Friday, 28 December 2012

Don't tell him Pike

I saw my first Bittern in Nightingale Wood in 1972.  The London Bird Report has it as:  Cheshunt GP, one on Mar 4th (GJW).  Hmm, rather brief for what I seem to remember was a good find at the time.   However, over the years this has become a regular haunt for wintering bitterns.  So why do Bitterns return to this spot year after year?

Nightingale Wood is a wonderfully scruffy few acres of wet self–set woodland on the edge of a badly restored gravel pit.  It’s landform is varied to say the least: hollows, holes, slopes, cliffs, pools and piles of reject gravels.  Initially colonised by Hawthorn and willow scrub but now succeeding to Ash and Alder, with masses of dead wood. The modern mineral planning officer would never allow it.  They would smooth everything out, cover in top soil and insist on regimented rows of planted trees, and in doing so would eliminate any decent habitat.

Nightingale Wood? I hear you say.  Well yes, once upon a time in the scrubby days, 2 or 3 pairs were to be found.  I found my first Nightingale nest in this wood and watched the youngsters fledge.  Many a Willow Tit nest was also noted.  Over the years the wood has provided regular Woodcock, Water Rails, Siskins and Redpolls , but also 3 Golden Orioles, 2 Firecrests, 2 Wood Warblers, Pied Flycatcher, Great Grey Shrike, Bearded Tits and a roost of 9,000 Fieldfares one night.  The edge of the wood grades into the water-filled pit through tumble-down wet woodland and marshy spits to a reedbed fringe of about an acre.

This is where the Bitterns come in. So why do Bitterns return to this spot? The varied topography of the wood continues out under the water with deeper pools interspersed with reedy shallows.  Research papers will tell you that Rudd and Eels are the preferred prey of breeding birds in the UK, but Perch and Pike aplenty tuck into these watery hollows in the reedbed during the winter and form the main prey for Lee Valley Bitterns in the lean months. Good feeding at this time of year is crucial for getting the birds through the winter and into good condition for breeding.

I returned to Nightingale Wood yesterday for an hour or so at dusk and a couple of Bitterns were on show.  There are currently 7 or 8 Bitterns wintering in the Lee Valley, with 5 in the Cheshunt pits complex.  The reedbed now has excellent viewing rides cut into it by the Lee Valley Park Authority.  One Bittern duly appeared on the edge of a reedy ride no more than a dozen paces from my original sighting in ‘72.   It caught a nice stripey Jack Pike and soon dispatched it.  At dusk both birds moved with just a brief few wing-beats from the feeding spots to the safe roosting areas on the edge of the reedbed.   That’s why they come back here.

Monday, 24 December 2012


One frosty morning last week, I was out in the Fens again looking at Cranes.  The nesting pair were back on territory, after some weeks of touring the Fens.  Last year’s youngster was still in tow but will surely be given the boot as spring approaches. Cranes have had their most successful year in the UK since returning as a breeding bird, with up to 24 pairs rearing at least 13 youngsters.  The Fens offshoot of the Broads population now seems well established

The winter food of these birds is a mix of agricultural remains and more natural foods from wet grasslands.  The Cranes had been feeding extensively on beet tops earlier in the winter.  One family party were feeding in a maize strip, picking cobs off the standing crop.  Spuds seem to be a good food also.  Spuds left in the ground after harvest may be favoured as they are fresher, but good farming practice usually leaves few available for the birds.  Piles of dumped spuds have been used to attract birds but it appears Cranes prefer them fresh, so replenishing stocks may be the best approach.  The birds I was watching were feeding on waste grain put out for them.
Winter roost sites are important, with birds favouring shallow flooded areas. Ideally they will be close to feeding areas but birds will frequently fly some distance to a suitable roost.

So if we want to attract Cranes, or keep them in a particular area for viewing, why not grow small areas of sacrificial crops - spuds or maize, adjacent to wet grassland etc.   Also, ensure that suitable winter roost sites are present.   Shallow flooding of some cropped land would be beneficial.    These techniques are well known to attract cranes and geese in the USA and such management would also benefit other farmland birds.  

Monday, 17 December 2012

In the beginning.......there were LRP's

 As December ticks away, I eventually get to the task of sorting out the years records from the notebook.  If only I was a little more organised.  This week’s task was to complete the analysis of one of my regular breeding bird surveys; at Amwell Quarry (now nature reserve).  The run of data on breeding birds for this site now extends back to the late 1970s when mineral extraction began.  Why have I done this for 35 years?  Who knows, it just happened.

Eighty species have bred at Amwell over those years, 46 of them managing to enter the ‘scoresheet’ for 2012.  This is somewhat below the 53 species in the best year; 2001.  These 46 species amounted to a total of 327 pairs of birds, again somewhat below the peak of 410 pairs in 2002.  So the headline story is somewhat of a rise and fall.  However, as you would expect, these figures hide the many changes over the years.  A number of species, such as Willow Warbler, Yellow Wagtail (5 pairs in 1983), Turtle Dove, Linnet and Tree Sparrow, have all declined more or less in line with national trends.  But without doubt, the major influence has been successional changes in the habitats, with meadow, marsh and mud being replaced by reed and willows. 

These changes have, of course, produced a number of winners: Grey Herons and Cormorants in the trees, recently joined by Little Egrets, and Reed Warblers, Cetti’s Warblers and Blackcaps in the reed and scrub.  In addition, Black-headed Gulls and Common Terns have used the rafts provided.  The losers have been the grassland birds of the old meadows and more significantly the variety of wildfowl and waders.  Tufted Ducks peaked at a massive 62 broods in 1987 but have since dropped away to low single figures.  Likewise, Gadwall rose to a peak of 12 broods before dropping to just one and after peaking at 53 pairs, Sedge Warblers have dwindled to just 14 as habitats have changed.

Wading birds, particularly the Little Ringed Plover, have always been a key feature of the site since the mineral extraction began.  LRPs peaked at 8 pairs but with numbers rising and falling in relation to the amount of habitat.  Despite the recent addition of Oystercatcher in recent years, LRPs and waders in general, are now teetering on the edge of disappearing as breeding birds.   The problem is that the relentless march of reed and other vegetation across the formerly open areas outpaces the management effort.  What is needed, what most old gravel pits need, is a bit of Localised Intermittent Catastrophe.  A combination of controlled vandalism with a large digger and some dynamic water management should help knock selected areas back to an earlier stage in the succession so the process can start again.  We gathered on site this autumn, umm-ed and arr-ed a bit, and some good work was subsequently undertaken, but on reflection, much more of the same will be required if LRPs are to remain until the end.

Below - Amwell 1987 (8 prs of LRP), Amwell 2012 (none).