Friday, May 18, 2012

The Yellow-crowned Night Herons of Midtown Memphis

Wednesday night my dad and I went to the last meeting of the Memphis chapter of the Tennessee Ornithological Society (MTOS) until September. It was the first one I've been to, despite having been a member since December of last year. We'd never been able to make it until then.
The meeting was great and I met a lot of birders. Even, as I was surprised to find, another young birder. Funny, he was the first one I've ever met in person. I was delighted to see that about 25 people showed up. "See," I told my dad. "I'm not that weird."

At every meeting, the MTOS does a talk about something of interest. Wednesday's talk was about the Yellow-crowned Night Herons of midtown Memphis. Apparently, night herons are nesting all over midtown, though people don't often notice them. A lot of them nest in people's yards. Now, that would be cool.
The night herons (or YCNH when abbreviated. Find a chart of standard bird name abbreviations here) have been nesting there for a few years now. I've never seen them, so I made a mental note to suggest it some weekend when we've got nothing to do. The YCNHs usually nest deep in hardwood forests or swamps, and it was a shock to find them in the middle of fast-growing Memphis. Their range includes most of the southeastern U.S., but only the western part of Tennessee. Their range stretches as far north as New Jersey, but only along the east coast. YCNHs also usually nest very high up in trees, but in Memphis they are nesting from only 18 to 20 feet above the ground. The presentation included a lot of great photos, most taken in the breeding season of 2011. They couldn't take photos of the young when they had just hatched, because obviously you can't see them from ground level. There were also photos of courtship and mating, and I learned that male YCNHs, when courting, spread out the plumes on their backs (called nuptial plumes) into a fan that looks almost like a peacock's tail. The guy giving the talk said they get more of these plumes as they get older, so if you see a particularly old male doing it, it's apparently quite amazing.

Young night herons, when they reach about 2 weeks, begin to explore. They move around the nest, which is pretty big, but still crowded with 4 or 5 baby herons in it. Little by little, they make their way to the branches around the nest, where they start testing their wings by spreading them out and making a few expirimental flaps. They, like most babies, are fascinated by their enviroment. A few photos showed the babies perched on branches, looking down with a quizzical expression at cats, dogs, humans, and other curiosities. Occasionally, the baby night herons fall of the branches while doing this. Once they're on the ground, they're pretty much toast. They can get eaten by dogs, cats, or other predators, or just starve or drown.

Yellow-crowned Night Herons are very similar to Black-crowned Night Herons. There are some distinguishing field marks, however--the first one that comes to mind being the color of their crowns, of course--but when they're most active (just after sunset), it can be hard to see colors. So a good way to tell the two apart is their shape. If you stumble upon a night heron, looks at its legs and feet when it flies. Black-crowns tuck their feet up under them, while Yellow-crowns let them trail out behind. It's a good trick to know when looking for night herons. 

YCNHs have a whole lot of unique traits. They are one of the least-studied North American birds, so they might have more. For instance, when a YCNH drops a piece of nesting material, it doesn't fly down to pick it up. This is strange, because every heron species we know of picks up the material if it drops it. Not Yellow-crowns, though. YCNHs also don't prefer getting their feet wet. They live in marshes and swamps, eat crabs and crayfish, and are called long-legged waders, but don't like to get their feet wet. Kind of strange. Another trait they have is also claimed by other heron species. One of their first methods of defense is their stomach. If some kind of predator is climbing their nest tree, they'll lean over the side of the nest and--WHAM. Deflate their stomach. If you're a researcher or biologist of some kind, and you want to see into a heron nest by climbing up their nest tree, they'll do the same to you. The guy giving the talk said it happened to him with Cattle Egrets in Hawaii. He said it was worse than being sprayed by a skunk. Ew.

So now I have another bird on my wish list.

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