Tuesday, April 24, 2012

Fish Crow nests in Ohio!

Yesterday came the exciting news that Fish Crows, Corvus ossifragus, had been found in Ohio. This species had long been anticipated to arrive, and eventually nest, and that expectation became reality this week when Andy Jones discovered the birds described in this post. Last year saw a few reports of flyby Fish Crows along the Lake Erie shoreline, but those birds were not chaseable or otherwise independently verifiable, and I don't believe any recordings of vocalizations were made.

Well, Andy's birds are a snap to find, and are enlivening the neighborhood depicted in the shot above. Jones, who is the ornithologist at the Cleveland Museum of Natural History, came across these Fish Crows in a quiet well treed east side Cleveland neighborhood, Shaker Heights. He broke the news yesterday, and Bernie Master and I were in the car and headed north bright and early this morning. The crows were easy to find; we saw them as soon as we turned onto the street in the photo, and they put on a show the entire time we were there.

Here's the Google Earth view of the lay of the land - about as suburban as one can possibly get! This habitat choice is not entirely unexpected with Fish Crows, though - like their close relative the American Crow, Corvus brachyrynchos, they are increasingly exploiting cityscapes as nesting habitat.

Bernie and I parked a discreet distance from the nesting tree, and stood quietly about watching the show. There were four Fish Crows, and they couldn't be missed. The birds flew about the neighborhood, perching conspicuously in the tall oaks, occasionally scrapping with one another, and while not overly vocal, gave their telltale nasal calls fairly often.

Fish Crows are primarily birds of the immediate vicinity of the Atlantic and Gulf Coasts, but they've been undergoing pronounced range expansions into the interior U.S. in recent decades. Until they invaded the north shore of Lake Erie 20 or so years ago in the vicinity of Point Pelee, Ontario, Canada (where they are still rare), the Fish Crow was endemic to the United States. They've been steadily spreading along larger river systems - I saw them along the Shenandoah River in Virginia two weeks ago, where they are relatively recent colonizers - and are making their way into the Great Lakes, such as along the southeastern shore of Lake Michigan. CLICK HERE for a 2010 blog post that I made about Fish Crows, predicting (I was hardly unique in this) their eventual appearance in Ohio. That post also has more detailed distribution information.

I worked hard to bag a nice in-flight shot as the birds winged their way around the neighborhood, and was finally rewarded with this photo. Fish Crows greatly resemble American Crows, and voice is by far the best way to separate the species. Once we heard them, just like Andy Jones, we knew there was no doubt as to the identity. CLICK HERE to hear a recording of Fish Crow.

But there is a difference between the two species that involves the primary flight feathers, and this character can be seen in the above photo. The primaries are numbered, starting with the shortest foremost feather at the leading edge of the outer wing. It is "P10", and from there the primaries are labeled "P9", "P8" and so on as one moves along the feathers towards the rear edge of the wing. In the American Crow, P5 is noticeably longer than P9. In Fish Crow, P5 is about the same length or shorter than P9.

 Photo: Bernie Master

We saw the birds collect a number of twigs and transport them to the nest, which was obviously still under construction. Bernie managed to catch the crow above in the act of stick-harvesting.

There were four Fish Crows, and although we saw an occasional seemingly hostile encounter between birds (which may have been more along the lines of play), they mostly interacted peacefully. At one point, two of them sat close together in an oak, while the other two birds sat together in a nearby tree. It may be that one set of birds are "helpers"; juvenile birds hatched last year that are not yet ready to breed and that hang around a breeding pair of sexually mature adults. The phenomenon of helper birds is well known in American Crows, but not so much with Fish Crows. However, a perusal of the Birds of North America monograph on Fish Crows makes it abundantly clear that many facets of this species' biology is not well known and much more study is needed.

This towering red oak harbors the nest, which can be seen near top center of the tree. Apparently this nest location is pretty typical for Fish Crow - near the summit of a large tree. The pickup truck belonged to a guy who was doing work on the driveway of the house where the tree sits. In spite of that, and the activity of neighbors, cars passing by and other action, the crows did not seem overly bothered and continued to work on the nest.

If you do visit, stay several houses or more away from the nest. There is no reason to venture near, as the birds are conspicuous and fly about the neighborhood. My photos were made from some distance down the street. Also, and I know this goes without saying, it's important to respect the neighbors. There will probably be lots of birders visiting this quiet neighborhood to observe the Fish Crows, and the locals certainly aren't used to an invasion of binocular-toting birders. Word is out among the locals regarding the crows, though, so at least the residents will know what is going on.

Here's a telephoto shot of the aerie, which is about 50 feet up a red oak. This is the first documented Fish Crow nest in Ohio, thanks to Andy Jones. I wonder if these birds nested locally last year, though, and if the "helpers" are local spawn. My hunch is that this won't be the last Fish Crow nest in Ohio, and I'd bet they slowly begin to increase, as Common Ravens are doing in eastern Ohio.

What does seem a bit surprising is the lack of a prominent river or water body near the nest. That red line stretches from the nest site for seven miles until it hits the Lake Erie shore. No good-sized streams are very near, either. Oh well, the crows know best.

Kudos to Andy Jones for this great discovery, which indisputably adds another species to the Ohio list (#423 by my conservative reckoning). And on a comparatively trite note and not that anyone's counting, but these Fish Crows were #368 for my Ohio list.


1 comment:

Laura said...

Jim -- Thanks for an interesting post about Fish Crows and their appearance in Ohio. I'm out of town, so I haven't seen them yet, even though they are nesting only a couple of miles from my house! I was lucky enough to get a recording last spring (May 23) of vocalizations of three or four probable Fish Crows that flew over my house. The flyover was at about 6:15 AM, and, luckily, my night flight call recording equipment was still on. I was walking down the street and heard and saw the birds, then checked my track later. I submitted the recording to the Ohio bird records committee, and I believe they haven't ruled on it yet. Here's a link to the track for those who are interested: http://snd.sc/JoIvlo

Thanks again for the blog -- It's always interesting.

Laura Gooch