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.