On less visited coastlines (and occasionally inland), a shrill kipeep! can be heard and if you can find the source, then you should see an Oystercatcher. They are a very distinctive black and white with a large, bright orange-red bill that they use to probe for worms and molluscs. These two were on Cumbrae, an island which is good for photographing seabirds.
1: Cumbrae, 23/04/2005.
2: Cumbrae, 04/06/2005.