I have been recording the birds on the Bayfield estate since 1997 and my survey patch includes beautiful Bayfield Lake.
In summer-autumn 2012 Bayfield was de-silted in a major project aimed at improving the ecological quality of the lake – see the blog post entitled “The secret history of Bayfield lake” for more details. It has been said that waterbird populations are a key indicator of the health of a lake, so my observations on changing bird populations may well become very meaningful when it comes to understanding how the lake is faring over the next few years.
Over 2007-2012, prior to the mud-pumping, I noticed a major decline in waterfowl broods which I thought might be due to the silting up of the lake and a decline in invertebrate and plant food. Indeed, by 2012, mute swan was the only species to raise any young.
Mud pumping started at the end of June 2012 and continued to the end of October. The lake almost completely drained towards the end of this period leaving only mud and a few muddy pools. Grey heron (5) and little egret (2) then helped themselves to trapped fish.
At the end of December, despite being isolated from the river, the lake magically filled to near capacity by seepage from the water meadows. Then it all started to happen – mallard, teal, tufted duck and even a pair of shoveller took up occupation – truly remarkable! What did the tufted duck feed on I wonder? They dive to graze off aquatic vegetation (and associated invertebrates) but no plants were visible. Answers on a postcard!
Over the last few months I have been observing the birds on a regular basis and things continue to look good. Today (2nd April) I saw a male pochard, some shoveller, 25 teal, 4 tufted duck (although there have been up to 8 recently), 20 or so mallard, 16 gadwall, numbers of moorhen (although no coot as yet) and a pair each of canada and greylag geese. The lake is becoming a waterbird-friendly place again and I have not seen it this good since the late 1990s. To top it off there were 6 magnificent curlew in the lakeside meadows.
All the signs are there that the lake is coming back to us and I will get out afloat when the weather warms up to try and work out what the birds are feeding on with Carl Sayer. Watch this space for an update soon.
Len Bentley