Sunday, September 28, 2014

Revisiting Tandy Hills

View of downtown Fort Worth from Tandy Hills
Tarrant County, TX includes parts of both the Grand Prairie and the Western Cross Timbers ecoregions.  Thin clay soil over caliche supports prairies, while deeper, sandy soils can host scrubby oak-juniper forests. The difference is all in the water capacity. A tree can make a go of it if it spreads its root system in the sand, but the shallow clays just can't hold enough water. In this way, the soils structure the plant communities irrespective of their shared precipitation regime.

After returning to Tandy Hills last weekend, I looked at soil maps of Tarrant County to try and understand why it has stayed so open on the ridge top. Nothing struck me as different at the map resolution I could find- there were no unusual soil inclusions marking Tandy as different from the surrounding area. I do know that in savannas, hill tops are often left as prairie because their thinner soils hold less water. The main patch of prairie in Tandy is on top of the hill. Perhaps this is why.

It may be almost October, but the highs are still in the low 90s. The rain has returned, and a number of plants are putting on a second flush of flowers. Prickly pear fruits are bright red and ripe, reminding me of their alternate common name "cactus apple". Eryngo, snow-on-the-prairie, and false foxglove are all hitting their peak bloom. Others, like basket flower and white compass plant, have long since set their seed heads for the year.

Spiky, sticky white compass plant seed heads. 
Silphiums (i.e., compass plant, rosin weed etc) are unusual among composite flowers. Composite flowers, like sunflowers and asters, are distinguished by being composed of multiple smaller flowers bound together in a larger flower head. In a sunflower, the flowers that produce sunflower seeds are the 'disc' flowers, while the 'ray' flowers around the edges do not. This is the common arrangement for composites. However, silphiums set seeds from the 'rays'. If you harvest a seed head and break it apart in your hand it resembles an artichoke.

False foxglove, Agalinis spp. 
I also learned a new plant: false foxglove. False foxglove has flowers like a penstemon (or foxglove), but set along thin branching stalks with small leaves. I didn't notice the fringe of hairs along the edges of the petals until I looked at my pictures later. This widely distributed annual flower is in the Orobanchaceae family, and like other members of this family it is 'hemiparasitic' on the roots of other plants-- that is, it taps the roots of other plants to satisfy some of its nutritional needs. Perhaps this nutrient piracy could explain why the leaves seemed so undersized.

Eryngo, Eryngium leavenworthii, with small caterpillar
Eryngo is another flower whose details became more evident when I viewed the pictures later. I love the differences in tone between the indigo pollen and the royal purple flower. At first I mistook the late-season caterpillar for a bit of chaff or leaf matter.

Indeed, the insect life is still humming in this little prairie. On my way out, I noticed an oddly posed praying mantis near a clump of white fluff on a blazing star bloom. It didn't look like her egg sac to me- if anything, it looked like a small cocoon. I could be mistaken. I decided not to disturb her or the white mass and instead let them continue their preparations for the end of the growing season in peace.

Praying mantis, unIDd fluff, on blazing star

Monday, September 22, 2014

Bison yarn and royal purple

TNC's Niobrara herd. I helped sort them a couple times last year.
Every winter I knit socks, mittens and hats for my family, and somehow the process is even more enjoyable if I’m working with lovely materials.  I’m a sucker for beautiful yarns. This weekend I visited the Blackland Prairie Artisan and Fibre Faire up in Denison, Texas in search of new supplies. I arrived at Loy Park (home of the Grayson Frontier Village, behind a fence topped with a triple strand of barbed wire). There was also a lake, a bridge leading into the woods, and what looked like an old brick furnace. The surrounding land was mainly grazed. I found it picturesque.

The 'faire' itself was held in a large open shed with two horseshoe-shaped lines of booths on the interior facing the main entrance. It didn’t look that big, but it took me an hour to make a full circuit. When you fondle yarn and make small talk with half the craftspeople, I suppose the minutes add up. You could buy raw wool, yarns, baskets and other handicrafts. There were also artisans demoing the use of drop spindles, looms, and a great wheel.

One of my favorite displays was the natural yarn dying station. They had bright mustard orange from Bois d’Arc wood chips (also called Osage Orange), a fuchsia from prickly pear cochineal, and a natural indigo. The cochineal dye was most exciting to me. Similar to the ancient Greek ‘Tyrian’ or ‘Royal’ purple, it is derived from a crushed invertebrate. Instead of Tyrian purple’s Greek sea snail, cochineal originates in the body of minute scale insects living on the surface of Opuntia cacti. It has a Mayan and Aztec pedigree.

