Back in 1969 numbers were quite low as the birds were only just making a slow recovery from the harsh winters of the early 1960's which saw much of their chief prey, cockles and mussels, wiped out. I well remember the ice floes on the estuary, and week after week of lying snow, during early 1963. Seems incredible now after the long run of mild winters we've had recently.
Counts increased from a low in 1970 of 7,355 to 42,505 in 1981. From there the five year moving average stabilised around 30,000 to 35,000 before beginning a decline in the 1990's to a minimum of 12,506 in the winter of 99/00. The last three winters have shown a steady increase and in December 2004 numbers reached 25,944, with the five year moving average moving back over the 20,000 figure. The reasons for the decline since the 1980s are no doubt complex involving many variables such as the availability of cockles, disturbance, breeding success and weather. These factors are important not only as they relate to the Dee Estuary, but also to other estuaries. So if Morecambe Bay is suffering from excess disturbance, for example, the Oystercatchers might well be inclined to move here, and vice versa. But probably the main impact on numbers has to be the amount of cockles on the estuary. This may well be due to over exploitation of the cockle beds when cockling was virtually a free for all in the late 1980's and 1990's. It would seem that a large amount of damage to the estuary occurred over this period, not only to the cockle beds themselves, but also to the eco-system as a whole with tractors and people all over the mudflats. The figures speak for themselves - in 1987 16,000 tonnes were harvested but in 2003 only 1,182 tonnes (although even this was valued at £700,000). During the last few years the Environmental Agency have been more effective in controlling both the amount of cockles taken and the damage cockling does to the estuary so it is surely no coincidence that we have seen an increase in Oystercatchers over this period. A lot more can be done and the Environment Agency are currently trying to bring in a Regulation Order which would more effectively control cockling, hopefully benefiting both local cocklers and Oystercatchers. The impact of cockling and Oystercatchers on each other is not as straightforward as it may seem and I don't intend to go in to it here - but see sources of information below.
Oystercatchers are present on the estuary all year round. Those here from April to July will be mainly immature birds, they don't start breeding until they are at least four or five years old. Oystercatchers are also one of four species of waders to breed around the estuary, albeit in only small numbers (Redshank, Ringed-plover and Lapwing being the others). I always see two or three pairs at Gronant whilst wardening the Little Tern Colony - and they are very effective at chasing away egg hunting crows! The first birds to return to the estuary in early August will be those that have bred in this country, followed by those from Norway, Iceland and the Faeroes, so by September we usually have the highest count of the year. High numbers are present all winter before they return to their breeding grounds during February and March. In the graph above I've included the 1991/92 winter for comparison as this was the last time we had a count of over 35,000.
The map and table above gives an indication of how Oystercatchers distribute themselves across the estuary. They are, in fact, our most widespread wader being found throughout the estuary and North Wirral Shore but mostly concentrate in the areas shown. There are also usually several hundred feeding in the fields around the estuary, particularly at high tide. Low tide is a time when birds can feed on exposed cockles and mussels, but at any one time up to a half their number can be viewed resting (or loafing as BWP puts it) in tight flocks - in effect low tide roosts. With the relative large food items the Oystercatchers consume they can afford to conserve their energy in this manner.
I took the above photo whilst wardening at Point of Ayr in October 2004. It was a lovely day and I remember how the Oystercatchers flew just a few feet above our heads on their way from the beach to their roost on the shingle spit opposite the RSPB hide. At high tide a Peregrine disturbed them and the whole flock of about 4,000 birds took off noisily and wheeled round above us for about 10 minutes before settling - a spectacular birdwatching experience I'll never forget.
Wetland Bird Survey Data in this article should not be used in any way without permission of the WeBS Office. To access official WeBS data please contact the WeBS Office - BTO, The Nunnery, Thetford, Norfolk IP 24 2 PU, http://www.bto.org.
Sources of Information for this article:
1. Wetland Bird Survey Data (Core Counts) 1970 to 2003, kindly provided by Andy Musgrove of the BTO.
2. Wetland Bird Survey Data (Low Tide Counts) 1996 to 2002, kindly provided by Alex Banks of the BTO.
3. Neil Friswell and Colin Wells, Dee Estuary Wetland Bird Survey Reports, 1999/2000 to 2003/2004.
4. Deeside Naturalists' Society who kindly provided counts from Connah's Quay and Oakenholt.
5. Martyn Jameison who kindly provided counts from Heswall.
6. Stanley Cramp (Ed), The Birds of the Western Palearctic, RSPB, 1977.
7. Migration Atlas, BTO, 2002.
8. A.J. Prater, Estuary Birds, T&A D Proyser, 1981. See pages 112 to 114 for cockling and Oystercatchers.
9. W.G. Hale, Waders, New Naturalist, 1980. See Chapter 13, Cockles and Conservation.
10. Liverpool Daily Post, February 12th 2005, 'Cockler crackdown looms as stocks fall' by Kirsti Adair.
11. My own observations and many birders who have kindly sent their data to me, including the Dee Estuary Voluntary Wardens.
Richard Smith (thanks also to input by Andy Musgrove and Neil Friswell)..
Richard Hurst (RSPB)
March Bird News
several weeks of cold north wind the wind went round to the south around
the middle of the month and within a day we had our first Wheatear.
