Water + mud + midges = birds

When we had those months of rain and wind last winter, the lagoons filled with more water than we had seen for years (see, for example, this post from 9 February). Actually, this was pretty good news, as it meant that the islands were surrounded in Spring, making it hard for mammals to get to the places the birds nest. We're still totting up our waterbird breeding counts (there are still young moorhens on the reserve), but we think it's been a fairly good year.

Now that Autumn migration is in full swing, we drop the water levels and keep on gradually dropping them, as the ideal is to expose fresh areas of wet mud suitable for feeding migrant waders each week. Not easy for us when we have no real water level control mechanisms, but the levels are looking great at the moment, and continuing to drop gradually. If you stand in the Coffee Shop, you might think that there's not a lot of water in the Shallow Lagoon, but walk a couple of hundred metres to the boardwalk and you'll find the right amount of water, lots of mud, and lots of waders!

Redshanks are most numerous, but look among them for greenshanks and knot that have been here this week. Small numbers of dunlins feed among them, and while we've been out on the mud this week, we can spot their feeding holes, like someone has been jabbing thousands of knitting needles into the lagoon. A green sandpiper was here on Tuesday (19th), a curlew sandpiper was reported on a couple of dates, and a few common sandpipers are still passing through (photo by Alun Williams on our Flickr page).

The great crested grebe chicks are now independent of their parents, and we think that one has now left the reserve, and we've been regularly seeing three little grebes on the Deep Lagoon. A female-type scaup was on the Deep Lagoon on Tuesday (12th), but was gone the following day.

The heavy rain showers brought lots of chiffchaffs, blackcaps and whitethroats into the bushes around the hides this morning (Friday 22nd), and we're still seeing reed and sedge warblers around the reserve. A swift yesterday (Thursday 21st) might be our last, however. A kingfisher has been spotted several times this week, including in front of the Coffee Shop. Let's hope it becomes a regular visitor through the winter.

We were out on the mud on Monday collecting core samples of mud from different parts of the lagoon. We do this each summer to check on how much food is available for our migrating waders. In particular, we count and measure chironomids, non-biting midge larvae, to calculate the density of tasty wader food. Densities are slightly lower than last year in the Shallow Lagoon and have increased in the Deep Lagoon, but our wetland ecology experts are happy that we've got reasonable levels in both.

Warden Sarah and volunteers Rosie and John were interviewed about this work for BBC Radio Wales Science Café, while Julian was interviewed about the monthly Wetland Bird Survey counts that help us monitor sites that are valuable to wetland birds across Britain. Listen out for it on Tuesday 26th August and Sunday 1st September, when the whole programme comes from the reserve.