Gas gun starts spring sprint

 

After a long cold late winter, spring finally arrived in a wave of migrants, with interesting reports of breeding birds now arriving thick and fast.  Spring also usually means a flurry of site visits for the Grumpy Ecologist and this year has been no different; from East Anglia to the Insh Marshes and across to Wales.   The Nene Washes are always a highlight in the spring.  Reports of a gas gun keeping Cambridgeshire residents awake at night were tracked down to an over enthusiastic booming Bittern in a fenland drain.  The breeding success of waders on the washes has been poor for the past three years, due variously to drought or flood.  Fingers are crossed for a good breeding season this year.  The cold and wet winter has left many wet grasslands in good condition; short swards with a lack of winter growth and brimming pools and ditches.

The trip to the Nene provided evidence of the seasonal changeover.  While 800 islandica Black-tailed Godwits huddled together around the pools, 30+ pairs of limosa noisily ‘wickered’ and chased around the fields.  Snipe chipped and drummed over a feeding flock of Dunlin, Ruff and Ringed Plover. Garganey zipped past the last few Whooper Swans.

Over at Ynys-hir, an early morning visit coincided with an arrival of Wood Warblers, trilling through the woodlands.  Pied Flycatchers and Redstarts were already in good numbers. All three species, typical of these West Atlantic Oakwoods, were seen well from the Ynys-hir canopy hide but the highlight was a Goshawk gliding and twisting through the still bare trees with its entourage of squawking crows marking its passage.  Wood Warblers have declined by 60% in a little over a decade (BBS data), and over a longer period have disappeared from many eastern and southern haunts, yet the reason for this decline is still unclear.  Potential causes include changes in woodland structure, increased predation and a phenological mis-match between egg hatch and the peak of caterpillar emergence. Studies in Wales have failed to point the finger at any of these and indeed have shown that the timing of Wood Warbler breeding can track the annual variation in caterpillar emergence.  Perhaps the answer lies in Africa.

Every cloud....

Black-tailed Godwit and Snipe

On balance, this spring is not shaping up to be a great one for the 50 or so pairs of breeding Black-tailed Godwits in the UK, with their primary locations on the Nene and Ouse Washes both flooded out by the heavy April rains...but every cloud has a silver lining so they say.   I visited the Nene this week; floodwaters are receding and although both Godwits and Snipe were busy displaying overhead, surely time is running out for the Godwits to produce many young this year.  There is an increasing urgency to attract them to new sites, either existing or created, that do not function as storage washlands for summer downpours.   So what do they require?

Godwits favour large, open wet grasslands and marshland.  A Dutch meadow-bird conference I attended some years back explained their dislike of ‘up-going structures’ as the Dutch liked to call them, and this included trees, hedges, buildings and the like.   They like to see in all directions.   After arrival on the breeding grounds, adult godwits require grasslands rich in soil invertebrates, probing for earthworms where high water tables push them close to the surface. They also seek out shallow pools as safe roosting sites.  The chicks have different requirements.  They seem to require longish (20cm) grass, often flower-rich but always with an abundance of invertebrates, particularly flies and beetles, amongst the vegetation. The density of the vegetation is important, with sparser swards preferred for the chicks to forage amongst.

A particular problem appears to be their attachment to natal locations and their slow colonisation of new sites.  So both the RSPB and WWT have been busy creating new habitat on ex-arable farmland adjacent to, but outside, the Ouse Washes to try and attract breeding Godwits.   After some years of ‘maturing’ habitat, an excited text from the site manager over the weekend brought the news that the first Black-tailed Godwit chicks had hatched on the new RSPB land.  Somewhat ironically, the heavy rain and resultant flood has pushed the few remaining Ouse Washes Godwits onto both the RSPB and WWT new habitat. Let’s hope they stay there.