Great Spotted Woodpecker
Dendrocopos major

This striking bird can be seen anywhere along the trail where there are trees but most often around Old Castle Road (section 4) and the Marsh Road Embankment (section 2).

The call is very distinctive too - a loud, sharp "peek-peek".

In spring they also make a drumming sound on hollow branches, but only if they are setting up a territory in an area where there is competition from others - I've not heard this yet from the trail.