The order Pelecaniformes contains several medium to large waterbirds. Currently, it includes the following families: Pelicans (Pelecanidae), Ibises and Spoonbills (Threskiornithidae), Herons, Egrets and Bitterns (Ardeidae), the Shoebill (Balaenicipitidae), and the Hamerkop (Scopidae).
In Japan, the intergeneric hybridization event between a male Little Egret (E. garzetta) and a female Chinese Pond Heron (Ardeola bacchus) was recorded and described (Mashiko et al., 2012).
In South Dakota, the interbreeding of a Tricolored Heron (E. tricolor) and a Snowy Egret (E. thula) was reported (Meeks et al., 1996). More reports on hybrid herons can be found in the references of these papers, for instance Sprunt (1954).
Several sightings of dark morphs of Little Egret in India might actually be hybrids with Indian Reef Heron (E. schistacea)(Koparde & Yesou, 2017).
A study that set out to investigate whether the Mauritanian Spoonbill (Platalea leucordia balsaci) is a valid subspecies detected introgression from another subspecies, the Eurasian Spoonbill (P. l. leucordia), into P. l. balsaci (Piersma et al., 2012).
Interspecific hybridization of spoonbills has been observed in captivity and nature. The international Zoo Yearbook of 1984, for instance, reports hybridization between a Roseate (Platalea ajaja) and a Eurasian (P. leucorodia) Spoonbill and between an African (P. alba) and a Eurasian Spoonbill.
In South Korea, researchers observed natural hybridization between Black-faced Spoonbill (P. minor) and Eurasian Spoonbill (Kwon et al., 2017).
In the state of New South Wales, Callaghan et al. (2017) observed a possible hybrid between Australian White Ibis (Threskiornis moluccus) and Straw-necked Ibis (T. spinicollis). The plumage of this bird showed characteristics of both putative parental species. It is not the first time that this particular hybrid has been reported. In 1983, Disher described a similar bird, although he also considered the possibility that it was a bird with aberrant plumage. So, to be absolutely sure about the identity of this peculiar bird DNA analysis is probably necessary.
Callaghan C., Ryall S. & Kingsford R. (2017) A probable Australian White Ibis Threskiornis moluccus× Straw-necked Ibis T. spinicollis hybrid. Australian Field Ornithology 34, 47-48.
Disher, P. (1983). An unusual ibis. Bird Observer 620, 77.
Koparde, P & Yesou, P (2017) Probable hybrids Little Egret x Indian Reef Heron in India and Sri Lanka. Dutch Birding 39, 238-246.
Kwon, I.-K., Lee, K.-S., Lee, J.-Y., Park, J.-H. & Yoo, J.-C. (2017). Hybridization between the Black-Faced Spoonbill (Platalea minor) and Eurasian Spoonbill (Platalea leucorodia) in South Korea. Waterbirds 40, 77-81.
Mashiko, M., Fujioka, M., Moriya, K., Hagimoto, T., Yamaguchi, M. & Toquenaga, Y. (2012). Natural Hybridization between a Little Egret (Egretta garzetta) and a Chinese Pond Heron (Ardeola bacchus) in Japan. Waterbirds 35, 160-163.
Meeks, W. A., Naugle, D. E., Johnson, R. R. & Higgins, K. F. (1996). Interbreeding of a tricolored heron and a Snowy Egret in South Dakota. Auk 113, 955-957.
Piersma, T., van der Velde, M., El-Hacen, E. M., Lok, T. & Overdijk, O. (2012). Molecular verification of the subspecies status of the Mauritanian Spoonbill Platalea leucorodia balsaci. Ardea 100, 131-136.
Sprunt, A. (1954). A hybrid between the Little Blue Heron and the Snowy Egret. The Auk, 314-314.