September is a month of change, with the last vestiges of summer breeding giving way to the arrival of wintering birds. Waders, such as redshanks, ringed plovers, ruffs, common and green sandpipers, move through the Pits complex in small numbers, though only the latter are likely to stay for the winter. Look for waders on Washout Pit, to the north of the Heronry Lake.
The breeding season just about hangs on into September, with some pairs of great crested grebes still behaving as though it is spring – even displaying on some of the more sheltered lakes, such as Heronry North and South. Some will still have well-grown young with them, maintaining the bond until well into autumn. Family groups of breeding ducks, such as gadwall and tufted duck, have now split, being joined by birds from elsewhere. Some young grey herons and cormorants stay in the area into September, though will disperse as we head towards winter.
Increasingly, we seem to have many more swallows and house martins through during September than were seen around during the breeding season. Keep an ear open for hundreds at a time, busily feeding ahead of their long flight to Africa. Sometimes, over 1000 swallows fly around together on a single evening in early September – where do they roost?
Resident species, such as tits and finches, are feeding in flocks in scrub around the Meadow and Heronry Trail footpaths, joined by the last of the passage warblers until mid September. Hobbies can remain in the area throughout September, while other less common raptors, such as ospreys and marsh harriers, can make a chance appearance during the month. It can also be a good month for brief visits from little gulls, black terns and the scarcer grebes.
By the end of the month, the birds around the Pits are mostly comprised of those that will be around for the next few months: wigeons, pochards, tufted ducks, shovelers and teal. Both of the Heronry Lakes and Island Pit are good bets for these wintering wildfowl, but surely this is the winter when we’ll find a ferruginous duck or lesser scaup among them?
Meanwhile, as the leaves change colour and start to fall, it becomes easier to see the many galls which have been developing all summer. Look for knopper gall, marble gall and spangle gall on English oak trees, all of which are created by gall wasps. The Camellia gall is common on white and crack willows – look for a rosette of leaves at the tips of shoots. There are also several galls on willows, such as bean gall and spherical leaf gall which are caused by gall gnats. Although the sycamore is not always noted for supporting a great variety of species, it does have galls, which are caused by mites such as the red pustulate gall.
Paxton Pits has a large variety of berry-bearing shrubs: as well as the familiar rose, hawthorn and bramble, you can see common buckthorn, spindle, elder, blackthorn, white and black bryony, woody nightshade, dogwood, ivy and dewberry. The berries are ripening now and should provide an important food source for late insects and migrant birds.