Black-crowned Night-Heron

A Black-crowned Night-Heron. Image taken at the San Francisco Zoo.

The Black-crowned Night-Heron is one that you are likely to come across if you are interested in birding. Although they are usually nocturnal, they are the most common heron and can be found throughout 5 continents (the missing two are Antarctica and Australia). They are very adaptable birds and are known to eat everything, even garbage and organic refuse from land fills, although they primarily eat fish. In winter time they roost communally and during breeding season they nest colonially, each pair building their large nests in trees with several other pairs. In fact, they are thought to be too abundant by some, particularly owners of fish hatcheries. They like to nest nearby this wonderful abundance of food and are thought of as pests when they do.

Despite being easy to find, if you see a tree with nesting birds, it’s a good idea to admire them from a distance. For one, the young are known to be exceptionally aggressive and will defecate and regurgitate on humans coming to close. (Unfortunately, I was not aware of this when my best friend and I stumbled upon a tree of nesting birds in Chile and let’s just say I was the lucky one.) This is actually quite a fortunate circumstance for scientists who are researching the composition of the birds’ diet. Personally, I have to love those that are so driven by the excitement of answering a question that they’ll enthusiastically dig through baby bird vomit. 🙂 The other reason to steer clear of nesting birds is that despite them often being found relatively near humans, if a human visits a new nest or a recently laid egg, they will often abandon it. If there are frequent visits by human pests, it will also discourage late nesting herons from settling down. So it’s not good for you or the parents-to-be if you’re hanging around.

A Black-crowned Night-Heron

A Black-crowned Night-Heron at the San Francisco Zoo.

Once they do settle into a nest, though, these birds are thought to be monogamous. The male performs a courtship display for the females (who are usually rejected at first) and the female of choice is eventually allowed into the territory, where they’ll preen each other and rub beaks.  You can tell when a happy couple has paired because at the time of pair formation, their legs turn pink! Like most birds, the pair will work together to take care of their young. If other chicks are placed in their nest, say by a mischievous researcher, they will also brood young that are not their own.

Also, not on night herons, but the Belize Zoo was recently hit hard by Hurricane Richard. There was major damage to the facility and they are looking for help to put them back together. There are images of the damage they suffered and a link to make contributions here. This little zoo has rescued many animals and participates actively in research, conservation and education programs.