I also had the chance to reminisce about my days working with bison. I was delighted to discover a trailer and a booth for the Buffalo Wool Company, based out of small town just a little south of Fort Worth. I could not believe it was possible to buy bison yarn! Naturally, I bought myself a nice sized skein for a special project (TBD). I just love bison. I can’t help it. I'd argue they’re North America’s signature megafauna.

Buffalo Wool Company has moved their 35-bison herd to Goodnight, Texas since the metroplex has encroached upon the company’s original holdings in recent years. The company’s founder actually took some satisfaction in moving the herd. As some of you may know, the Texas legend Charlie Goodnight (for whom the town is named) is largely responsible for preventing the extinction of the southern bison. Lore has it that Charlie’s wife noticed the herd was much diminished and prevailed upon him to save the last few hundred. The descendants of those individuals now make up the core of the Caprock Canyons herd. For the Buffalo Wool Company, bringing their bison back to Goodnight was almost like coming an emotional full circle.
The Niobrara herd during fall round-up

Surprisingly, 35 bison are only good for about two skeins of yarn. Well, it’s surprising until you realize what one must go through to harvest the down from a bison. These are wild animals and they aren’t going to sit patiently while you give them a haircut. Fortunately for the wool gatherers, they aren’t going to sit still while you jab them in the rump with a vaccination needle either. Bison can carry brucellosis, which causes spontaneous abortion in cattle, and for this and other reasons they typically receive annual vaccinations. You have to round them up, get them in the corral, and then run them through a squeeze chute. You aim to keep them in the shoot for six seconds or less (to avoid excess strain on the beasts), and it is during these six seconds in the chute that you can shear a little strip of wool for the yarn. Apparently, they often come out with just a small racing stripe removed.

Other ways to harvest the wool include taking the brushes from street cleaners and setting them up vertically. The bison, eager to be rid of their winter coats, rub off their old hair on these convenient scratching posts. In addition to taking bits and bobs of fuzz from other bison ranchers, Buffalo Wool Company collects wool from the leathers discarded after a bison meat harvest. In this way, they are able to produce enough yarn to sell. I ended up buying a skein of a 50:50 bison/merino blend, though I was sorely tempted by the bison/silk. My yarn appears undyed. Perhaps I’ll go collect some cochineal to create my own all-American fiber. 

Saturday, September 13, 2014

Seasons change (in remembrance of seasons past…)

I liked how the cranes would arrange themselves in neat lines along the furrows

The seasons are shifting here in Texas. A cold front brought 3 days of drizzly overcast and highs in the low 70s. Considering that only last week we were topping out in the low 100s, this is quite a change. I was not ready for such an abrupt transition. Frankly, I was expecting to fight 90+ degree heat well into October. I may yet.

The birds know what's coming, though. We are in the peak of the southern hummingbird migration here in Fort Worth. I hung a feeder a few days ago, and the transient and ferociously hungry hummers found it just hours after it was filled.  I live in downtown Fort Worth and I can only imagine what the populations are like in less urban areas. 

I love the awkward way cranes land

On a related note, I was flipping through pictures stored on my camera this morning, and I re-discovered a series of images I took capturing this year's other major seasonal transition: instead of the casual moving-on of birds migrating to warmer climes for the winter, I snapped shots of sandhill cranes hurriedly re-fueling on the way to their summer breeding grounds.

Some of you may be aware that I moved to Texas from the state of Nebraska.  I spent most of my time on the Platte River in central Nebraska, the midway point and major pit-stop for the sandhill crane migration. With the conversion of much of the prairie to corn, sandhill cranes have responded to the shift in available calories and are now 95% corn-fed.

I took these pictures on a late March day in Nebraska. It was warm enough that I didn't need a heavy jacket, but cold enough that I shivered in the shade. My fingers went numb when I took them out of my gloves to operate my camera, and I had to alternate shooting and warming them under my armpits. I noticed this particular flock of cranes because I was out at a nearby state natural area, intent on taking advantage of the (relatively) warm weather. When I spotted a large flock of cranes picking at an adjacent cornfield, I saw my opportunity to sneak closer. I climbed up a berm on the property line and hid in the hedgerow like a creeper. I was quite lucky-- the birds didn't notice me, and they drifted closer as they fed. Contrary to peoples' expectations, if you want to see sandhill cranes, lurking in a fallow cornfield is a better bet than hiding in a blind at "zero dark thirty".
View from the bush (it was a red cedar)

Funny enough, these same birds winter near my new home in Texas. Interesting aside: on the Platte River, there was one famous whooping crane (already extremely rare birds, ~300 left in the wild) who would migrate with the sandhill cranes. Just now I was reading a TPWD article online, and they mentioned a single whooper who wintered with the sandhill cranes in Texas. I wonder if it's the same confused fellow.


