Decline, Sand Eel, Day, Common Guillemot, Alcidae, Theft, greater sandeels, Parent, Uria aalge, Adaptation, Food, Outside, Guillemots, Nature, Piggy back, Breeding Birds, Environment, Sea Bird, Mass, Onlookers, Breeding Colony, Behaviour, Watched, Coastal habitat, Farne Island, Robbery, Auks, Birds, Animal, Daylight, Many, Adult, Hyperoplus Gymnammodytes, The Gillemots, Bird, Adult Animal, Parents, Vertebrate, Common Murre, Outdoor, Flock, Fishing, Colony, Bystanders, Northumberland, Aves, Pressure, On top, Farne Islands, Mugged, Sea Birds, Landed, Black And White