June 9, 2017

Heron of the Night

By Dave Erler

The first time I heard the call of a Black-crowned Night-Heron (Nyticorax nyticorax) I was about eight years old. It was just after an evening of fishing for Black Crappies on a lake in Minnesota. I remember it happened as I loitered along the shore after my father, older sister, and younger brother had all headed back the trail through the woods. A loud guttural “quock” sound came from overhead and although I don’t think I was scared I do know it startled me. I had no idea what made the call. I didn’t hear l that cry again until some 14 years later, but I knew immediately I had heard it before. At that time I was working for the University of Minnesota Extension Service at a summer youth camp near a Minnesota lake. I was with a group 10 to 14-year-old farm kids. The sound scared the bejesus out of some of the kids. They, of course, immediately wanted to know what it. Being the “nature specialist” I suddenly felt pressure to supply an answer. I have to admit I still didn’t know what it was. I knew it wasn’t an owl and I knew it wasn’t the low-pitched “croak croak” of the Great Blue Heron. I responded that it was just the call of a “water bird,” which seemed to reassure the kids that it wasn’t anything too dangerous. That incident gave me incentive to find my set of Peterson birdsong tape cassettes.

Since both times I had heard the sound it was at night, near a lake, clearly came from above, and was similar to the call of Great Blue Herons I’d heard when they were flying overhead, I figured I should start there. Sure enough, the guide with my Peterson tapes listed my options. I picked the cassette with bird calls from Loons and other water birds and slipped it into the tape player. I pushed the button to fast forward, randomly stopped it, and pushed the play button. Low and behold by pure luck the very same call I had heard came from the speaker. I hit the stop button, put it into rewind for two seconds, and the monotone voice identifying the calls put a name to the mystery call.
Black-crowned Night-Herons are small, squat, chubby herons with thick necks, rather large heads and heavy pointed bills. As their name suggests, the adults have distinct well-defined black crowns as well as black backs with contrasting white undersides. Their legs are shorter than the larger Great Blue Herons’ are.  In flight their short legs barely reach the end of the tail. While in the air they hold their heads back against their bodies making them appear to have no neck. Like most herons, they have a rather slow, steady wing beat on broad, rounded wings.
Black-crowned Night-Herons are found across much of North America and on every continent except Australia and Antarctica. Although not as commonly seen as the more familiar Great Blue Herons, Black-crowned Night-Herons are probably the second most common heron in North America. Due to their nocturnal habits they are not often seen. During the day they usually find shelter by perching in trees, hidden among the foliage, often in groups. In the evening and night they forage in marshes or along the edges of lakes and streams. Their dagger-like pointed beaks are serrated, allowing them to snatch and hold slippery prey including fish, crawfish, frogs, tadpoles, and water snails. Once they catch their prey they swallow it whole.
When you visit the Science Center this year make sure to visit the Celebrate Birds Exhibit. The attached aviary will be a “heronry” displaying several species of herons, including an immature Black-crowned Night-Heron. If you visit over the course of the summer you will notice a change as it molts from its immature brownish, streaked feathers to its very different adult plumage. Like most of the birds that live here, this bird is non-releasable. It (he or she – it’s hard to tell) arrived from a wildlife rehabilitation center in Glen Ellyn, Illinois, where it was treated, but deemed non-releasable due to a wing injury limiting its flight ability.

In the years since I first heard those guttural “quock” calls, I still have only seen Black-crowned Night Herons perhaps a half dozen times. But to this day I have yet to hear another one call, but rest assured if I do, I will know what made that sound in the night.

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