Pratt, H. M.
Breeding attempts by juvenile Great Blue Herons. Although most North American herons probably do not attempt to breed for the first time until the breeding season of their second year, records of breeding by Black-crowned Night Herons (Nycticorax nycticorax) (Gross 1923), Green Herons (Butorides virescens) (Meyerriecks, in Palmer 1962), and Little Blue Herons (Florida caerulea)( Palmer 1962) in juvenile plumage indicate that in these species a few individuals attempt breeding at about 1 year of age. Owen (1959) reported breeding that he considered exceptional by yearling Grey Herons (Ardea cinerea) in Great Britain. Millstein et al. (1970) found breeding attempts by yearling Grey Herons to be common at the Willoughby Wood heronry in England in 1967. The Cattle Egret (Bubulcus ibis) also sometimes breeds at the age of 1 year (Palmer 1962).
Pratt, H. M. 1973. Breeding attempts by juvenile Great Blue Herons. Auk 90: 897-899.