Treskilling Downs near Luxulyan is bisected by one of the clay trails and is a mixture of downland, woodland and fishing lakes. No sign of the Sand Martins in the face of the clay tip but a good birding walk. We heard or saw, amongst others, Blackcap, Chiffchaff, Willow Warbler, Garden Warbler, Mistle Thrush, Yellow Hammer, Linnet, Buzzard, Kestrel.
Some images are below including a Sparrowhawk on my garden wall.

Juvenile Mistle Thrush

Female Yellowhammer

Sparrowhawk