means To strike or pick at something with a beak or a quick, sharp point — or, as a noun, a unit of dry volume equal to a quarter of a bushel (about eight quarts).

from Two pecks share the page but not necessarily the same nest. The bird's peck is Middle English 'pecken,' a cousin of 'pick' and likely echoing the sound and motion of a beak tapping — much of Germanic bird-vocabulary works this way, by imitation. The measuring peck is Middle English 'pek,' of murkier descent: possibly borrowed through Anglo-French, though its ultimate root is honestly uncertain. Whether the two were ever the same word, nobody can say for sure — but it's a tidy coincidence that both involve taking things in small, sharp amounts.