multi-colored duck, early 14c. (late 12c. as a surname), from sheld- "variegated" + drake "male duck." The first element probably is cognate with, or from, Middle Dutch schillede "separated, variegated," West Flemish schilde, from schillen (Dutch verschillen "to make different"), from Proto-Germanic *skeli-, from PIE root *skel- (1) "to cut."
This is the origin considered most likely, though English sheld by itself is a dialect word attested only from c. 1500. OED finds derivation from shield (n.), on resemblance to the patterns on shields, "improbable." Compare sheldapple, a 16c. name for types of birds remarkable for variegated plumage (the second element of that might be a variant of alp, an old word for "bullfinch").
updated on August 21, 2022