Friday, 22 February 2013

January at NWT Upton Broad and Marshes

Nigel Robson, Volunteer Bird Recorder for NWT

These accounts of birds at Upton Broad and Marshes are based only on my observations unless otherwise mentioned, usually from between two and four visits a week, at different times of day and covering parts of the reserve (predominantly the grazing marshes). At best I hope from this to provide a snapshot of which species occur when and where, and how they are responding to changes to the habitats (planned and unplanned), climate variations, agricultural influences and any others factors.

During the first half of January, the reserve had generally low numbers of the typical birds wintering in Broadland, despite the grazing marshes remaining suitably saturated and holding many flashes of open water. Lapwings, golden plovers, winter thrushes and starlings were sporadic, and no more than a handful of duck and Bewick’s swans visited. On the other hand, cranes were regularly drawn from their winter stronghold immediately across the river at St Benet’s Level to the recently-created scrapes in the west of the reserve. During this period, St Benet’s Level provided for good numbers of lapwing, golden plover and Bewick’s swans (115 and 8 whooper swans on 6 January). The mixture of arable (maize cropping) and grazing marsh there is clearly favourable to these birds, and also to winter flocks of linnets and skylarks not found in such numbers in the reserve. This example of the interdependence of wildlife on the wider landscape illustrates the need to work with surrounding landowners, as embodied in NWT’s Living Landscape Initiative in the Bure Valley.

Green Sandpiper, photo by Julian Thomas
The daily movement of cormorants flying over the reserve in late afternoon to their roost at NWT Ranworth Broad provided an impressive spectacle, with formations totalling up to 1,000 birds. Other winter visitors seen throughout January included a green sandpiper, two redshanks and a peregrine. The reserve staff had a single sighting of a hen harrier. A small number of meadow pipits frequented the soke dykes, and inhabitants of the reed swamp beside the river were a few scattered reed buntings, an unobtrusive group of bearded tits, the odd Cetti’s warbler, and of course the ever-present wren which calls from all corners of the reserve.

Away from the marshes in the undrained fen, a work party on the Doles was completing the planned clearance of sections of scrub and alder carr to reclaim herbaceous fen. This nationally-rare habitat contains some of the floristic diversity for which the reserve was designated SSSI. It is the stronghold of the grasshopper warbler and water tail, but otherwise its avian diversity is limited. There will be winners and losers as a consequence of these changes. The elimination of a large area of mixed scrub around Little Broad will reduce the number of breeding willow warblers and the potential for a breeding long-eared owl, both species being strongly reliant on those conditions in the Broads.

The species composition and numbers of waterfowl using Great Broad in winter vary, and daytime counts during the months before and up to mid-January were low. The WeBS count on 13 January is indicative of this, amounting to 55 birds of 7 species. But with the snow and freezing conditions that followed, activity increased. On 17 January the Broad was 90% frozen, and the count was 120 birds of 7 species. Mallard was, unusually, the most numerous at 65, and duck included a drake pintail. Six days later, the Broad was 85% frozen and the count 244 birds of 8 species with teal most numerous at 169. In the surrounding woodland, woodcock were relatively plentiful.

Common Teal, photo by Chris Mills
Snow blanketed the grazing marshes for many days in the second half of the month, whilst the river lagoons, subject to tidal influence, stayed partially unfrozen. Like the broads, they became the focus of activity, attracting up to 200 teal, accompanied by small numbers of mallard, gadwall, shoveler, tufted duck , pochard and a shelduck. A pair of pintail also settled in for a stay, the drake probably being the same bird seen on Great Broad. A scattering of snipe occupied the edges. Wigeon were frequent over-flyers from the adjacent Oby marshes but they are as yet reluctant to land on the reserve’s lagoons and marshes, possibly being outside their “comfort zone”.

With grey skies and cold winds persisting, the pattern remained set to the end of the month.

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