The Wetland Bird Survey Report - Waterbirds in the UK 2010/11 - has
recently been published. It can be read online on the BTO website,
The WeBS report always gives us an opportunity to see how the nation's wetland birds are doing and how numbers on the Dee Estuary are changing relative to sites elsewhere in the country. In this article I'm selecting four species in the first half of the Report (Wildfowl/ Divers/ Grebes/Herons) to go into more details and discuss trends, followed by an article next month discussing four species from the second half of the Report (Waders/Gulls/Terns). To clarify, the WeBS 'year' goes from July to June.
In 2010/11 the Dee Estuary had the highest count in the country with 12,234 during October. This was more than twice the next highest count which was 6,081 at Morecambe Bay, a much larger area. Compare that count for the whole of Morecambe Bay with the 8,100 we had on Thurstaston Shore in October 2010, an amazing sight with Dawpool Bank just covered with the birds. There have only ever been three counts higher than 12,234 on the Dee Estuary, in 2003 and 2004 with the max 13,334 in October 2004. We know that since 1995 many Shelduck moult on the nearby Mersey Estuary during July and August rather than flying to the traditional moult site on the Waddensee, more recently it seems likely that some birds have also been moulting on the Dee Estuary. Moulting locally means that numbers build rapidly here during the autumn in contrast to most sites around the country which peak during the winter as birds find their way back from Holland.
Cormorant numbers just keep on increasing on the Dee Estuary. This is in contrast to the national trend where counts have been fairly stable over the past 10 years. Over the past three winters (08/09 to 10/11) counts on the Dee Estuary have even exceeded that from Loughs Neagh and Beg in Northern Ireland and the five year average of 1,204 means we now qualify as a site of International Importance for this species.
The nearby Alt Estuary usually has similar numbers to the Dee Estuary and in 2010/11 had the largest count with 1,459, almost double the previous winter and the highest ever recorded there. I was amused by the comment in the Report that 'given the proximity of the sites, there may be some degree of exchange of Cormorants between the Dee and Alt Estuaries'. Anybody who bird watches along the north Wirral coast will know this is undoubtedly true with a constant stream of birds flying back and forth between the two sites - something of a distraction when we are looking for rare and exciting sea birds! The WeBS counts, which take place at high tide, don't necessarily record the highest numbers. The largest count ever recorded on the Dee Estuary was a remarkable 2,478 seen from Hilbre on Nov 24th 2009 when almost 1,700 flew out of the estuary at dawn whilst 800 were already on East Hoyle Bank.
Looking back now it seems amazing that it was such a short a time ago as 1996 that Little Egrets were first recorded breeding in this country, and that the maximum counted for WeBS that year was only 502. After 1996 there was a massive increase in numbers so that by 2007 the max WeBS national count had reached 3,900 after which numbers have increased more slowly with 4,423 in 2010/11.
This increase took place almost wholly along the south coast of England and Wales with three noticeable exceptions - The Wash, Lavan Sands (just east of Bangor in North Wales) and the Dee Estuary. On the Dee Estuary there was little increase in numbers until 2001 when there was a count of 18 compared to just six the previous year. The graph above neatly demonstrates that numbers then started to increase at a much faster rate than most of the other sites and by 2005/06 the Dee Estuary was the seventh most important site with a count of 112 and by 2010/11 we are now the third most important site in the country with a count of 303. Birds breed at Burton producing around 80 young a year, and colour ringing has shown we also get many young flying here from the colony at Penrhyn (near Lavan Sands), so it is hardly surprising that numbers continue to increase here. Incidentally, numbers on the Wash (a much larger area than the Dee Estuary, of course), increased from just five in 2000/01 to 543 in 2010/11, making it the most important site in the country.
It was only in 2006 that it was
realised that there was a resident flock of several hundred Great
Crested Grebes off North Wirral and regular counts started.
Consequently counts for the Dee Estuary WeBS area have increased from
just 33 in 2005/06 to a
remarkable 1,195 in 2010/11. That latter count was the second
highest in the country. The five year mean stands at 584 but this will
increase as we had a count over 800 last winter and already a
count over 900 this winter. For more
details about the North Wirral Great Crested Grebes see the December 2010 Newsletter.
WeBS (Wetland Bird Survey) data in this article should not be used elsewhere in any way without permission of the WeBS Office. To access official WeBS data please contact the WeBS Secretariat - BTO, The Nunnery, Thetford, Norfolk IP 24 2 PU www.bto.org.
Please note that BTO are
currently looking for WeBS counters for the Mersey Estuary.
If you are
interested please contact them, details on:
14th December, 11.22hrs (GMT), 9.9m.
15th December, 12.11hrs (GMT), 10.0m.
16th December, 12.59hrs (GMT), 9.9m.
Organised by the Wirral
Ranger Service , Flintshire Countryside Service and/or the
All these events and walks have bird interest, even those not advertised specifically for birdwatching. No need to book for these events unless specified - please check below.
Also see 2012 Events Diary.