As always with Wheatears once they start coming in they come in droves and
we had 20 on
Island by the 20th. In fact both the 19th and 20th were ideal for
migration - SE wind with slight mist - and it was more like the height of
the migration in April on Hilbre
Island with loads of birds coming through including over 800 Meadow Pipits
and 70 Fieldfare. As can be seen in the table below the dates of first
sightings was in line with recent years, although the Swallows were a bit
late and we are still to see our first House Martin. We also had an early
Ring Ouzel (21st) and Osprey (25th).
After two years of disappointing high tides at the Parkgate High Tide Birdwatch events we have struck lucky this year with two more excellent days, in particular on the 11th the tide really roared in with one of the highest tides of the past few years. As well as good birds (at least four Short-eared Owls) we always get some good views of mammals on these big tides and one had to feel sorry for this poor young fox trapped by the tide and too scared of the watching birders to make a run for it.
Of course Parkgate isn't the only place to see the tide and the photo below was taken at Burton Marsh where we can normally see the Decca Pools, a rare sight to see all these acres of grass covered by sea water.
Talking of Decca Pools, a Dartford Warbler was reported being in a hedge close by on the 20th. Unfortunately it was after dark before the news really got out, and unfortunately there was no sign of it the next day. The two Cetti's warblers at nearby Neston Reedbed were confirmed but somewhat elusive with only a handful of birders getting a good view.
The long-tailed duck at West Kirby stayed until the 7th and the drake Green-winged Teal at Inner Marsh Farm was seen several times, a drake Smew and female Goosander were also there briefly. 40 Brent Geese on Hilbre Island was the highest number ever recorded there for March. Wader numbers were still high on their West Kirby roost early in the month (approx 12,000 total flock) but not unexpectedly had drifted away to almost zero by the end. Two Avocets landed at Inner Marsh Farm on the 24th although only one was seen a few days later.
Last but not least a very nice female Black Redstart was observed during the last few days of the month in the back gardens of Stanley Road, Hoylake.
What to expect in April
After the trickle of migrants in March the spring migration really starts with birds pouring in during April. We will have our first Swifts, Sedge Warblers, Grasshopper Warblers and Whitethroats among others. Something I look forward to is the return of the terns although neither the Common Terns at Shotton or Little Terns at Gronant will seriously get down to breeding until May. Out to sea there will be a good passage of Sandwich Terns and Gannets, perhaps with their attendant Skuas although these tend to be much less common than during the return passage in late summer.
Both Ospreys and Marsh Harriers pass through the estuary on their way north. Marsh Harriers tend to hang around more and are thus much easier to see than the elusive Ospreys which usually go over without stopping. Although the number of waders on the estuary is generally low they too are migrating and large flocks of Knot and Dunlin are on their way north. I always look at these flocks in awe knowing the distances they travel. The birds that come through here in April winter in Africa - the Knot breed in the high arctic of Siberia whilst the Dunlin are on their way across the Atlantic to Iceland and Greenland. Whimbrel are on a similar migration but in much smaller numbers, wintering in Africa and breeding in Iceland and Scandinavia, we usually see a few flocks of 5 - 10 birds. The Black-tailed Godwits that spend the winter here in ever increasing numbers breed in Iceland. Many will still be on the estuary this month looking magnificent in their breeding plumage.
With the migration in full swing just about anything can turn up, last year we had a Hoopoe and White Stork on the same day!
Many thanks go to Nick Moss, David Small, Clive Ashton, Allan Hewitt, Bill Owen, Joseph Wynn, Iain Douglas, Roy Palmer, Colin Jones, Dave and Emma Kenyon, Ray Roberts, Bernard Machin, Steve Edwards, Charles Farnell, Steve Williams, Chris Butterworth, Martyn Jamieson, Eric Sherry, Jane Turner, Phil Woollen, Allan Conlin, Steve Ainsworth, Mike Hart, Steve Wrigley, Neil Friswell, John Roberts, Steve Round, Chris Wilding, David Haigh, Barry Griffiths, Bill Potts, Neil Lewis, Colin Wells, Richard Hurst, Damien Waters, Geoff Watkin, Dave Burry, T. Mansell, Tanny Robinson, Kevin Hayes, Steve Roberts, Frank Huband, Mal Smerdon, Matt Thomas, Colin Schofield, John Carter, J.A. Williams, John Campbell, Gerard McLoughlin, Mark Feltham, Kevin Smith, Arthur James, John Kitchen, Nigel Troup, Pauline Moulton, the Dee Estuary Voluntary Wardens and the Hilbre Bird Observatory for their sightings during February. All sightings are gratefully received.
April Highest Spring Tides,
9th April, 12:33hrs 10.0m. Times BST.
10th April, 13:11hrs 9.9m.
Forthcoming Events (organised by the
Wirral Ranger Service,
Flintshire Countryside Service and/or the RSPB):
Saturday 9th April, 11:00am, Parkgate
Saturday 23rd April, 9:30am, Flight of the Godwits.
Sunday 1st May, 5:00am – 7:00am, Dawn Chorus for Commoners.
Note: Many of these forthcoming events are extracted from the 'Birdwatchers Diary 2005', which covers both the Dee and Mersey regions. Hard copies available from the visitor centre at Thurstaston, Wirral Country Park 0151 648 4371.
All material in this newsletter, and indeed the whole web site, has been written by myself, Richard Smith, unless specified.
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