155816 Great Northern Diver Gavia immer L 75-85cm. Buoyant waterbird. Large bill is held level or very slightly elevated. Sexes are similar. Adult in summer has black neck with two rows of white stripes. Upperparts are blackish with white patches on mantle and spots elsewhere. Underparts are gleaming white. Bill is dark. In winter, has dark grey upperparts and whitish underparts with dark half collar on neck. Bill is greyish. Juvenile is similar to winter adult but slightly grubby-looking. Voice Silent in our region. Status Non-breeding visitor to coastal seas, favouring both rocky shores and large bay; occasional on inland reservoirs.