Form and Function

Photo of a yellow-crowned night heron in flight.  Photo credit to Flicker user KhurramK.There are 12 species of herons found in North America; the yellow-crowned night heron differs from other species by its nocturnal activity as well as its yellowish crown stripe (Kushlan 1976; Cornel 2009). They have medium sized bodies, with both sexes weighing in at around 22.9-28.2 oz and 21.7-27.6 inches tall (Cornel 2009). Both male and female look alike, having a white crown, red eyes and a white stripe below their eye. The adult body is entirely slate grey, and juvenile is a mix of brown and grey. They are well camouflaged in their grey/brown coloring and are very secretive birds, as well as nest in small scattered colonies in forested habitats (Watts 1995).

Like all herons, the yellow-crowned night-heron is a wading bird with tall stocky legs and a long slender beak. These adaptations facilitate feeding using two techniques: the stand and wait technique and the walk slowly technique (Meyerricks 1960).

Photo of a yellow-crowned night heron wading in water.  Photo credit to Douglas Mills of Flickr.In addition to wading and walking along the coast, they are also flying birds. In flight, they keep an S shape in their neck and fly with feet and legs apart. Though yellow-crowned herons are shy, they have a loud call that can separate them from other birds. Their call includes a harsh squawk, which is higher pitched than that of the black-crowned night heron (Sutherland and Gunn 2010; Elliot et al. 2004). The call is often emitted when the bird is disturbed (Elliot et al. 2004).  You can listen to a yellow-crowned night heron call here.

This organism possesses a feathered coat that allows for a seasonal molting to occur. Like most herons, their pre-formative molt occurs mid September to late February and the second pre-basic molt occurs between late April and late June, after which they are classified as adults. Once a yellow-crowned night heron reaches adulthood, no contour feather molting occurs. They exhibit a complex basic strategy of molting (Pyle and Howell 2004; Howell et al. 2003). These characteristics develop throughout the life cycle and assist in reproduction as described on the next page.