The calls of the wild: Bob Jarman discusses the autumn migration of wading birds

Nature Notes: Bob Jarman discusses the autumn migration of wading birds

Waders can be difficult. There are many similar looking species, and opportunities to watch them away from the coast can be infrequent.

They usually feed on muddy margins, which can be temporary habitats. As saltwater or brackish water birds or freshwater feeders they often don’t give you much of a chance to identify them. One false move and they are gone. There is often one key identification feature though that gives them away: their flight call.

In the 1960s and early 1970s, snipe and redshank used to breed on the river meadows next to Fen Road in Cambridge. The hum of “drumming” snipe and the fluty calls of redshanks in their display flights were common sounds then, but the meadows have since been drained and heavily grazed.

Wader migration is intriguing. Birds passing through in spring are heading for the sub-arctic moorlands to breed in the very north of Scandinavia and Siberia. Six sanderlings feeding along the dam wall at Grafham Water on 27 May were probably heading north, but green sandpipers in mid-June, just two weeks later, had probably finished breeding and were heading south. The autumn wader migration often lasts into late October.

I have heard migrating green sandpipers, common sandpipers and whimbrels over Chesterton at night.

Jon Heath, the Cambridgeshire bird recorder, has taped the calls of many more wader species flying over on nocturnal migrations, including knot, turnstone and wood sandpiper. The birds are making use of the safer conditions at night, when fewer predators are active, navigating partly by the stars.

On their spring and autumn migrations, most green sandpipers are heading north or south to and from Scandinavia. There is a small breeding population of about nine pairs in Scotland making it one of the UK’s rarest breeding birds.

They nest in trees on a small platform of twigs! For a species of wader this is remarkable. Green sandpipers have a distinct call that clinches identification – usually a clear whistled “tooleet tooleet”.

Common sandpipers occur along the margins of the River Cam in the city on both migrations. They too have a distinct flight call, a high pitched “swee zee zee” and a strange flickering flight, low over the water.

Whimbrels are curlew-like waders that breed on the moorlands of Shetland and the Hebrides and have been seen over Trumpington Meadows and Chesterton; a flock of 43 over Little Shelford one August probably passed over the city. Their call is unmistakable, a clear six to eight note whistle: “pee pee pee..…….. pee”!

Dotterels are now rare and declining plovers and can occur in spring and autumn. A small population nest on the bare scree mountain tops in Scotland. They can be very tame. In the 18th-century large numbers were shot in spring near Balsham and Fulbourn for the upmarket restaurant trade in London. Their name comes from “dotard”, meaning idiot, because they were so easy to shoot!

For birdwatchers, finding and identifying rare species of waders is a challenge. Up to the mid-1960s Cambridge Sewage Farm – “this evil smelling bird paradise” – was one of the best places in the country for rare waders.

I remember learning the calls of wood sandpipers and Temminck’s stints there. I recall that the settling ponds were surrounded by tomato plants and then later chilli plants as Asian restaurants became established in the city! The seeds clearly passed through bodies and the sewage unharmed.

The pectoral sandpiper is becoming an annual autumn rarity in Cambridgeshire. It breeds in Alaska and north-east Siberia and winters in South America. In the USA it is an uncommon bird on migration. Its breeding range could be expanding into western Siberia and these birds may have established westerly migration routes to new wintering grounds.

A particularly confiding pectoral sandpiper spent nearly a month at Dernford Reservoir near Great Shelford – maybe it had not encountered humans before?

I used to work at the National Institute of Agricultural Botany (NIAB). There was a small field margin that was always wet. Every year precisely on 23 or 24 June (never earlier, never later!) a flock of juvenile lapwings would arrive and spend a week feeding and resting there. It was as though that precise spot was a traditional stopping-off point on their autumn migration. Eventually this margin dried, was planted with saplings and the lapwings never returned.