September skies are alive with movement, as flocks of waders, waterfowl, and gulls transform London’s wetlands, reservoirs, and estuaries into staging grounds for migration. Starlings begin to swell in number, linnets chatter in large charms, and swallows and martins sweep southward in daylight, delighting watchers as they pass. Along the estuary, sandpipers, godwits, plovers, and redshanks gather in shifting groups, while ducks and geese arrive in impressive numbers—sometimes in the hundreds. Raptors like osprey and marsh harriers occasionally pass overhead, while rare visitors such as bluethroats, wrynecks, and Sabine’s gulls add unexpected excitement. Even terns can be seen diving or hawking insects as they continue their astonishing journeys. September offers no shortage of bird spectacles—you just need to know where to look.
Don’t miss these avian gatherings—return on September 7th to read more!
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Flocks of Waders, Waterfowl and Gulls
Seeing various different flocks of birds is another typical feature of the month. These may be just charming family parties of water rails at Barnes Wetlands or perhaps a roost of wagtails. Starling numbers are steadily increasing. Those seen earlier in the year may have already moved south or even west to Ireland. New arrivals are more likely to be coming from the north or possibly the east. Besides the impressive flocks of starlings there may be similar congregations of dunlin along the estuary. Other large flocks may include swifts, swallows, rooks and jackdaws. The most attractive and memorable flocks tend to be wagtails, yellowhammers, skylarks, linnets and goldfinches. The latter may even be moving in single-sexed charms. Some of these birds, when they flock, chatter excitedly to each other, particularly linnets which are capable of forming flocks of a hundred or more.
Swifts have already gone but swallows and martins, being such later breeders, tend to be in transit this month. Some of their young from earlier broods may have already set off. It is fortunate they choose to migrate in daylight as this allows us to see parties passing through places such as Beddington lakes. Here, flocks of a hundred or more sand martins are regularly recorded. Rarer smaller flocks or family parties can include mistle thrush, stock dove, stonechat, kingfisher and even blackbirds or tree sparrows. The latter also tend to favour the Beddington area. Away from it all on the sandy heaths north-east of London, red-legged partridges may have started to form small coveys. When a family is disturbed they all tend to run off rather than explode into flight.
The waders that chose to breed in the far, far north find that summer is so short they are already being forced to move south. Their advantage was that food was abundant and predation was low, but it can mean some leave having not even had time to moult. This means that while journeying south they may well stop off in London to feed and grow some new feathers before passing on. Twenty or more different waders may now be seen regularly along the estuary including sandpipers, godwits, plovers, greenshank as well as smaller birds such as sanderling, knot and perhaps even a wisp of snipe.
They are mainly in small discreet parties except for redshank and ringed plovers which can form more substantial flocks. As some of these birds are also in transition between summer and winter plumage they are often more difficult than usual to identify. Any problems are compounded by the presence of juveniles. Among the sandpipers it is the common sandpiper that is most likely to be seen but green, wood, pectoral and even curlew sandpipers can all make an appearance. There may also be sightings of curlew, whimbrel and little stint.
New ducks and geese have also started arriving. The largest numbers are usually tufted ducks with armies of five hundred or more appearing on lakes and reservoirs. They can look a ramshackle band as many are still in eclipse, as are many mallards. On some of our reservoirs shoveler, gadwall and wigeon can also reach good numbers but teal prefer to congregate along the river in quieter places such as Crossness and Barking reach. Rarer ducks such as gargeney, goldeneye and goosander occasionally make an appearance, as can scaup, scoter and long-tailed ducks in the open sea at the end of the estuary. Grebes such as great crested and the little grebe are also starting to turn up in unexpected places. There are the usual parties of greylag geese but now it is worth looking for individual bean or pink-footed geese among them and of course there are still the resident armies of Canada geese in London’s parks.
Among the raptors the occasional osprey, marsh and hen harrier fly over London in September and with luck a honey buzzard may be seen. Other great rarities recorded from time to time are ring ouzel, wryneck, ortolan bunting and spotted redshank. Even bluethroats are known to track down the east coast in September. There are also usually one or two rare gulls such as Mediterranean, little, yellow-legged, ring-billed, Caspian or Sabine’s as well as the more familiar kittiwake. One or two arctic and great skuas occasionally can also be seen passing by the end of the estuary.
Small flocks of terns drifting south along the coast diving together is another of the charming scenes associated with bird migration this month. Some decide to come through more central parts of London especially sandwich, black, little and arctic terns.
The arctic tern has one of the most astonishing migrations of any animal on the planet. Having nested within the arctic circle it is now on its way to spend winter within the Antarctic circle. These rare terns are usually seen as individuals. If close, the black tern can be recognised by its dark grey back, but from a distance it has a habit of hawking for insects over the surface of the water rather than diving in it, which can help give it away. However, it is the common tern that is more likely to be seen, especially around London’s reservoirs. They tend to dive or rather plunge into the water from a lower height than other terns and often at an angle. They are also seen hovering a lot.
