Thursday, 28 March 2013

Come schnell and high water

'Er indoors said she enjoyed last year’s trip down to Seville and Donana; must be the Lynx effect.  So a return trip was in order. Aha, a chance to check out Baillon's Crake habitat and gauge possibilities of northward movement this year.

Arriving at El Rocio on the western edge of the Donana National Park, it was clear that this was no drought year: it was wet, very wet.  Water levels were very high.  A heavy storm forced us into the local restaurant to debate the finer qualities of Coquinas verses Almejas, accompanied by some fried anchovies, and a little octopus of course.  With full bellies and the rain easing, we ventured out to look over the lagoon.  At the tail end of the storm, Sand Martins and Swallows were moving in numbers. An estimated 10,000 passed through over the next hour, the naked eye view appearing as a mass of midges swarming over the water and all moving northwards with purpose.  Slowly the sun broke through and temperatures rose.  The soft rolling ‘prruup’ noises from above broke into the consciousness as dozens of Bee-eaters streamed through.  Now concentrating upwards, Black Kites, Booted Eagles and Red-rumped Swallows dotted the sky in a steady movement. The odd Monty’s and Purple Heron added interest.  Warm sun on the bones and birds on the move; what could be better?

Early next morning we were out looking around the marshes; they were wet.  Spotted Crakes, Baillon’s Crake and Water Rails crept around the flooded swamps.  Not much chance of a major northward push of Baillon’s this year.  In last year’s drought conditions, Baillon’s, Stilts and Glossy Ibis all moved northwards searching for better conditions.  It also delayed the onward passage of Spoonbills due to poor feeding.  No such problems this year.  Feeding groups of Spoonbills, several colour-ringed, were swishing energetically, belly-deep in water and frequently flicking up and gulping down small fish.

There were many birders around and most seemed to be Germans. A beckoning "Come, schnell" provided me with close views of Purple Gallinule.  Savi’s reeled from every swampy hollow, Subalpine Warblers disappeared around every patch of scrub and Woodchats dotted the tops of bushes.  Nightingales sang and Redstarts flitted.  As lunch time approached, the baby lamb chops needed some consideration (oh the flavour!) and after several glasses of rioja, we were surprised to see a Lynx run right through the restaurant.

Below - Lynx in pine wood

Wednesday, 20 March 2013

Oil platform

A day out this week on the Essex coast at Wallasea with colleagues from Buglife looking for Oil Beetles.  As luck would have it, we hit a warm sunny morning,  with singing Corn Buntings everywhere.  And plenty of the target species; Black Oil Beetles Meloe proscarabaeus, along the seawall, mostly doing what Oil Beetles need to do in the spring..  The name derives from their habit of releasing oily droplets from their joints when disturbed; this contains cantharidin, a chemical apparently causing blistering of the skin and painful swelling.

The life cycle is fascinating.  The female beetle lays up to 1,000 eggs in burrows close to the burrows of mining bees. The larvae, known as triungulins, climb up into flowers and wait for a passing bee collecting pollen.  They then hitch a lift on the bee back to the bee’s nest where they munch their way through the bee’s eggs and pollen supplies.  The adult beetles emerge from the bee burrows after overwintering.  More on the Buglife website here.

Sunday, 17 March 2013

Comings and goings

Despite the reluctance of winter to give way to spring, comings and goings have been evident in the last few days.  Today at Hall Marsh, where some excellent management has been undertaken by the Lee Valley Park, a Little Ringed Plover was back on territory, a Sand Martin headed north and a Chiffchaff sang from nearby bushes.

A few days earlier I had waited in vain at Amwell for a Great White Egret to return to the roost, but luckily witnessed a far more interesting event.  At dusk a Bittern drifted headed across the lake and dropped into its usual reedbed roost site. Nothing unusual there.   However, 15 minutes later, in the gathering gloom it rose out of the reedbed to begin circling up into the sky giving the little known ‘gull call’.  Within a minute or two a second bird had risen out of the reeds to join it, both dark shapes now just visible circling over the lake.  As they rose and drifted northwards, a third calling bird appeared from the south to circle the lake.  This bird disappeared high into the gloom back southwards with its far carrying call audible long after the gloom had swallowed up it’s shape. 
The ‘gull call’ can be given by both male and female Bitterns and has mainly been associated with pre-migration behaviour when birds circle up into the sky at dusk.  This behaviour is well known on the continent, where groups of up to 20 birds are noted at key wintering or passage sites.  However, the ‘gull call’ may also be heard in aerial chases over breeding sites in early spring. 

Although many of our wintering Bitterns are assumed to come from the continent, there is little firm evidence of this.  However, satellite tagging birds in the Netherlands has produced some interesting results.  Check out Anneke on this page.    Anneke was ringed in the Netherlands in 2011.  In October she arrived in the UK over Hull, toured Wales and then settled at Slapton Ley in Devon from late November to the end of February. On February 26, she flew back to the Netherlands with a stopover in East London after a flight of 900 m above the city.  Then she returned to her natal site, crossing the North Sea at over 60 miles per hour.

So our Lee Valley birds may be heading back to distant breeding areas but there is plenty of Bittern breeding activity in the UK already this spring, with a remarkable 35 booming birds in Somerset, good numbers in the north of England and some new sites occupied. With Great White Egrets also getting jiggy on at least two sites, this spring will be interesting.

Friday, 15 March 2013

Goshawk snippets

Last week developed a Goshawk theme.  A day in the Brecks on one of the few warm spring-like days so far resulted in some opportunistic top-of-forest watching, with views of a displaying pair in a regular location. Largely a bird of big forests, Goshawk has a small but increasing population in Thetford Forest with eight pairs located by regular observers last year.  I then departed for a couple of days in deepest Wales, where despite deteriorating weather, I was lucky enough to see another couple of birds.  The first was a male flushed from a woodland ride early in the morning.  It weaved its way heavily between the trees carrying a lumpy prey item which appeared to be a crow.  Landing in a small copse ahead of us to pluck the bird, we crept forward hopeful of a reasonable view, but typically it vanished in a couple of wing-beats, taking its breakfast with it.  Later, it or another male was displaying over the woodland, pinpointing a possible nest site.  Two UK studies have shown that crows and pigeons make up the bulk (around 68%) of the diet of Goshawks during the breeding season.  This is similar to the diet of Dutch birds but different to those in Scandinavia where grouse make up a bigger percentage of the prey.  The Goshawk has little competition in the UK.  Peregrines are closest in diet but Goshawks are more versatile; taking prey in wooded landscapes and from the ground.

Locally in the Lee Valley area, I have only managed a paltry three birds in 40 years of birding, and one of those had jesses.  Even four years of living in a house overlooking Epping Forest, where they are regularly claimed, resulted in nil sightings. The aforementioned bird with jesses; at Amwell in 1988, memorably took a Wood Pigeon with some force in flight, turning the pigeon into a firework explosion of feathers in the sky, followed by the gently descending feathery sparkles after the birds had long gone.