NWT Upton Broad & Marshes: Birdlife, January to March 2014

Nigel Robson, Volunteer Bird Recorder for NWT and Mark Crossfield, NWT assistant warden for Bure and Ant

Oystercatcher, photo by Mark Crossfield

As the New Year arrived, waterfowl on the nature reserve’s wet grazing marshes during December remained at the unprecedented level of abundance. There were some 3,500 pink-footed geese in the area, many of which were grazing on the Fairhaven section of Upton Marshes on 1 January. A large flock of about 3,000 lapwings, with 200 golden plovers, occupied mainly the arable fields across the river on St Benet’s Level. 7 Bewick’s swans and 9 black-tailed godwits were seen on the reserve, and the following day ruffs peaked at 22, accompanied by two dunlins. A green sandpiper on 8 January was the only sighting until the Spring. In mid-January 2013, a fall of snow marked the start of three months of cold easterly winds during which time numbers of birds on the marshes remained constant. This January was unusually mild and wet, and by the middle of the month many of the birds had dispersed. Two shelducks and a redshank on 11th and two oystercatchers on 12th were possibly early arrivals at their breeding ground. Away from the marshes, Great Broad attracted higher numbers of teals than usual, with max. 606 on 11th, and ducks included a pair of pintails on 19th.

The latter part of winter was characterized by regular sightings of birds of prey - a peregrine, one or two buzzards, two hen harriers (one being a strikingly-beautiful adult male), kestrels, sparrowhawk and marsh harriers. Barn owls were noticeably less frequent than usual. 

Gadwall, photo by Elizabeth Dack

Through February and early March some of the potential marshland breeding species hung around - shelducks (max. 3), redshanks (max. 11) and oystercatchers (max. 2). A merlin was seen briefly on 28 February. Three stonechats on 4 March were the only ones seen during the winter. A bittern was beside the river on 20th. Although groups of lapwings inhabited the marshes throughout this time, it was only during the second half of March that territories were occupied by individual pairs. A pair of buzzards took up residence in the wet woodland. At the end of March, up to 50 gadwalls were present, most being on Boat Dyke Marsh. In the fen, chiffchaffs and blackcaps were heralding in the spring, and a pair of bearded tits was seen in the improved reedbed after an absence of many years.

NWT Upton Broad & Marshes: Birdlife October to December

Nigel Robson, Volunteer Bird Recorder for NWT and Mark Crossfield, NWT assistant warden for Bure and Ant

In October, major conservation work to all the grazing marshes was resumed and completed at NWT Upton Broad and Marshes by the end of 2013. The network of foot drains - long narrow lines of shallow water snaking across the grassland delivering fresh water from the existing system. With increased water levels the landscape transformed into a wetland attracting wintering wildfowl. The combination of flashes of open water, inundated grassland, shallow foot drains and dykes with gently-sloped edges is the culmination of long-term management objectives. The number of birds feeding on the grazing marshes continues to increase.

In recent winters, pink-footed geese have rarely settled on the marshes, despite large numbers roaming between arable fields in the area. November saw small groups for the first time visit consistently, and by the second half of December, over 1,000 could be seen grazing the very wet Boat Dyke marshes. The relatively close proximity of groups of walkers, many with dogs, using the river bank path did not disturb the feeding geese. This area also attracted good numbers of lapwings, frequently around 500. Over the marshes as a whole, plus the lands immediately across the river, over 2,500 had accumulated by the year end. Other groups of waders on the wet marshes were black-tailed godwits (max. 22 on 20 Dec), ruffs (max. 20 on 27 Dec) and golden plovers (max. 90 on 29 Dec).
 

During daylight hours very few duck had been present on either the marshes or the river lagoons since mid-November (up to 18 shovelers were at the lagoons prior to that). Usually there were no more than a few teals and mallards and a pair of gadwalls despite some 350 wigeons on neighbouring marshes.  Through monitoring g we have discovered that during darkness, the situation is quite different. The wet marshes were invaded by a variety of species, best identified by their frequent calling. During December nights, these included wigeon, teal, mallard, greylag, Canada, Egyptian and pink-footed geese, lapwing, golden plover, snipe and woodcock. Through night-vision optics, birds were seen distributed over the entire marshes.

The corvid roost in the wet woodland at the Doles continued to comprise several thousand Rooks and Jackdaws. Although  an extensive area of this woodland had been removed during the last two winters to reclaim fen, the roosting birds merely re-located to adjacent stands. Another evening and early morning spectacle was the flight of the Cormorants en route between the coast and their roosting trees beside NWT Ranworth Broad. 704 were counted at first light in mid December.

