Grasshopper warbler is noteworthy visitor

One of the most elusive of the returnees, the grasshopper warbler, is starting to be heard again in its summer haunts, the males delivering their strange song which is compared to the sound of an angler winding in a reel, a faint bell in an alarm clock or, of course, a grasshopper.

They are small inconspicuous birds with streaky olive-brown plumage and for much of the summer are hard to see. But over the next few weeks the males are delivering this reeling song, which goes on and on, from the top of a bush, post, or reedbed to attract a female.

The sound seems to be rising or falling because the singer is frequently turning his head from side to side. The song is so high-pitched that older people often find itimpossible to hear.

It has also been estimated that the song contains 1,400 double notes a minute and a male that sings throughout the night, as they sometimes do, might deliver as many as 250,000 notes in a single session.

Once the male has successfully paired up, he continues to sing for a while but from deeper in the undergrowth.

Grasshopper warblers were once thought to be only found at the edges of marshland and places such as the Blacktoft Sands and Fairburn Ings reserves are still the best places to listen for them. But they are also to be found in drier places where there is plenty of low vegetation for them to skulk under and look for food without coming out into the open.

Numbers vary from year to year, depending on how they have fared on their wintering grounds in Africa – last year there seemed to be fewer around the region.

Common cranes have been seen in a number of places with two circling Astley Lake, Swillington Ings for 10 minutes on Friday last week and presumably the same two seen later over the Nosterfield reserve in North Yorkshire. They were seen over Nosterfield again on Sunday and over the Old Moor reserve and Wintersett reservoir. On Saturday, three were over Driffield and the nearby Tophill Low reserve – two ospreys were also present there.

The immature white-tailed eagle, a bird released in August 2008 as part of the Scottish reintroduction programme, was seen again, this time on Saturday from the Barden Tower raptor viewpoint near Bolton Abbey.

At the Blacktoft Sands reserve, there are at least 20 marsh harriers nest building and displaying, some in front of the visitor centre and around 100 black-tailed godwits. The first sedge warblers are also back.

A grey-headed wagtail, one of the many European forms of yellow wagtail, was seen at Fairburn Ings, a third record for the reserve.

Along the east coast, a black redstart was seen at the Crown and Anchor, Kilnsea and a firecrest near South Landing at Flamborough.

Further north, a drake blue-winged teal has returned for the second year to the

RSPB's Saltholme Pools reserve on Teesside.