|Snowy Egret, Egretta thula. Note the chicks in the nest.|
About 17, see text
On the other hand, egrets are not a biologically distinct group, and are called egrets because they are mainly white and/or have decorative plumes. Although egrets have the same build as the larger herons, they tend to be smaller.
The classification of the individual heron/egret species is fraught with difficulty, and there is still no clear consensus about the correct placement of many species into either of the two major genera, Ardea and Egretta.
Although herons resemble birds in some other families, such as the storks, ibises and spoonbills, they differ from these in flying with their necks retracted, not outstretched. They are also one of the bird groups that have 'powder down'.
- Martínez-Vilalta, Albert; Motis, Anna 1992. "Family Ardeidae (Herons)" in del Hoyo, Josep; Elliott, Andrew; Sargatal, Jordi: Handbook of the Birds of the World. Volume 1, Ostriches to Ducks. Barcelona: Lynx Editions. pp376–403 ISBN 978-84-87334-10-8