Friday, 29 October 2010
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
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?"
"Yes, I heard you, but where is it?"
"No, it's washing, on a line."
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.
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
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
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!
Friday, 1 October 2010
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.
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.