Increasingly cranes have featured in winter. Throughout October and November, a group active in the Bure Valley concentrated at the reserve and St Benet’s Level (there utilising ploughed land). Their number varied, usually 12 to 25, with a maximum 34 on 16 October. Rather fewer were seen in December.

The marsh hedgerows provided an abundance of berries, which drew variable numbers of winter thrushes. A peak of 550 fieldfares arrived around 23 December and foraged in the hedgerows and on the wet grassland. A small number of bullfinches were, as usual at this time, located in these hedgerows.

Also wintering in and around the reserve were two redshanks, a peregrine (two in mid December), barn owls, marsh harriers, a hen harrier and a buzzard. A snow bunting was beside the river on 10 November, the same day that 12 whooper swans flew across the reserve and landed briefly on St Benet’s Level. Three dunlin were on the marshes on 14 November and a curlew on the 16th. A small number of bearded tits stayed concealed in riverside reedswamp, occasionally venturing into reed-fringed dykes. A drake goosander on the river lagoons on 14 December was an unusual visitor.
 

Over the last few years, several habitats in the reserve have been subjected to extensive modifications. The river bank was raised and in places re-positioned, the river lagoons were created, the grazing marshes and dykes configured to allow control over higher water levels and permanent water bodies, the reed bed adjusted with more open areas and deeper water to suit bitterns, scrub and carr woodland reduced to increase the extent of herbaceous fen, and Little Broad mud-pumped to improve its aquatic diversity. Permissive paths have been extended and widened to afford visitors greater opportunities to access all sections of the reserve. Over the next few seasons gradual changes in the vegetation are expected where these major interventions have occurred, and it should be an exciting time for the naturalist to observe how the flora and fauna responds.

Half moon highlight

Chris Durdin, NWT Thorpe Marshes

caddisfly Limnephilus flavicornis

 One of the challenges of recording wildlife at NWT Thorpe Marshes is that the penny has dropped that I know rather little about a lot of wildlife, especially invertebrates.

Happily, help is on hand with the NWT’s Wildlife Information Service. It helped me last October when on one our monthly guided walks there were hundreds of brown insects flying around, especially on the edge of the gravel pit, St Andrew’s Broad. I worked out that they were caddis flies. In response to a photo, I learned they were probably

Limnephilus flavicornis, known by anglers as 'cinnamon sedges'.

Most of us have heard about the extraordinary underwater cases of caddis fly larvae: using sticks or stones to protect themselves from predators. Seeing them is a different matter.

The synchronised emergence of adult caddis flies is one opportunity, a literally short-lived phenomenon when the adults mate, lay eggs in the water or overhanging vegetation, and die. Looking again at my photos, I see they lack the proboscis of a moth: most adults don’t feed.

Well, it happened again last Sunday, 6 October. Dozens of what looked like brown moths were fluttering clumsily around, landing on rushes and other vegetation.

Limnephilus lunatus

This time, having looked carefully at a photo, I am suggesting an ID without the help of the Trust’s expert. I think it is the rather similar Limnephilus lunatus – the lunatus specific name coming from the half-moon shape at the end of the wing. But I’m happy to hear from any NWT blog readers who know better!

For help with identification, you can email photos to wild@norfolkwildlifetrust.org.uk

More wildlife news from NWT Thorpe Marshes and details of monthly walks on http://www.honeyguide.co.uk/thorpemarshes.htm

Chris Durdin

May and June at Upton Broad and Marshes

Nigel Robson, Volunteer Bird Recorder for NWT and Mark Crossfield, NWT assistant warden for Bure and Ant

During May and June the birdlife at NWT Upton Broad and Marshes was characterised by continuing spring passage and breeding.

A wheatear was noted on 4th May and lesser whitethroats on 4th and 6th. The last few golden plovers passed through in the first week, but whimbrel numbers remained high with 42 on 4th and the last being noted on 25th. At the river lagoons two wood sandpipers stayed from 5th until 10th, whilst ringed plovers (max. three on 11th), dunlins (max. 13 on 11th), greenshanks (max. two on several days) and common sandpipers (max. two on 25th) were the waders regularly seen on passage. A pair of little ringed plovers occupied the area and a pair of avocets visited occasionally. Meanwhile the lapwings, redshanks and oystercatchers were breeding in the suitably-wet grazing marshes.

