23 Song Thrush, 22 Blackbirds, 57 Chaffinch, 3 Brambling, 3 Reed Buntings, 17 Goldfinch, 1 Yellow Wagtail and 4 Swallows. The clouds rose and the sun appeared around 10.30.

With most of the vis-mig action over, I looked around a few sites in the northern section of the valley specifically for Shoveler and amassed a reasonable total of 172. Most of these were at Rye Meads: a total of 105, with a single Garganey still present.  The Lee Valley supports internationally important numbers of Shoveler. However, although one of a number of winter visiting wildfowl that seem to be declining in the valley, the Shoveler is the exception in that ‘short-stopping’ is not a likely reason. In fact, UK wintering numbers appear to be increasing as fewer UK birds move south for the winter.

Shoveler numbers in the Lee Valley have dropped by around 10% over the last 10 years. There has been concern over sharply declining numbers on the King George and Girling reservoirs. However a closer look at the data shows peak numbers on these sites were mostly in years when water levels were low for some reason, and this is the crux of the issue. Shoveler tend to prefer shallow, productive wetlands and much of the valley is heading in the opposite direction. Only a very few sites in the valley can manage water levels for the benefit of nature conservation. Perhaps more should be done for the Shoveler – we might even get a few waders as well!

Tuesday, 5 October 2010

Where is the passion?

"Get out of that hide boy!" was the first thing Bert Axell said to me, as I snuck into Minsmere on a non-open day to see the Terek Sandpiper . Perhaps not noted for his visitor skills, Mr Axell's passion for his work was to be admired and the word 'scrape' entered the birding vocabulary. Many other ‘old school’ wardens were equally well known and respected; they knew their birds. Some were not interested in rarities but delivering for birds drove them. Having got into conservation and thinking about 'new' ways of managing wetlands, I usually found that Norman Sills had already researched it years before. Credit where credit’s due.

How times change. Am I a grumpy old git or is it 'just a job' to an increasing proportion of reserve wardens these days? When stocking leaflet dispensers comes before insightful fieldwork or paperwork becomes priority over rushing out for a reserve 'first', I begin to worry. Where is the passion? Basic management skills (like managing water levels) are being lost, not being transferred. How can you deliver the potential when you don’t walk the ground? However, where do we point the finger? At the wardens themselves, or at those that appoint them?

Friday, 1 October 2010

St Aidan's down to Rainham

By any reckoning, St Aidan's is a large hole in the ground. Formerly one of the UK’s largest open cast coal mines (operated by UK Coal), this site, located alongside the River Aire to the east of Leeds, has now been re-landscaped to form a huge wetland complex of open water, wet grassland and reedbed; assessing the development of the latter was the aim of this latest stop on the reedbed tour.
We looked around this impressive restoration with the Swillington Ings Bird Group, who have been doing a good job monitoring the site. The new 50 hectare reedbed is on the cusp of doing great things; Bitterns and Marsh Harriers are eying up the site and will undoubtedly colonise within a couple of years. Electro-fishing revealed a fish community still in an early successional state – good numbers of Perch patchily distributed but little else other than Sticklebacks and a few Pike. However, the developing aquatic flora of Water-milfoils and Water-crowfoots on this poor subsoil substrate looked excellent. These early successional conditions are typically ideal for Dabchicks, with 56 broods reported this year. Four Marsh Harriers and a Red Kite circled over, a Bittern emerged from the ‘fishiest’ ditch, and waders were represented by Curlew, Golden Plover, Lapwing and Dunlin.

The final day of the week was spent in the wind and rain walking the ditch-lines of Rainham Marshes in order to come to a better understanding of how water flows around the site. The fixed facilities of a visitor-orientated nature reserve often conflict with the flexibility required to manage a site to its ecological potential. With new viewing facilities being constructed, the complex hydrology is in need of an overhaul. The aim is to work towards a more strategic and better use of the available water resources, and overall, provide better birding. Curlew, Rock Pipit and Med Gull appeared out of the driving rain.

Saturday, 18 September 2010

Purple patch

Good Bitterny reedbeds, GWE and a Medicinal Leech.

And so to Dungeness, where, thigh-deep in water, counting reeds, a party of 17 Glossy Ibis passed overhead unnoticed. Reedbed creation work in the mid 2000’s is beginning to bear fruit. The improved conditions in the reedbeds has triggered the first proven breeding of Bitterns, and as a bonus, the well publicised pair of Purple Herons. PH’s have similar nesting requirements to Bitterns and although this year’s breeding will be seen as opportunistic, credit is due to the site staff for creating ideal conditions within the reedbeds. A day was spent recording the habitat characteristics around the nesting areas.  The PH nest was a sturdy platform created from bent stems of reed woven together with additional reed and stems of Great Water Dock.
It’s always good to remove the waders at the end of the day and wiggle the toes in the cool water – at Dunge you get the added bonus of watching the Medicinal Leech’s loop towards you. Little Gulls, Black Terns and Great White Egret couldn’t make up for the disappointment of missing the Ibis.

Thursday, 16 September 2010

Kick-ass Perturbation

Radipole Lake, Little Egret.

Too many of our wetland nature reserves have become ‘tired-looking’ and ‘stale’ over the years. Ongoing same-old, same-old management has allowed stability in the habitats, usually with competitive species becoming dominant. In many habitats, a degree of disturbance can knock back the natural succession and open up opportunities for a greater variety of species to flourish again. This management disturbance may mimic natural ‘catastrophes’ such as wind, flood, ice or fire, which, in the longer term, are rarely as bad as they first seem. Such ‘Kick-ass Perturbation’ (as a colleague nicely puts it) can be highly beneficial as the habitat vigorously recovers. A good example is the recovery of the Strumpshaw fish population here.

