Dave Dawson’s natural history notes for 19th April 2018:-

Just one Black-headed gull left, so they have departed for their breeding areas. The importance of Ashen Grove Wood is shown by birds singing there and doubtless breeding: Blackcap, Blackbird, Blue tit, Chaffinch, Dunnock, Great tit, Mistle thrush, Robin, Song thrush, Wood pigeon, Wren and Stock dove. The Wood millet is beginning to flower in Ashen Grove Wood. Just 14 Canada geese seen, but April has the lowest counts as most depart to breed elsewhere. The 31 Coots were the second highest April count, suggesting that waterweed in the lake has served them well, but the 22 Mute swans were 1/3rd of the number back in 2015, so they continue to decline. Both these species were building nests. Two Shovellers on the lake were unusually late: they have usually departed to breed elsewhere by April. The 49 Tufted ducks were the highest April count in the last 30 years: this continues a long-term increase. There were 9 Egyptian geese on the area of damaged grass where the Christmas trees were on sale: inspection shows a vigorous growth of weed seedlings, especially knotgrass. They were there again a week later when I went past. It looks as if these weeds are a tasty bite. I saw no Swallows nor martins, but have seen Swallows feeding over the lake on other visits this month. Doubtless these are on migration. The nearest place they breed is at the Windmill on the common. When doing field work on The Wimbledon Club lakeside I saw a Common sandpiper, doubtless also on migration, and two Grey wagtails. This is the first time I’ve seen the wagtails in April, I see most in the autumn, again probably on migration, but I see them occasionally at the stilling pond in Ashen Grove Wood and on the brook in the public park throughout the year. In the lake there were huge numbers of waterfleas (Daphnia, probably curvirostris or longispina), but by the 25th these had died off and the water surface had millions of floating, resting-stage eggs. The Sweet violet flowering was over. Trees were leafing up, and flowers were prominent on the Ash trees. Other flowers included White deadnettle, Cow parsley and Green alkanet.