Slightly smaller than a Blackbird, in all plumages, it appears very compact and dumpy. It is a widespread resident along rocky streams and rivers. Habitually bobs up and down when perched. Flies low over the water. Adults are reddish-brown with a large "bib" of white on the throat and breast. Also has a broad rusty brown patch where the white bib ends on the breast. Juvenile Dippers have the brown plumage tones replaced with grey and the white bib reduced to a small area on the throat. The underparts are barred grey, while at close range, a small white eyering can be seen.
Source: https://www.birdwatchireland.ie/IrelandsBirds/Dipper/tabid/1134/Default.aspx