Whimbrel (Numenius phaeopus)
Poole Harbour is a favoured place for these birds, along with Christchurch Harbour and the Fleet.
The problem with Whimbrel is that they can be really difficult to tell from a Curlew and sometimes it helps to see both together. I wonder how many of us have dismissed a Whimbrel as 'just another Curlew'?
The key really is the bill; long and down turned like a Curlew, but no where near as long. It also seems to bend at a point two-thirds down whereas the Curlew's bill is a more gentle curve.
The Whimbrel is also a less bulky bird, more compact perhaps? The markings on the head differ but unless you have a really good view that can be difficult to tell from a distance.