E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Dotterel
or Dottrel. A doting old fool; an old man easily cajoled. The bird thus called, a species of plover, is said to be so fond of imitation that any one who excites its curiosity by strange antics may catch it.
1
To dor the dotterel. Dor is an archaic word meaning to trick or cheat. Whence the phrase to dor the dotterel means to cheat the simpleton.