Saturday, September 6, 2014

Little green bigfoot

Trust me, those are monk parakeets.
I had a surprising wildlife encounter on my office grounds yesterday. My office is located on an old army base, so we have a lot of open space historically used for… something military, with a small overlay of urban ecology. Much of the wide lawn is actually native plants. It is mowed within an inch of its life, but some fine specimens can still be found. The most interesting animal inhabitants I've seen are the roving flocks of green parrots.

Map of monk parakeet distribution, from Audubon site [2]
Called 'monk parakeets' (Myiopsitta monarchus), these birds have been introduced across the United States and Europe. The original colonists were escapees and 'intentional releases' by pet owners. Notable flocks occur in New York, Barcelona, and Chicago, among other places. Also: DFW. They are native to Argentina.

In their native range, monk parakeets prefer to nest in a tall tree surrounded by other tall trees [1]. They are the only nest-building parrot, and they are the only member of their genus. Their colonies build dense apartment complexes of twigs. Each couple has its own separate entrance and chamber, but they are attached to the larger structure.

Outside their land of origin, these are urban birds. In one study [1], 75% of nests were on electric power structures. They preferred to build nests on a high utility structures surrounded by high trees. Reed et al. hypothesized they chose the sites they did for protection from predators and abundance of twigs for nesting materials.

Also a monk parakeet. Really.
I doubt I would have believed my eyes when I spied the noisy flock of parrots chattering in a pecan grove if a colleague hadn't clued me into their periodic presence on grounds. I did my best to sneak up on them. However, the problem with colonial birds is they have a lot of watchmen.

I couldn't get very close, and I only had my iPhone camera, so my pictures are super crappy. They are so grainy and taken at such a distance, it looks like I was trying to document an elusive green bigfoot. Ah well. Better luck next time.

Lots of monk parakeets.


1. Reed, J. E., McCleery, R. A., Silvy, N. J., Smeins, F. E., & Brightsmith, D. J. (2014). Monk parakeet nest-site selection of electric utility structures in Texas.Landscape and Urban Planning129, 65-72.


Monday, September 1, 2014

An arid food forest

Down the driveway, north of Junction, TX
Last week I had the privilege of visiting the Native American Seed farm, located just north of Junction, TX.  NAS is on the western edge of the Texas hill country, where it meets with the Edwards plateau. Though it only took 4 hours to drive there, it was 260 miles and a world away.  The farm is not especially well marked due (in part) to the fact that it is not equipped to host drop-in visitors. I knew I was in the right place when I drove past a field labelled 'echinacea'.

This dung beetle was having a good morning
I waved to a man on a tractor doing field prep, and then I pulled off into the driveway behind a warehouse to await my hosts. As I got out of the car to get my self together, I noticed a black dung beetle rolling a small ball across the gravel driveway. Dung beetles are creatures with fascinating life ways and they are much loved by ecologists and ranchers alike. Dung beetles are major recyclers in grasslands. They are quite efficient at making the nutrients stored in old dung available to new grass. These insects suffer in urban areas due to a number of factors, but most surprisingly for one reason in particular: light pollution. Many dung beetles navigate by the milky way. If they can't see it they become totally disoriented and unable to find their way home.

Unlike many animals, it is the male dung beetles that are responsible for nest provisioning. Many dung beetles are poop specialists- they'll only eat the dung of a particular family of creatures. This is interesting in light of the fact that, near Junction Texas, escaped exotics from 'wildlife ranches' make up a large portion of the fauna. Axis deer, aoudad sheep, and wild hogs are major players. The NAS farm has both the exotic axis deer and the native white tails. Axis deer are bigger and keep their fawn-spotting for life. They have driven the white tails out of the river bottoms and onto the more marginal habitat of the uplands. We saw abundant axis deer when we toured the richer mesquite and prickly pear forests near the river. The white tails made themselves scarce.

Read more after the jump.