Sentence:  "The people at home call it a rook's <WSD>parliament</WSD> when a whole crowd of rooks settle on some bare, wide common, and sit there as if they were consulting, not feeding, only stalking about with drooping wings, and solemn black cloaks." 
Meaning of the word marked with <WSD> tags:  A gathering of birds, especially rooks or owls. (from 15th c.)