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.
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