A History of No. 6 tank (part 3)

The first occurrence of breeding Black-winged Stilt in Cheshire by Ted Abraham

No6 tank through its deveoplement by Bill Morton (13)

The excavated scrape/pool where the Black-winged Stilts eventually settled to breed (flooded area at the left hand side of the picture). In the foreground is Martin Gilbert’s tent which he used to observe/record behaviour and also discourage potential egg collectors.

Black-winged Stilts doodle. Bill MortonA party of three birds-male, female and white-headed immature male – was found by Ken Croft near Cemlyn Bay on the North Anglesey shore at 15.15 hrs on 10th April. The birds were feeding in flooded fields alongside the track to Ty Lian Farm to the West of the main Cemlyn Lagoon. They remained here to dusk on 21st April. Display and attempted copulation were observed and it was thought possible that the adult birds might attempt to breed. However after a clear night, there was no sign of them on 2nd. During their 12 day stay in the same wet fields the birds were enjoyed by over 1000 birders, some travelling from as far afield as Scotland and the Home Counties and there was excellent footage of the birds on Welsh television.

 At 09.40 hrs on 22nd April, the same party of three birds was seen to fly in from the West to Inner Marsh Farm RSPB Reserve. Here they remained, chiefly favouring No 2 Lagoon on until 18.40 hrs, 24th when they circled high and departed purposefully West. Remarkably they returned at 1920 hrs and remained to dusk but there was no sign of them early next morning.

 At 0900 hrs 25th, the birds were relocated at Elton Hall Flash, Sandbach where they remained to 10.00 hrs. They were refound at Frodsham Marsh New Workings at 1545 but seemed unsettled and flew off high to the North towards the nearby Mersey Estuary at 16.45. The birds must have executed a sharp left turn for at 17.00 hrs – only 15 minutes after departing Frodsham – they flew back in again at Inner Marsh Farm!

Pencil field sketch of nesting Black-winged Stilts, No6 tank, frodsham Marsh. 1993. Bill Morton

 Many observers were able to obtain remarkable up close views of the stilts from the hide at Inner Marsh Farm over the next ten days. Again display and attempted copulation and, sometimes, the immature joined in as well! They remained on the reserve until dusk on 4th May but could jot be found anywhere on 5th May. On 6th May the three birds were outside our region to Weldrake Ings (North Yorkshire) where they stayed until departing NW at 20.00 hrs.

The birds flew in yet again to Inner Marsh Farm RSPB Reserve at 10.30 hrs on 8th May – a nice bonus for teams engaged in the annual ‘Cheshire Bird Race’. This time it really seemed as if the pair of adult birds were serious about nesting and they established a territory, which they defended vigorously against the local Coots, Tufted Duck, etc, on a small islet in No 2 Lagoon immediately in front of the hide. For wardening purposes they could not have chosen a better site anywhere in the North West. Nest scrapping began on 10th. The RSPB North West Regional Office finalised their plans for a round-the-clock wardening scheme and the birds were still present and looking almost certain to nest late evening 13th with wardening to start next morning. The morning of the 14th however presented a problem – the pair had departed overnight and only the white-headed bird remained.

Black-winged Stilt nest site, No 6 tank, Frodsham Marsh. May-June 1993. Tom Edmondson.

 The pairs were presumed to have arrived at Frodsham Marsh early on 14th and here they quickly established territory around a minute and unstable mud islet in the near left hand corner of the third pool of the ‘New Workings’. These pools had been formed during the construction work being undertaken by the Manchester Ship Canal Company to build a sixth vast lagoon to accommodate sludge from the canal and in mid May work was at a critical stage with near continuous procession of massive diggers and dumper trucks passing close to the birds chosen nest site. The water level in the pools, although not too deep for the birds at this stage, was subject to sudden rapid fluctuations and could not be controlled. The birds had finally settled for a site that presented many potential problems – ease of access for egg thieves, disturbance by construction traffic  and risk of flooding should the weather deteriorate!

 The white-headed bird moved to Frodsham 15th but did not associate freely with the pair and preferred to feed alone on the fourth pool of the New Workings or at the flooded East end of the No5 Sludge Pool even making a return visit to Inner Marsh Farm evening of 19th.

