In cockyolly bird, a nursery or pet expression for dear little bird: cf. Dicky-bird.
1837. Correspondent says, Cockyolly bird was familiar to me as a schoolboy in 1837.
1857. Kingsley, Two Y. Ago, xv. So Major Campbell prepares the charming little cockyoly birds. Ibid. (1863), Water-bab., viii. 310. All the butterflies and cockyoly birds would fly past me.
1877. Besant & Rice, Son of Vulc., I. xi. 118. The little cockyolly bird is taken in the net.