Turf Birds

Here's a find from a few days ago:

This is an American Golden Plover (Pluvialis dominica). He's migrating through, on his way from the tundra of northern Canada to the pampas of Argentina. As a plover, he would be considered a shorebird, and we did in fact find him on a shore (a lakeshore, but...):

This was at Illinois Beach State Park, here in Lake County. Around here, these birds aren't easy to find. Most of the large plovers that move down the lake turn out to be these guys:

These are Black-bellied Plovers (Pluvialis squatarola). They breed in the same Arctic tundra, but many of them spend the winter along the Gulf and Atlantic Coasts instead.

As I said, Golden Plovers are hard to find here in Lake County. But elsewhere in Illinois... A significant portion of the world's population of this species migrates through central Illinois, where a good day scouring sod farms (with a scope, preferably) can yield several hundred of them. Sod farms, of course, can hardly be considered shorelines, but some "shorebirds" actually prefer them. Here's another example:

This is a Buff-breasted Sandpiper (Calidris subruficollis), another sod farm specialist, and another species more easily found in the Midwest than just about anywhere else.

This preference made sense, when this area was full of prairies, prairie fires, and bison. Now that the bison are gone, most of our prairies are tiny little patches, and prairie fires are carefully managed, they seem to be dependent upon our desire for short, green grass. But sod farms are, after all, businesses, and they have no choice but to respond to the economic environment. These days, many of our local sod farms have been slowly converting to corn, as demand for sod goes down. What this means for Golden Plovers and Buff-breasted Sandpipers, we don't really know. But it does illustrate an intriguing way in which economics can impact the natural world we live in.

A Melodrama For Three Parts

Here's a beautiful little critter that came by our hawkwatch yesterday:

This is a Merlin (Falco columbarius), another small falcon. Whereas Kestrels are all about elegance and grace, Merlin are all about power and speed. We sometimes say that Merlin shouldn't be a two-syllable word, because you don't have the time to say it!

Here's one dining on the wing -- they do this a lot as they migrate south.

What's he eating? Probably a close relative of this guy:

This is a Canada Darner (Aeshna canadensis) that also showed up on the hill yesterday. We don't see many of them, but we do see a lot of Common Green Darners, in the same family. (Although in a different genus -- they're formally known as Anax junius.) They appear to be a favorite snack for migrating Merlin.

Darners are also voracious predators of smaller insects, with darners specializing in flying prey.

This particular guy, though, fell afoul of yet another predator:

This beauty is a Banded Argiope (Argiope trifasciatus). She's a big spider, with a body close to an inch in length, and she's going to need every bit of her size and venom:

You may have heard people talk about the food chain. Some might even understand the concept. But the food chain is a wonderful example of what Jack Cohen and Ian Stewart call Lies to Children. (aka education) Nature is so much more complex than a simple chain -- here we have a notable predator (the darner) being eaten by two other predators (the Merlin and the spider), with nary a producer (i.e. plant) in sight -- any plant is at least two steps back in the system, and possibly more. If we had followed this darner through his entire life, we might well have found him eating a baby Argiope trying to reach a new home. Or we might have seen him eating a mosquito that had just fed on a female Merlin returning to her nest with another dragonfly for her hungry chicks.

Lies to Children refers to simplified stories that we tell children (or college students, etc.) so that later on, they're ready to understand the more complicated truth. Except that science is, in the end, about telling each other stories about how the world works, and since the world is bigger and more complex than our poor brains, we have to tell each other lies as well. We can, of course, hope to find more accurate lies, and who knows, maybe sometimes we do hit the real truth. After all, we really do know more about how the world works than we ever used to. But without a teacher out there to tell us how we did, we can never really know we've got it right. We can figure out that we're less wrong than we once were, though, and that's a useful thing indeed.

Making Sense of Hawks

We started our hawkwatch Saturday, and we've had a few things to look at so far. (The first couple of weeks are always rather slow -- if you want to be sure that you're catching the entire migration, you've got to put up with some slow days.)

This beauty came by last Sunday:

He's an immature Red-tailed Hawk (Buteo jamaicensis). He didn't appear to be migrating, though, which isn't surprising. We know they nest in the park where we count.
On Monday, this lovely lady took a look at our site:

This is a female American Kestrel (Falco sparverius). She had caught something, possibly a grasshopper, and we watched her eat on the wing as she went by.

The Kestrel is, as the Latin name suggests, a falcon, in the family Falconidae and the order Falconiformes. She's got a strongly hooked, sharply pointed bill, strong feet with large pointed claws, and long, sharply pointed wings to enable her to fly very fast and maneuver very efficiently. The hawk is in the family Accipitridae (Accipiter simply means hawk in Latin). While the wings aren't sharply pointed, the bill and feet are very similar, and the wings are still long enough to allow for impressive flying abilities. Both families also specialize in eating not only other animals, but frequently other chordates. It's probably not a surprise that traditionally, then, the Accipitridae has been included in the Falconiformes.

What may be a surprise, though, is that they are no longer placed there. In fact, Accipitridae is now in the order Accipitriformes (formed when they were removed from Falconiformes). What's probably more of a surprise is that the Accipitriformes are now considered to be the sister group to a clade of owls, trogons, hornbills, kingfishers, and woodpeckers, while the Falconiformes are seen as the sister group of a clade composed of songbirds and parrots.

And what should we make of this guy:

This is a Turkey Vulture (Cathartes aura), in the family Cathartidae. The family is strictly New World, with 7 species, 3 of which are found in North America. (There are a few finds that suggest they were more widespread in the Pleistocene.) He has a nicely hooked bill, but the feet aren't nearly as strong, and while he's also a chordate eater, he very rarely kills for a meal. Vultures are patient critters that wait for animals to die on their own before they dine.

Historically, they have been placed in the Falconiformes. Before that order was split, though, the Cathartidae were moved into the Ciconiiformes, with a number of authors arguing that they were actually similar to storks. (This discussion only applies to the Cathartidae -- Old World vultures have always, to my knowledge, been included in the Accipitridae.) Some authors subsequently have placed them in an order all their own, Cathartiformes, while others have actually argued for a label of incertae sedis (aka "we have no idea what these things really are!"). The same large-scale analysis that led to the Accipitriformes, though, supported placing the Cathartidae back with the hawks, and at the moment, the AOU checklist has them in Accipitriformes with the hawks, eagles, kites, and Secretary Bird.

Through it all, we've been faithfully counting all of them, and we'll of course continue to do so. Knowing about the evolutionary history is wonderful, but keeping them around is a pretty important goal as well, and we hope that keeping track of them is a small part of that. With luck, I'll never have to try to communicate the thrill that we used to get watching them sail past.

Oh, and just because, here's a King Vulture (Sarcoramphus papa) from the St. Louis Zoo: