Essays

Moseying: Exploring the Natural World

Midland’s Urban Forest – a dynamic ecosystem always changing
October 31, 2007

“How did the squirrels get to Midland? When did they get here?” On Thursday October 25th, I was asked to answer these questions and more at the Senior Services Center. The squirrels are not the only thing that have come to town to “pester” us!

At the Sibley Nature Center we base our educational efforts on the framework of the eight major habitats of the Llano Estacado. We believe that all of us Llaneros should be conversant with the stories of the ecology and history of our home. We want everyone to love our “wild and woolly landscape!” People are often surprised when they learn that “The Urban Forest” is a dynamic ecosystem (albeit artificial). Do you know the other 7 habitats of the region? (Visit the habitats section of this website and you will discover the answer and much much more!)

We plant lawns, trees, and gardens in town. By that very act we invite other creatures into our living space. Mixed in with the plant material are seeds of unwanted plants, too. As the region was settled, emigrants on trains and in covered wagons often brought garden plants with them. The first creature to ride along was the decollate snail (photo at right). I am sure you have seen them – for every last one of them looks like their long shell has broken. It was mentioned as being present at Fort Concho, back in the 1880s!

Some of our weeds arrived then, too. Johnson grass, a pest for today’s farmers, was purposefully planted to feed the mules that pulled the fresnos that moved dirt for the railroad. Bermuda grass was brought along with the settlers and began its long history of adapting to our environment – and now a hardy strain grows wild in barditches, old farm fields and as an unwanted addition to flowerbeds. Rescue grass (now called winter rye by most folks) was also brought by ranchers to provide winter-feed for their stock.

The big dog-day cicadas were the next creatures to establish a thriving population in West Texas towns. In the 1920s the United States government sent a botanist to China and Russia to identify a tree that would grow on the Great Plains, and the Siberian Elm became the candidate for the first “tree-giveaway” program. Thousands were germinated in nurseries within the native range of the dog-day cicada, and when the trees were sent west on trains, the cicada nymphs within the soil of the root balls came along. By the 1960s a person could hardly hear a normal conversation under a Siberian Elm because of the raucous singing of the cicadas (locusts as they are commonly called.)

As the Siberian Elms grew, the small Inca doves (with reddish underwings) moved in from the south. Mississippi Kites came to West Texas then from the east in the late 1950s. The beautiful silver hawks specialize in cicadas and often nested along golf courses. The Kites defend their nests by dive-bombing passerbys, so golfers often had stories for the 19th hole.

In the 1970s we began planting live oaks and pecans. Within a few years, blue jays from central Texas began appearing in the winter to harvest the acorns, and by 1980 were nesting in Midland. Great-tailed grackles (photo at left) first arrived in 1980, and by 1985 had begun nesting. Grackles were originally only found in coastal swamps, but much of that habitat was destroyed for beachfront condos, so the grackles discovered sewage treatment plants and spread over the entire United States. Like the blue jays, the grackles eat the eggs of other birds, and sometimes even eat the nestlings. The grackles go one step further, and the larger nestlings too large to swallow are tossed on the ground to slowly die (unless a homeowner rescues them and returns them to the nest or calls rehabber Bebe MaCasland in Big Spring.)

By 1980 the large garden snail had arrived on potted plants from California. In the mid-1980s Mediterranean geckos and green anoles disembarked from other shipments of nursery stock coming from Houston or Florida. Several other animals have increased their range as a result of the screwworm eradication efforts of the 1970s, so raccoons and opossums came up the draws to town from the east. Mule deer and white-tailed deer (and their predator – mountain lion) moved into the more rural areas along Monahans and Midland Draw south and east of Midland. Porcupines came from the west by the 1960s, after mesquite had finished spreading out of the draws and covering the south Llano Estacado rangeland.

The squirrels arrived from central Texas on big tractor-trailer rigs. When the trees are dug in February and March, the branches were wrabbed with webbing. Mama squirrel has newborns in her nest, so she does not leave, even when hauled hundreds of miles. When the tree is planted and the webbing is cut, the squirrels are set free. This happened often enough that local breeding became commonplace.

Many species of weeds have become part of the urban forest. Alley mustard germinates on bare ground in the fall and blooms by February. Henbit shows off its tiny purple blooms in lawns in March. Nutgrass arrived when grass sod became big business – and unfortunately the sod industry is also to blame for the imported fire ants (that can only live in West Texas where we water.) Dandelions also increased as a result of sod. Potted plants brought in the horrible knotroot bristlegrass, whose seedheads attach to pets and their owner’s socks if brushed against.

Annual bluegrass loves a shrub-bed or flowerbed without mulch. The transported liveoaks also brought in poison ivy and greenbriar to landscapes. The redoaks brought in mistletoe, which the berry-eating birds have spread even further. False poinsetta became a common pest by the 1980s. Chaff-flower became a pest in parks and schoolyards. Yellow and white sweetclover, yellow burclover, and white clover all arrived in West Texas over the years, the seeds transported in the treads of tires.

Our roadsides have also vastly changed in the last thirty years. In the fall the red seedheads of King Ranch bluestem line most of our highways. In the 1970s Maltese thistle spread along every roadside from San Angelo to El Paso. Engelmann daisy lines the highways with yellow flowers in May. The African Lehmann’s lovegrass, planted by the highway department and pipeline companies for revegetating soils bared by construction, has now spread far into the rangeland of West Texas. European bindweed seeds, as a contaminant in birdseed and in grain seed sacks now line many highways, especially to our north between Lamesa and Lubbock and further north. Seepwillow seeds blew in from the south to many of our playas and draws, and now are appearing in people’s yards.

It is amazing how quickly plants and animals colonize new “niches.” All plants and animals produce more seeds or babies than can survive, so if there is “new” habitat created, it will be found, with or without our help. “Lost cities” like Chichen Itza and Macchu Picchu became wilderness after being abandoned… and so would Midland!