Like all birds dependent on freshwater and marine wetlands, members of the heron family are suffering progressive loss of essential habitat. In addition, agricultural and industrial pollution threatens their capacity to reproduce.

Marin County California heron colonies: 1967-1981

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.

Breeding attempts by juvenile Great Blue Herons

Information available in the ornithological literature about breeding biology of the Great Blue Heron (Ardea herodius) and the Common Egret (Casmerodius albus) is fragmentary at best. Breeding behavior preceding and during pair formation of the Great Blue Heron has been described by Bent (1926), Cottrille and Cottrille (1958), and Meyerriecks (1960). Miller (1943) comments on some aspects of breeding biology of the Great Blue Heron in the Philadelphia region but his data suffer from lack of quantification.

Breeding biology of Great Blue Herons and Common Egrets in Central California

A case of intra-specific infanticide is recorded in the Great Egret (Ardea alba) and two cases of inter-nest infanticide are reported for the Black-crowned Night Heron (Nycticorax nycticorax).

Inter-nest infanticide in ardeids