Gros Banc and Orne dunes
In the absence of any replies, hopefully this info will be of use to anyone planning to a similar trip.
Visit dates: mid-April 2017
We were based in Asnelles, a couple of km east of Arromanches. Birding was incidental to a family holiday.
Common species in Asnelles - Linnet, Goldfinch, House Sparrow, Blackbird, Woodpigeon, Collared Dove, Robin, Starling, Chaffinch. Walking around the village during the week, we also saw Serin, Siskin, Chiffchaff, Black Redstart, Blackcap, and a number of other species more commonly encountered in the UK (Blue Tit, Magpie etc). Plenty of Swallows too.
Don't expect to find much on the beach - GBBG, Herring Gull, Pied Wagtail and not much else whilst we were there. The gulls and a few Cormorants use the remains of the Mulberry Harbours to roost, during the day at least.
The eastern edge of the village, north of the D514, is mainly holiday accommodation. Early in the season, so not many folks around, so plentiful and relatively undisturbed birds.
At the furthest eastern edge of the village, where the houses meet the beach, there's a footpath at the back of the dunes along the edge of extensive reed beds and pools between Asnelles and Ver-sur-Mer. Unfortunately the marshes appear to be private land - there's a vehicle track (marked as Chemin du Marais on Google Maps) but it's gated where it meets roads or footpaths - so I was limited to what I could see from the dune path. This included a pair of Marsh Harriers and Lapwing, so it's a pretty safe bet there's more to be seen here. Viewing also possible from the D514, which is to the south of the marshes and elevated, but a scope would be required.
More to follow on sites visited further afield.