I did the monthly bird count on the 4th. There was still quite a lot of singing by resident species, if less than last month and the resident Great Spotted Woodpeckers were silent, presumably busy at the nest. This casts some doubt on the April start for the Birds in Greenspaces scheme, perhaps not optimal for those residents. A Nuthatch was singing in Ashen Grove Wood, so the mismanagement by AELTC must have left some veteran features. The Grey Wagtails were seen on the upper Brook, as usual, and doubtless were breeding somewhere there. The Grebes were still present, so there must have been a few fish to feed upon. I saw three male Pochards on the first of the month, but they were gone on my later visits. The Mute swans are now just the pair, with the Pen sitting on a nest on the Wimbledon Club lake shore. Bare patches in the Great Field had been repaired and there were some 30 Feral pigeons enjoying the free grass seed. Let's hope that the seed isn't chemically treated.
On the 12th I did a bird spotting walk for the national Birds in Greenspaces scheme. A highlight was a sighting of Nuthatch hunting insects on the trunk of a small tree in the public park section of Ashen Grove Wood and watching the Stock Doves and Jackdaws contesting nest sites in the dead veteran Ash tree beside the lake outfall structure. A sad note was a huddled, ill female blackbird, doubtless suffering from the fatal Usutu virus, which is transmitted by Culex mosquitoes. The recent onset of the disease might be symptomatic of climate change causing the invasion of southern species of mosquito, with the accompanying disease risk. Fortunately, Usutu is not known to cause mortality in other other species, or us!
I did the lake water sampling in the 13th, finding that both nitrates and phosphates were then below the pollution threshold. However, the bad news was that the cyanophyte (Blue-green "alga"), Oscillatoria, was abundant across the whole lake bed, combining with the upper layers of sediment to make a slimy goo. Some floated to the top, buoyed up by trapped oxygen, but that was a tiny proportion of the what remained on the bottom. I presume it was the Oscillatoria that had soaked up the nutrient pollutants. We are lucky that it seems not to be toxic (yet), but it leaves the lake water in a dreadful state. There were a few scraps of Rigid Hornwort, a floating waterweed. Lets' hope that it thrives and shades out the cyanophyte. Meanwhile, I look on as dogs are encouraged into the water and children have great fun splashing in their canoes, glad that the precautionary advice to treat the weed as toxic hasn't proved itself. Water clarity remained good, as I could still see my Secchi disk at 1.5m depth off the end of the, now extended, watersports jetty. This would be because there were still plenty of water fleas filter-feeding on the microscopic algae. Over the winter it was mainly the common water flea and the great water flea, but the long-spined flea is now showing up too and a fourth, bottom-dwelling, species.
At the beginning of the month both the Blackthorns and the Hawthorns were beginning to break their leaf buds, but the Blackthorns were in full flower and nothing yet showing on the Hawthorns. The Wild cherries were in flower in Horse Close Wood, so were readily found. They blend in with the surrounding trees once the flowers drop. There is an abundance of flowers on the Green Alkanet, which is all too successful around the edges of the park.
In the Spring large groups of nursery school toddlers are enjoying the park, which is great to see. An array of logs has been moved into the Lofthouse Glade for outdoor classroom seating, used informally by others too. It's great to see Horse Close Wood so used and the wildflowers appreciated. Let's hope that all the activity is naturally-based, we don't enjoy plastic glitter in this natural scene.
