Oystercatchers are in their own family, the Haematopodidae which I believe means blood-footed. Like other oystercatchers the adult's distinctive bright red bills are used like a knife to shuck bivalves, but oystercatchers are also reported to swallow whole limpets and regurgitate the shells in the form of pellets. Females have a longer bill than males. Three subspecies normally recognized. Iceland birds belong to the widespread nominate race. The bird with the dark bill tip is an immature. HBW lumps this species with the South Island Oystercatcher Haematopus finschi of New Zealand which has less black on its back.
Canon SX50 HS PowerShot.
References:
Chandler, R. (2009). Shorebirds of North America, Europe, and Asia: A photographic guide. Princeton.
Hockey, P., Kirwan, G.M. & Boesman, P. (2018). Eurasian Oystercatcher (Haematopus ostralegus). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from https://www.hbw.com/node/53753 on 9 October 2018).