CHESHIRE HAS LOST ONE OF THE UK'S TOP TEN WETLANDS!
Follow this link for the 2015 count dates and this link for a map of the recording areas.
It is true that Cheshire used to have two of the top ten wetlands in the UK for overwintering wildfowl and waders. For many years the Dee estuary has been the 7th or 8th most important wetland for waterfowl, while the Mersey has ranked 9th in the country. However, as table 1 shows, since 2007 the Mersey has dropped out of the top ten and is now ranked 17th, while the Dee has remained at number 7.
Table 1: 5-yearly average of Waterfowl on the Mersey Estuary and Dee Estuary
At the CAWOS meeting on 7th October 2011 Neil Calbrade (WeBS Research Ecologist, BTO) gave a very interesting talk speculating about why numbers of birds on the Mersey seem to have fallen recently. Between 1996 and 2006 I helped with the monthly waterfowl counts on the Mersey so I was keen to find out why the numbers had fallen so sharply since I'd stopped, surely I wasn't to blame!
Neil said that there had been an increasing general trend for birds flying from Siberia and Europe for the British winter to stay on the east coast rather than move onto the west coast. This is probably due to milder winters meaning it no longer pays to move to the west coast, and this could be the reason why numbers of birds on east coast wetlands have increased while those on the west coast have fallen.
How do we know this?
We know this because each month, on a particular day, birdwatchers count the waders and ducks present on every wetland in Britain. The counts, known as the Wetland Bird Survey (WeBS) are coordinated by the BTO and provide a massive data set (see http://www.bto.org/volunteer-surveys/webs/publications/annual-reports). Each year, they produce an annual report that summarises for each species and wetland the numbers of birds present each winter and gives a rolling 5-year average for sites and species. This means that the effect of unusual events or counts do not distort the data.
I have used the WeBS count data to look at the top estuaries and tracked the number of wintering birds from 1995-96 to 2009-10. There is a clear trend: west coast estuaries have been losing birds, while those on the east coast now hold more birds. Table 2 shows Britain's top wetlands and how those rankings have changed since 1995-96. Two estuaries on the east coast, north Norfolk and Breydon Water, have shown a remarkable 143% increase while two wetlands in the west, the Mersey estuary and Lough Neagh, have shown very significant declines. So it would seem that there is a clear trend and the Mersey is being affected by this, more than most other west coast estuaries.
Table 2: Britain's Top Wetlands - Wintering Birds
Why are bird numbers falling on the Mersey?
Since the CAWOS meeting I have rejoined my friends counting on the Mersey and they have confirmed that several species have shown very significant declines. Table 3, below, shows that species like Wigeon, Pintail, Golden and Grey Plover have declined and are no longer of National Importance. Other species like Teal, Black-tailed Godwit, Redshank and Dunlin have all declined significantly but are still of International or National Importance
Table 3: Bird Species of National Importance that use the Mersey Estuary
# 1999-2000 figure
The BTO are concerned about these declines and have issued alerts for 11 of the 12 key species that winter on the estuary (see www.bto.org/webs/alerts). No one knows why the declines have occurred. We know that over this time period pollution levels have fallen. Has a cleaner estuary meant fewer birds? Cleaner water should mean more fish and we know that salmon have now returned to the River Mersey to breed, so it is surprising that a fish-eating species like Great Crested Grebes have also declined. There may be other man-made factors that we cannot detect, or perhaps just natural changes in the proportions of salt marsh and mudflat and their position in the estuary. Certainly the main channel is very active and since my visit in January 2006 and my last visit in October 2011, the spartina in Manisty Bay has increased at the expense of mudflat. It is hard to see that recreation has had much impact as the south side is still cut off from the outside world except for a few wildfowlers and the monthly duck counters.
We do know that there is much interchange of birds between the Mersey and the Dee (and to a lesser extent, the Ribble and Alt estuaries). I have compared changes on the Dee with the Mersey. Figure 1 shows that, although the Dee has shown a boom in recent years while the Mersey was decreasing, the Dee is also now falling and at the same rate as the Mersey. It may be that there is a wider issue with the Cheshire estuaries and it is just that the Mersey started to decline first.
Figure 1: Mersey and Dee Estuary bird numbers compared
You Can Help
The fact that is causing me most concern is that when I went on the count in October, I was 30 years younger than the next youngest person! There are 3 or 4 dedicated duck counters; some, like Graham Thomason, have been doing it since the 1960s while others have been doing it for a mere 20 years. The group in October were all over 70 years old and most have at least one of their joints replaced, but they still turn out each month! Looking back at the WeBS records recent counts on the Mersey are often in brackets which means an incomplete count. Therefore it could be that some of the decline is not an actual decline but a reflection of a lack of coverage. The existing team cannot cover such a big estuary and so we desperately need help. The lack of counters is not the main reason for the apparent decline in the Mersey but it is a concern, and without reliable and complete counts it is hard to assess the issue fully.
The Mersey estuary needs you! Despite the decline it is still an internationally important wetland and there are still spectacular numbers of birds, with over 30,000 Dunlin. Whooper Swans have been increasing recently and in amongst the Canada Geese that I saw in October was a Barnacle Goose and two Egyptian Geese. Birds of prey are common with Peregrine always present and Merlin seen on most winter counts. Hen Harriers sometimes winter on the Mersey estuary and the Frodsham Marsh Harriers also hunt the area. Little Egrets have increased and there is usually something out of the ordinary like Snow or Lapland Bunting, or Wheatear. I have even had a Redstart on passage. Some of you might remember Frodsham's 'purple patch' in 1999 when a Terek, and then Broad-billed Sandpiper turned up within a couple of weeks of each other. Where did they disappear off to? The Mersey estuary. So rarities do turn up and if you find one then you can have it to yourself as no one else will be able to get there until next month! What's more you can get closer to the wader flocks than you can on the Dee estuary.
We desperately need new birders. There is no public access to the south side of the estuary, except once a month when we go through Stanlow Oil Refinery and get the ferry across the Manchester Ship Canal. We then count all the waders in Manisty Bay, at Stanlow Point, in the River Gowy and at Ince and Frodsham Score. Although the winter counts are the most important there is a count each month. Counts in July and August in the late 1990s and early 2000s revealed a build up of up to 20,000 Shelducks making this the most important moulting site in Britain for this species.
If you want to come on any counts please ring Dermot Smith on 07505 418832 , or , or find the Mersey Estuary WeBS on the Facebook page. It is a big place and, although flat, walking to Frodsham Score is an 8-mile round trip so the counts usually take about 6 hours from meeting to departing.
Please put your birding to good use and help us to maintain coverage of one of Britain's best and most inaccessible wetlands.