 

Yellow wagtail, photo by Mark Crossfield

A drake garganey was seen on 5th and 13th. Shovelers, gadwalls, tufted ducks, pochards and a pair of teal were present as potential breeders. One pair of shelducks had eight small ducklings on 25th but these were not found subsequently. The usual few pairs of Egyptian geese were breeding and, perhaps less welcome, there were many greylags following last year’s influx.  Other breeding birds in the reserve included two pairs of yellow wagtails and single pairs of hobby and marsh harrier. A bittern booming just outside the reserve boundary on 5th may have been an un-mated male, but it was a hopeful indication that the reedbed within the reserve, currently being improved to attract bitterns in time for the 2014 breeding season, has a fair chance of early success.

Perhaps affected by the late spring, some passage continued into June. On 5th, a male red-backed shrike was found in the marshland bushes, and three ringed plovers and two common sandpipers were at the lagoons. The pair of avocets put in an appearance on 6th, along with two little gulls, by which time a redshank was seen to have chicks. A curlew was present on 17th and three green sandpipers on 24th.

In the fen carrs, one or more woodcocks roded overhead throughout the month at twilight, and a single Turtle Dove, rarely found in the reserve nowadays, was “purring” on 20th. From reeds just outside the reserve boundary a male bearded tit was calling on 30th, possibly indicating breeding. It is hoped that this species, like the bittern, will also benefit from the modifications to the reserve reedbed. Cuckoos could be heard throughout the month, and one on 23nd was seen to have a small tracking aerial attached. It had been tagged under the BTO cuckoo tagging project and would have been either “Nelson” or “Ken” as both were transmitting their presence in the area at the time. Two others cuckoos seen on 24th were not tagged.
 

Leucistic swift, photo by Mark Crossfield

Two abnormally-plumaged birds occurred and were photographed in flight by Mark Crossfield. A leucistic swift was overhead on 19th May, and an albinistic starling was amongst the flock on the marshes on 9th June.

Starling, photo by Mark Crossfield

Spring at Upton Broad and Marshes

Nigel Robson, Volunteer Bird Recorder for NWT

Birdlife at Upton from February, through March and well into April reflected little change due to persisting cold easterly winds. Mark Crossfield of the reserve staff now regularly watches birds at Upton and his records are combined with mine for this and future posts.

The wintering pintail was last noted at the river lagoons on 14 March, at which time oystercatchers arrived in their breeding ground, six weeks later than the shelducks. Gadwalls were assembling on the grazing marshes, peaking at 48 on the 26th, and at the same time shovelers were gathering on Great Broad, with a maximum of 20 on the 24th. A few dunlin passed through, including a group of seven on the 26th. Teal remained the most numerous duck at the marshes with some 200 staying into April, by which time a few Wigeon had joined them.

After a paucity of starlings on the grazing marshes during the winter months, hundreds appeared on 28 March. The wintering peregrine was there to take advantage, once causing the flock to rise in a spiralling cloud before diving in from above - and moments later making off low with a bird in its talons. Other raptors regularly seen were a resident pair of marsh harriers, a recently arrived pair of buzzards in the woodland, sparrowhawks and kestrels. Barn Owls appeared not to be reduced in number despite reports throughout the country of a high mortality during the cold weather, though they tended to keep hunting throughout the day which may be an indication of reduced availability of prey.

The anticipation of spring was finally realized in mid-April with the sounds of chiffchaffs, soon followed by blackcaps, whitethroats, sedge, willow and grasshopper warblers, and finally reed warblers. The cuckoo was back before the end of the month, as yet remaining a familiar sound across the marshes every spring.

Pairs of waders occupied their territories on the marshes. Conditions were not as optimal as had been hoped after the ample winter rainfall, high winds causing water in some shallow scrapes not linked in with the dyke systems to evaporate quickly. Nonetheless the lowest grazing marshes attracted some 8-10 pairs of lapwing, three of redshank and one each of oystercatcher and little ringed plover.
 

Whimbrel, photo by Lawrie Webb

Some of the regular passage migrant species were well represented towards the end of April, and others less so. There is always a strong passage of whimbrel at Upton, and this spring a steady build up of numbers reached 73 on the 28th. Unlike last year, no bar-tailed godwits were seen amongst them. A pair of pintail was present at the river lagoons on the 21st. A pronounced fall of migrants on 27th included many yellow wagtails (including blue-headed forms), two white wagtails, seven wheatears, a whinchat and a stonechat on the marshes, and four ring ouzels and a lesser whitethroat in the tall hedgerows.  Up to 34 golden plover were well concealed in an adjoining wheat crop for several days during this time. Waders stopping on passage on the exposed mud of the tidal lagoons were fewer in number and variety this April than last (the first year of the lagoons existence) with a few snipe and the odd common sandpiper and greenshank. Visually the conditions seemed favourable enough – possibly invertebrate richness has reduced after the first spring following the laying down of the dredgings, or there may simply have been fewer birds about during so late a spring.  