Black-winged Stilt, No6 tank, Frodsham Marsh. Bill MortonThe first egg was probably laid on the mud islet on 16th since incubation began on 19th. “OPERATION STILT” swung in to action and the RSPB NW Office appointed local birder Martin Gilbert as warden. Martin began his vigil on 20th with a tent but a caravan arrived on site on 22nd. Everything went smoothly in the early stages and Martin’s daily log reflects this: “Monday 24th May 04.55 hrs – M left nest mobbing crow s. 05.22 hrs – Changeover. 06.14 hrs – F left nest mobbing crow. 06.25 hrs F turned eggs. 06.48 Changeover.” and so on. The incubation continued without any real problem until 26th May when heavy rain began to fall and went on falling for the next four days.

west side of the Black-winged Stilt nest site, No 6 tank, Frodsham Marsh. May-June 1993. Bill Morton.   30053 010693.

 The water level in the pool could not be prevented from rising, despite the best efforts of helpful MSC staff to open drains, and crisis point was reached around 14.45 hrs on 30th May when it was lapping within a centimetre of the nest. Very courageous action was undertaken by RSPB Warden Colin Wells and Martin Gilbert who waded out into the deep pool, with unstable soft mud base, and managed to raise the water level by about 20 centimetres. Incubation resumed immediately.

Black-winged Stilt, No6 tank, frodsham Marsh. April 1993. Bill Morton

 Although the male and female shared incubation more or less evenly in the early stages, the male was now spending increasingly long periods away from the nest site – either at the East end of No5 Sludge Pool or on the Mersey Estuary. The female had to leave the nest to feed herself of course and with the male now reluctant to take share of his responsibilities it was inevitable that the eggs were sometimes left unincubated – once for a period as long as 73 minutes. It was predated by Magpies at 13.48 hrs on 31st May.

Black-winged Stilt nest site, No 6 tank, Frodsham Marsh. May-June 1993. Bill Morton.....007..

 The female mainly, and the male occasionally, continued incubation until 05.48 hrs 4th – 17th June day of incubation – when the female left the nest for the last time. At 09.50 hrs, one egg was taken by a Coot and not long after the fourth and final egg was taken by a Magpie. The brave breeding attempt by ya pair of Black-winged Stilts in Cheshire had failed. Predation was the secondary cause of failure. The primary cause was the British weather climate. Heavy rain had caused elevated water levels in the pool which could not be controlled and which disrupted the behaviour of the birds to such an extent as to cause periods when the nest was left unguarded.

Black-winged Stilt nest site, No 6 tank, Frodsham Marsh. May-June 1993. Bill Morton. 006...

 The conservation department of the RSPB North West Regional Office are to be congratulated for the tremendous team effort that they organised so efficiently throughout “Operation Stilt”. In particular, Dr Andre Farrar (Conservation Officer), Colin Wells (Dee Estuary Warden) and Martin Gilbert put in many long and tiring hours well beyond the normal call of duty. We must not forget either the team of voluntary wardens who assisted during the cold dark hours of night with their torches and mobile phones including Geoff Clarke, John Dolby, Paul Hill, Bill Morton, Ken Stoba, Rob Stratford and many others including Mike Wellman of the Cheshire Constabulary. Their efforts were not in vain since it proved that when the need arises then North West birders will rise to the occasion and many valuable lessons will have been learned to put into practice should a similar operation be needed to be mounted in the future. It was particularly pleasing that it was possible to publicise the presence of the birds in Frodsham throughout their stay on Birdline North West thus enabling a great many birders to observe the daily routine of the nesting stilts. Viewing from the raised dirt road which runs alongside the New Workings from which the birds could easily be seen without the least fear if disturbance. The near continuous procession oc birders along this road seems likely to have been a major disincentive to any potential egg collector.

 On 4th – 7th June, the party of the three stilts were back together again as they had been in the beginning and they could be seen feeding, apparently contentedly as if nothing untoward had happened, in then lushly vegetated and flooded SE corner of No 5 Sludge Pool, about half a mile from the nest site. But somehow their actions and demeanour lacked the sense of urgency and hyperactivity they had exhibited on that day two months previously when they had first arrived at Cemlyn. Your report writer had been used to seeing the stilts almost daily for nearly two months. It came as a real shock to make an early morning visit to Frodsham on 8th June and find that they had at last departed. We soon learned that they had flown South and all three birds had arrived at Radley Gravel Pits in Oxfordshire later that day where they remained to at least 19th June.

Ted Abraham

Abraham E J. 1994. North West Region Bird Report 1993 (Birdline North West), pp 20-24.

Illustrations/field sketches by WSM. All photographs WSM except for # 2 which was taken by Tom Edmondson.

To be continued…

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