Wednesday, December 12, 2012

Black-crowned vs Yellow-crowned Night-Heron

The Black-crowned Night-Heron is another widespread, common North American heron. We saw them more often when we lived in South Dakota then now in Minnesota. Especially away from their breeding colonies, these birds can be hard to locate—they tend to be nocturnal. Populations are reduced now compared with years past—they are top-level predators (eating mainly fish and whatever else they can capture) and tend to accumulate poisons in their tissues. DDT contamination led to population crashes in the 1960s; now wetland destruction threatens them. On the other hand, these night-herons are not picky about their choice of breeding locations and will tolerate human disturbance (Hothem et al. 2010).

Adult Black-crowned Night-Herons are not difficult to identify. Notice the tear-drop shaped stripes on the immature bird in the next photograph. Also the head is relatively large and the body shape is stocky. Birders often have trouble telling the immature birds from young Yellow-crowned Night-herons
The last bird is a young Yellow-crowned Night-Heron. Its back is more spotted than tear drop-shaped. Its head is slightly smaller and it appears to be longer-necked. I will post a photo of an adult Yellow-crowned Night-Heron in my next post.  Both of the Black-crowned Night-Herons in this post are from South Dakota; the Yellow-crowned Night-Heron is from the Everglades National Park in southern Florida.

No comments:

Post a Comment