Why don’t we do more of this KP? Well, lack of resources, perhaps a fear of change, and of complaints from visitors (incl. birders) who see the changes as damaging, are some of the reasons. The first time I instructed a large excavator to re-dig an old ditch on a SSSI, I couldn’t sleep for days I was so worried about what I had done. Within minutes the black scar was extending across the land and the ground shook as each bucketful of silt was lifted. One year later the site looked fantastic, ‘long-lost’ species had returned.

Anyway, getting to the point, and on to Radipole Lake, the latest stop on the reedbed tour. On a previous assessment back in 2006, I had identified the lack of lack of structure within the reedbeds and the lack of ditch maintenance as a key factor in the site’s decline. A plan was drawn up. That plan is now halfway through implementation and the initial results look excellent. Some great looking KP has been performed on the ditches and pools. The water now ‘boils’ with invertebrates and fish, and studies of the bats has shown increased use of these restored areas by feeding Daubenton’s and Noctules. Give it 2 years and I will expect booming Bitterns.
The major distraction during the visit was the number of Great Green Bush-crickets chirping away. Lodmoor looked good, with 3 Curlew Sandpiper, 2 Spot Reds, Ruff, Redstart, Wheatear and several Med Gulls.

Below - aerial views of Radipole before and after restoration of the ditch systems.

Saturday, 11 September 2010

Patch-birders everywhere grateful to ‘little and large’ (as long as they didn’t see their legs).

Little and large at large in Bedfordshire (Steve Blain).

One particular pair of Cranes, ‘little and large’, have done much to make patch birders happy this year, from North Norfolk down to Sussex, across to the midlands, and back to Fakenham. However, a close view reveals an inconspicuous ring on one bird, revealing a captive origin.

Most would agree that Cranes are spectacular birds, well worth having roaming around the countryside. With a combination of human tinkering (a small handful of these birds have a captive origin) and a westward expanding European population, Cranes now seem to be finally getting a grip in the UK with around 15 breeding pairs this year, rearing 6 youngsters. Now splitting into several sub-groups in the UK, the total number of birds is close to 60.

Despite their size, Cranes can be remarkably elusive when nesting. They appear somewhat unfussy in choice of nesting location given a few basic parameters – the nest is usually in shallow water and some peace and quiet is near the top of their list (ie a large wetland habitat). But perhaps it is the quality of the chick-rearing habitat that is more important. Predation by Foxes has proved to be a key constraint in the UK. For the first few weeks of life, the chicks forage close to the nest. However, as they then start to roam wider, they become more vulnerable and many chicks succumb before they reach the end of the 10 week fledging period.

Monday, 6 September 2010

Roll over Rainham

This may look like a building site to you but to me this is a wide creek around 1m deep, stretching away from the sea wall, and then sub-dividing into narrower ditches and foot-drains (lower picture). Winter rainfall will fill and flood the site, draining down in summer to reveal muddy pools and edges. Specially designed scrapes will pull birds towards the viewing positions. This is the start of the next mega wetland site in Essex. This site will be special! Work started this week on Bowers Marsh to create a complex of wet grassland, scrapes and saline lagoons. Roll over Rainham.

Across the way, Vange Marsh scrape continues to pull in the birds. A shot below from last weekend shows Spoonbill, Red-necked Phalarope and Saltmarsh Goosefoot (don't believe everything you read in British Wildlife) - got them all? A quick sift through the mud and water today revealed one reason for the site’s success – food. Abundant chironomid larvae in the mud (bottom picture) and corixids (Lesser Water Boatman) in the slightly brackish water. Even West Canvey is getting in the act with a Temminck's Stint.

Thursday, 2 September 2010

Starlet steals the show

View across Havergate (with 14 Spoonbill), Avocets arriving at high tide, Starlet Sea Anemone - a rare specialist of coastal lagoons.

Equipped with sifting trays, nets and a supply of red wine, I had Havergate Island to myself for two days. The aim was to undertake a survey of the saline lagoon fauna but with a light easterly blowing, I was hoping for more.

Famous as 'Avocet island', recent years have seen a dramatic change in bird populations on the island. From zero a few years back, the island now supports 1200 pairs of LBBG and 600 pairs of Herring Gull. The increase in gulls has resulted in a corresponding decrease in breeding Avocets, Ringed Plovers and terns, due to predation. The gulls have moved to Havergate from Orfordness, where they have been decimated by Fox predation. However recent years have also seen an increase in Spoonbills, with counts here or at the adjacent Orfordness being the UKs highest, 14 were still present during the visit.

The lagoons at Havergate are also important for their specialist invertebrates. The sampling revealed a high biomass within most lagoons; ragworms, the amphipod Corophium, Lagoon Cockles and abundant Palaemonetes shrimps, but perhaps the most important saline lagoon specialist is the Starlet Sea Anemone. However, with a body only 2-3mm long, this is not the most obvious beast.

Avocets still favour Havergate for feeding, 620 were present, along with 250+ Redshank and 50+ Black-tailed Godwits. Other bird highlights included 50 Common, 26 Sandwich, 1 Arctic and 1 Black Tern, Peregrine, Hobby, 3 Pintail, 15 Greenshank, 2 Spotshank, 10 Knot, 60 Golden Plover and 28 Bar-tailed Godwit. Passerine migrants were represented by a Reed Warbler, a few Wheatears and a Rock Pipit. Could have been better, but the sunset was worth it.