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.

Totting up the Upton Birds

Nigel Robson, Volunteer Bird Recorder for NWT

NWT Upton Broad and Marshes, photo by Richard Osbourne

In support of conservation work at Upton Broad and Marshes, I have recorded birds there regularly since 2006 to ascertain their status and relative abundance. Very little has been published on the ornithology of this area.

Initially I set out to establish a status quo before major management works to improve site conditions for breeding waders and wintering waterfowl took effect. The results of this part of the study will be in my paper entitled “The Conservation Value and Population Status of Birds at Upton Broad and Marshes 2006-2011” in the forthcoming Transactions of the Norfolk & Norwich Naturalists’ Society (Vol. 45 Part 1).

The present phase of the study is monitoring changes in the birdlife after 2011. This should help determine the effects, successful or otherwise, of habitat modifications. Birds are useful indicators of environmental changes because they come and go freely, and are relatively easy to see, hear and identify. In my posts for NWT’s blog I intend to focus on this aspect, starting with setting the scene, and giving a brief resume of how bird activity in 2012 differed from the preceding years.

The reserve has two distinct but inter-related ecosystems, separated by a marsh wall (bank): undrained fen, which includes broads and carr, and drained grazing marsh. The habitat modifications affect mainly the grazing marshes. Here water levels are being raised in various sections, and areas of standing water introduced with foot drains and shallow ponds. Grazing regimes are developing to produce swards benefitting wildfowl, cranes and waders. Separately but concurrently, river defence work has created tidal lagoons, with muddy banks that are gradually vegetating to form reed swamp communities. In the undrained fen, wet woodland is being reduced to substantially increase herbaceous fen habitat, and the small (and only) reedbed is being improved for Bitterns by widening dykes within it and grading their banks to vary reed densities. The smaller of the two broads, Little Broad, has been lightly mud-pumped to partially increase its depth and release from the silt seeds of a past aquatic flora for regeneration.  

Lapwing, photo by Maurice Funnell

2012 was the first year when the habitat modifications to the grazing marshes clearly showed results. Early in the year the new areas of standing water quite soon attracted Bewick’s Swans (up to 80) and an occasional group of Pink-footed Geese including a few White-fronted Geese. Grazing duck, however, remained scarce despite a maximum of 400 Wigeon frequenting the adjacent St Benet’s Level. Winter visitors seen from time to time included a small group of Cranes and single Hen Harrier, Peregrine, Merlin and Short-eared Owl. Spring arrived as a drought-gripped eastern England, but in spite of this the grazing marshes retained some of the standing water. Consequently there was a marked increase in breeding waders: Lapwings (13 pairs) and Redshanks (4-5 pairs) doubled their number from the previous few years and Oystercatchers (3 pairs) were at their previous maximum. Single pairs of Avocet and Little Ringed Plover bred close to the river on newly created open ground, but this feature is unlikely to be retained as reed swamp takes over.

Passage waders also increased, both in numbers and variety. On the grazing marshes Whimbrel reached over 50 in April/May, some days accompanied by a few Bar-tailed Godwits and occasional Curlew (the latter occurs more frequently in autumn and winter). During the same period a few Golden Plovers (northern race) and Ruff passed through, and a pair of Black-winged Stilts even stayed for a while. But it was the riverside tidal lagoons, not yet vegetated, that attracted the greater diversity of species in both spring and autumn: Common, Green and Wood Sandpipers, Greenshanks and Spotted Redshanks, Dunlins, Curlew Sandpipers, Little Stints, Sanderlings, Ringed Plovers and a single Grey Plover.

The prolonged rainfall that followed the spring drought contributed to disappointing breeding outcomes for most of the waders. Some warblers, notably Whitethroats, Sedge Warblers and Reed Warblers, were down in numbers. Duck, however, were more successful than previously: Shelduck raised ducklings, and pairs of Gadwall, Shoveler, Teal, Tufted Duck and Pochard were present in summer and may have bred.

With rainfall consistently high throughout the first half of this winter season, the marshes are very wet. Wintering waterfowl (geese, ducks, Lapwings and Golden Plovers) have been fewer in number than during many of the winters preceding the habitat modifications. However, Bewick’s Swans have maintained a sizeable group (120+) and Cranes have been at their maximum (17). The unmodified tall hedgerows in the marshes attracted good numbers of winter thrushes early on and a few Waxwings in December. The second half of the winter may produce a different scenario!