Sunday, February 26, 2012

Those Terrible Pterosaurs

Notice the fearful claws & and the murderous look in his eye? Black-capped Chickadee photo by Eric Bégin

Yesterday, as I pulled out of the garage, something in the driver’s side view mirror caught my eye. A fuzzy ball of black and white—a bit larger than a prickly gumballs—came crashing down from the sweet gum tree. Then the ball broke apart into at least three Carolina Chickadees. They rolled on the ground, kicking, punching, and talking about each other’s mommas.

I recently attended a presentation by David Peters about the evolution of birds, sponsored by Webster Groves Nature Study Society, St. Louis Audubon and Eastern Missouri Society for Paleontology. The boundary of the Cretaceous and Jurassic is not my area, so most of what was said went right over my head. I apologize in advance for the mistakes I'm about to make. Peters’ theories about the taxonomy of pterosaurs is somewhat controversial; again, for reasons that are beyond me. His website is fascinating. He explained how the shoulder (coracoid bone) and fused clavicles (furcula, or wishbone) allowed the arm/front leg of a reptile to become the abducted, elongated wrist/claw/wing of a pterosaur.
Largest pterosaur, by Mark Witton

Now I hadn’t really thought of pterosaurs as the direct ancestors of birds. They looked like bats to me. I didn’t realize they had the modified scales we call feathers. Think of Quetzalcoatlus—the largest pterosaur, with a 40-foot wingspan, a spear-shaped head, and a ring finger that functioned as the wing. It looked even less like a bird when Peters analyzed the fossils of its tracks, demonstrating that it walked on its wings/knuckles like a reptile walks with its front limbs. 

When he showed Nemicolopterus crypticus, another pterosaur with a wingspan roughly the same as a chickadee’s, I began to see the family resemblance. The ruckus under the sweet gum makes more sense now that I no longer see them as charming chickadees, but tiny, terrible, pterosaurs.

Thanks to Eric Bégin and Mark Witton for licensing their photos with Creative Commons.

You might also enjoy:
For a Few Bags of Gumballs

When Butterflies Attack!

Saturday, February 11, 2012

The Not-So-Common Common Ground Dove of Weldon Spring CBC

Truman was President, Muddy Waters sang "Rollin' Stone," Lefty Frizzell sang "If You've Got the Money," "Sunset Boulevard" took the Golden Globe, and the Webster Groves Nature Study Society  counted birds in the cold December winds at Busch Wildlife Conservation Area near Weldon Spring, Missouri, Dec. 29, 1950.

Every year since then, Webster Groves Nature Study Society, better known as WGNSS--pronounced, "Wig-ness"--has participated in the National Audubon Society's Christmas Bird Count (officially,  MOWS, "Missouri-Weldon Spring") by surveying the area we call "Busch." There are about 11 square miles to survey, including 3,000 acres of forest, 32 artificial lakes, and 100 bunkers once used for storing TNT during WW2. Throw in plenty of gravel roads, a thousand acres of grassland plus 200 acres of restored prairie and the same amount of old fields, and you've got a diverse and accessible birding area--all within 50 minutes' drive from the St. Louis Arch.The plan in a survey such as this is to count each species of bird seen, as well the number of individuals. We divide into territories, and take precautions not to count an individual more than once. For example, I might spot 3 Blue Jays in the tall oak by the creek. Some time later I drive past the same spot and see 5 Blue Jays. I record an additional 2 birds, not 5. On the way to my territory, I see a Bald Eagle overhead. I don't record that bird, but I do notify the count compiler in case the team in that area missed it. If so, Bald Eagle will be added.

This year we had 11 participants who counted 2,441 birds of 49 species, including one that has never been recorded on the Weldon Spring count, the Common Ground-Dove. For that matter, it's likely the only individual of its species ever to have been recorded on a Christmas Count in Missouri. It's a bird that's normally found in the extreme southeast and southwestern US and coastal Mexico. Records show that the species has never been recorded in St. Charles County. Thanks to Josh Uffman for making this information available online.

Our little dove--smallest in the US; half the length of the abundant Mourning Dove--was very kind to us, considering all the factors. It had been dallying in the fields of Busch for weeks, putting up with hunters and as well as unruly birders. It was our target bird, but rabbit hunters with their noisy beagles caused it to lie low. Fortunately, some of the group were very patient, including Bob Nieman who snapped this picture just as the sun set. Bob was visiting the area for the holidays--thanks for your help in making this a memorable count!

On my route, I was delighted to witness a  behavior I'd never seen before. I paused along the road where fields gave way to forest. American Robins and Cedar Waxwings crossed back and forth, feeding on and the waxy blue berries (really cones) of Eastern Red Cedar and the abundant red berries of invasive bush honeysuckle. Amidst the busy, noisy robins, two sleek waxwings rested on a branch. One passed a berry to the other's beak, who then passed it back. They did this for several minutes. Male and female Cedar Waxwings look identical, but the two were probably a pair engaged in courtship behavior (A Guide to Bird Behavior, Vol. II, by Don and Lillian Stokes, 1983).