Domain: Eukarya
Kingdom: Animalia
Phylum: Chordate
Class: Aves
Order: Pelecaniformes
Family: Ardeidae
Genus: Nyctanassa
Nyctanassa violacea


Figure 1.1. This phylogenic tree displays relationships between different herons in the Ardeiae family. The yellow-

                 crowned night heron form their own apomorphic branch and are most closely related to Nycticorax and

                 Butorides (Sheldon et al. 2000).

The yellow-crowned night heron belongs to the domain Eukarya, or organisms with cells containing a nucleus and membrane bound organelles. Further down we see they fall in the kingdom Animalia, because of their multicellularity, lack of cell walls and mobility. Further into the animal kingdom we see they belong to the phylum Chordate, because they have organized tissues, are triploblastic, deutersomes, and possess a notochord. In the yellow-crowned night heron this is seen as a vertebrae made of bone or osseous tissue.

Night herons belong to the class Aves (or clade Avialae) meaning they are feathered, winged, two-legged, warm blooded and lay hard shelled eggs. This is what we would typically think of as a "bird" (Van Tuinen 2009; Hackett et al. 2008). Other species in this class include the Harpy Eagle and the Vampire Finch .

More specifically, the yellow-crowned night heron belongs to the sub-class Neornithes, the most recent common ancestor of all living birds. Traits observed by these modern birds would be a beak without teeth and a high metabolic rate and rate of growth (Clarke 2004). Neorinthes would be considered modern birds, except Palaeognathae (mostly flightless birds) such as Apteryx haastii (Great Spotted Kiwi) and Galloanserae (land and water fowl) such as Gallus gallus (Common domestic Chicken) (Feduccia 1999). This sub-clade has over 9500 species defined into 20-28 different orders (Van Tuinen 2009).

The yellow-crowned night heron is put into the class Neoaves, an order that separates land and water fowl from all other birds. Within the Neoaves class, night herons are described in the order of Pelecaniformes, meaning they are medium and large sized waterbirds. This class was formally described by four webbed toes but further scientific evidence through DNA hybridization and molecular data shows that more birds, such as the yellow-crowned night heron, are included in this order (Sheldon et al. 1999; Mayr 2008). Other large wading birds like storkes, or Ephippiorhynchus senegalensis (Saddle Billed Stork) are included in this order. Other common features in this order include a bare throat patch, a small glandular patch above the esophagus on the gullet of the bird, and nostrils that are mostly dysfunctional slits that cause the birds to breathe through their mouths (Ericson et al. 2006).

From the name, we can tell that the yellow-crowned night heron belongs to the family Ardeidae, the group including herons, egrets, and bitrons (Watts 1998). Unlike other wading birds, such as cranes like Grus Americana (Whooping Crane), the yellow-crowned night heron have a characteristic “S” shaped neck. This occurs during flight due to a modified 6th vertebra (Sheldon et al. 1999). Other well-known birds of the Ardeidae family include Butorides virescens (Green Heron). Yellow-crowned night herons belong to the genus Nyctanassa. They are defined by their nocturnal feeding as well as geographic location living in the Americas in mostly warmer coastal regions.

Finally we get to the species, Nyctanassa violacea, meaning yellow-crowned night heron; they are defined by their yellow-white "crown" or plumage on their head as well as smaller size. They are also identified by their mostly black head, and white patch on each cheek, and white stripe underneath their eyes (BirdLife International 2012). The word Nyctanassa stems from their original genus Nycticorax which is Greek for night raven, named that due to their nocturnal feeding behaviors. The Common Raven belongs to that group as well. The species violacea means violet most likely do to their iridescent black head.


Figure 1.2 This tree shows the relationship between crocodilian reptiles to neornithes, which night herons belong

                to. Though the fossil record there is evidence that various common ancestors occurred, such as

                jeholornithiformes and enatiorinthes. These common ancestors slowly lost reptilian traits and adapted

                smaller body size, feathers, bare legs, wings and a beak like structure. We can see from this tree that

                many of the common ancestors are now extinct leaving only crocodilia and neornithes (Zheng et al.


To see where the yellow-crowned night heron resides, vist the habitat page, or go home.