As promised here is the second article
about The Wetland Bird Survey Report -
Waterbirds in the UK 2010/11 - which has
recently been published. The Report can be read online on the BTO
This month I'm going into details about four species found in the second half of the Report. The first article, which was about Shelduck, Cormorant, Little Egret and Great Crested Grebe, can be read here.
The max WeBS count of Knot on the Dee Estuary in 2010/11 was 20,572, this was in December during exceptionally cold weather. The count was well above the five year mean of 15,207 but very close to the long term average for the past 30 years. Knot numbers vary widely from year to year for various reasons, for example in 2000/01 the max count was only 5,672, whereas the following winter they reached a massive 52,762! The reasons for these large swings are discussed in my WeBS and Waders article, with one of the main factors being the height of the tide. On the highest tides the roosts at Point of Ayr, Hoylake and West Kirby are covered by the sea so the Knot have to fly to the next available roost site which is the Alt Estuary (and adjacent Formby shore) and are therefore 'lost' to the Dee Estuary WeBS counts. January 2011 was a good example of this, the WeBS count day coincided with, for January, an exceptional high tide of 9.9m and as a consequence the Dee Estuary count dropped from 20,572 in December, on a 9.2m tide, to just 522 the following month. In contrast the January count on the same day at the Alt Estuary was 48,301, one of the highest ever counts there, although that Alt count will have included birds from the Ribble Estuary where numbers were also low.
Another reason why Knots move away from the Dee Estuary at high tide is disturbance, even in winter a nice sunny day can result in a lot of people down on Hoylake Beach, their main roost. Voluntary Wardens do try and reduce this disturbance but need all the help they can get, if you are interested see the Dee Estuary Voluntary Wardens web page.
Like Knots the max WeBS counts for Dunlin on the Dee Estuary swing widely from year to year, but the five year moving average showed a steady increase from 1989/90 until 2003/04 when there was a max count of 41,679, the highest since 1977. Since 2003/04 there has been a sharp decline with the five year moving average halving so it now stands at just 15,921. Nationally there has also been a decline, thought to be due to birds short-stopping on the Waddenzee with the run of mild winters. As you would expect the cold winters of 2009/10 and 2010/11 saw a rise in numbers nationally but surprisingly the max count on the Dee Estuary in 2009/10 was very low at 9,654. However, numbers recovered in 2010/11 such that the count of 18,574 was the highest since 2005/06.
A footnote: when I wrote my article on North-west Estuaries I commented that 'The count for the Mersey Estuary for 2008/09 was very low but hopefully was just a one off poor winter'. Thankfully that was indeed the case and max counts since then were 44,030 (09/10) and 41,430 (10/11) confirming the Mersey Estuary as the most important site in the country for Dunlin.
In 2010/11 the Dee Estuary had the second highest count in the country with a max of 6,188, one of the highest ever counts here. Numbers on the Wash are always the highest with counts of around 10,000 whereas the Dee Estuary, Ribble Estuary, Humber Estuary and Thames Estuary all have similar numbers of birds, usually between 4,000 and 6,000. Colour ringing shows there is much interchange between these sites through the year, in particular between the Dee and Ribble with Marshside RSPB on the latter site often holding several thousand birds.
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:
12th January, 11.13hrs (GMT), 9.8m.
13th January, 12.00hrs (GMT), 10.0m.
14th January, 12.45hrs (GMT), 10.0m.
15th January, 13.28hrs (GMT), 9.8m.
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.