After completing the first half of our training classes, I glanced back over my notes and jotted down some of things that I’ve found most interesting so far!
Golden Cheeked Warbler, from http://www.geckrich.com/
It looks idyllic to me when I see squirrels chase one other through the clover of my backyard, but an expert in urban systems sees things differently. Clover grows on damaged land; it’s one of the plants that helps replenish soil. Squirrels are generalists. Unlike specialists, which always out-compete other species if they are in their natural habitat, generalists thrive in landscapes that humans have transformed and urbanized. It’s pretty easy to know if an animal is a generalist or a specialist. All I have to do is ask myself “is it in my backyard?” Raccoons, opossums, squirrels, rats- yes, generalists. Golden cheeked warblers- no, specialist.
A squirrel isn’t particular about where he’ll breed. Any random place will do, including my attic. The golden cheeked warbler, on the other hand, is picky. That gal won’t settle down just anywhere! She needs the juniper oak woodlands of Central Texas, and while she can out-compete any generalist in those woodlands, she simply refuses to nest in the circle made by the giant fluorescent B in the HEB parking lot sign. But a grackle will, that uncouth generalist! So next time you find yourself complaining that urbanization sometimes causes all cities to look alike (same old strip malls, chain stores and cookie-cutter houses), then look to the golden cheeked warbler as your kindred spirit. Urban systems that don’t consider the needs of specialists contribute to their decline. Our fastidious warbler is endangered.
Likewise, in urbanized areas, we see an increase in meso-predators and a decrease in apex predators. This is why I have to keep opossums and raccoons out of my chicken coop, but I never worry that a mountain lion is going to attack my dog. I found myself thinking that generalist meso-predators are perfectly adapted to be a nuisance, and I wondered what would happen if they developed an evolutionary mutation that made them beneficial to humans instead. A raccoon is a cute-enough critter, and it’s clever. If it suddenly showed a willingness to be potty-trained and developed a penchant for hunting all the mice around your house, would you keep it as a pet? Isn’t this how we formed our relationship with cats? Tens of thousands of years ago, weren’t dogs just a generalist meso-predator that thrived in human-altered landscapes?
Aquatic landscapes are changing, too. A healthy river stays rich and wide because the water flows along picking up sediment from the banks and carrying it along its course. But the roots of invasive plants prevent this natural erosion, turning our U-shaped rivers into V-shaped canals and changing the composition and flow of the river. This might sound like good news if you were hoping for a George Clooney-esque Venice boat wedding, but it’s bad news for many of the endangered species of mussels that hitchhike on native fish during part of their life cycle.
I was surprised to learn that the Edwards Aquifer and lower Colorado River are still severely low. Turns out, we’ve had a decent amount of rain in the last several months, but it has not been sufficient to replenish the watersheds after years of drought. More importantly, it is not raining up river. The places that need it most are still experiencing very low levels of rainfall. If you want to join a fun citizen science project, you can put a rain gauge in your own backyard and report local precipitation data to CoCoRaHs.
Speaking of rain, yesterday I was working in my garden and watching the storm roll in. Ordinarily, I’d keep working until the raindrops fell on my head despite the sounds of thunder and flashes of lightning in the distance. But this time, I remembered that the majority of lightning strikes in our area happen to people “under the blue”- before the rain starts. I set down my spade and went inside!
Trade winds steer the flow of storms and clouds in the northern and southern hemisphere, but due to the Coreolis effect, cyclones spin in different directions depending on which side of the equator you are on. And if you are on the equator itself, that same Coreolis force prevents the cyclone from forming at all. I’m pretty sure that to really understand this, you’d have to be part physicist and part pirate, and perhaps that’s what a meteorologist is. For myself, I was satisfied to learn that while low pressure systems do spin clockwise in Australia, their toilet water still swirls the same direction as ours when flushed since modern plumbing forces prevent the Coreolis effect. Another life-long mystery explained!
Of all the things we’ve learned, one of the topics that has interested me most is fire. It’s natural that this would be a subject of importance here in Bastrop, and I doubt there is a trainee among us who wasn’t touched somehow by the 2011 fires. The fires have become one of those events by which people count time, and references to things lost in the fires are sprinkled throughout daily conversations in Bastrop. So it has been fascinating to learn about the details of the fire- its extent, causes and control. Everyone who has spoken to us has emphasized the need for regimented controlled burns, especially in the state parks. While other pine species need fire to open their cones, loblolly pines require fire to germinate. The rings of old trees in the state park show that the pre-settlement Lost Pines naturally experienced smaller fires every 15 years. Settlers began to prevent burns, and in the absence of fire, pine forests convert to oak forests, the undergrowth loses its natural diversity, and the forest floor becomes a tinderbox. We know that all too well!