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Sunday, June 11, 2006

Birds of the Mid-Atlantic #12: Black-crowned Night-heron

So far in this series I have mostly written about diurnal birds - those that can be seen during the day. Most North American birds are in fact diurnal species, since birds tend to encounter the world through sight and sound, much like humans. But aside from the diurnal species there is a world of crepuscular and nocturnal birds, some of which are rarely encountered, and others that are more often seen than heard.

Two such species are the night-herons - the yellow-crowned night-heron and the black-crowned night-heron. These two species emerge in the evening as shadows lengthen and return to their roosting spots at sunrise, after a full night of hunting fish and invertebrates. Since night-herons are colonial breeders, the best bet for seeing them during the day is to visit a known nesting or roosting site.

One local spot where seeing black-crowned night-herons is virtually guaranteed (in the proper season) is the National Zoo in Washington, DC. A colony has been nesting over the outdoor flight cages near the bird house for several decades. At this time of year, one can see adults like the above bird perched in the trees around the bird house. Later in the summer, once this year's chicks fledge, immature night-herons will frequently patrol the duck ponds, and do not flee closely-approaching humans. Yes, these are wild birds, despite their nesting location and despite their tameness.

If you enlarge the photograph and look closely, you can see that this individual has been banded. These two photographs show the key identification points for adult black-crowned night-herons. Night-herons have a stocky, hunched appearance, even when not preening, and have a thick, heavy bill. Adult black-crowned night-herons have an obvious black crown, as well as a black back. (Note that the yellow crown of yellow-crowned night-herons is not always apparent.) Like great blue herons, black-crowned night-herons sport long breeding plumes at the backs of their heads.

While black-crowned night-herons are widespread across North America, they are particular about their habitats, and in particular they much prefer the lower elevations of the coastal plain and prairies to mountain ranges.

This entry is crossposted in A DC Birding Blog. Images are by the author.



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