A Texas Ecology Lesson

161228_tx-heard-nature-sanctuary_7840acsEven in winter, the Blackland prairie habitat at the Heard Sanctuary in Texas was beautiful. Sunlight painted the grasses and plants with glowing shades of amber, russet and pale cream. A bird box awaited the arrival of new life.

I wasn’t expecting an ecology lesson when I wandered through the Heard Sanctuary. I was thinking about the variety of habitats and plant communities that I was seeing. I was also wondering where the critters were. But I soon realized that all the elements of a complex ecosystem were observable here, hiding in plain sight.

ECOSYSTEM (noun): a community of living organisms in conjunction with the nonliving components of their environment (things like air, water and mineral soil), interacting as a system. (Wikipedia)

A habitat is the natural environment for an organism. Add a variety of plants and animals, make it interconnected and self-sustaining, and now you’ve got an ecosystem!

An ecosystem is self-sufficient and cyclical; its nutrients go through a series of changes that transport them around the ecosystem in an unending web. Ecosystems need abiotic matter, producers and consumers, scavengers and decomposers. All of these were in evidence on my walk through the Heard Sanctuary.

161228_tx-heard-nature-sanctuary_8157aThis is the black soil of the Blackland Prairie. Soil, sediment and organic matter form the abiotic component of an ecosystem. Here the soil is an alkaline clay of chalk, limestone and shale. In dry weather, large deep cracks form in its surface. All the cycles of life – the carbon, nitrogen, oxygen, water cycles and more – start with the soil and come back to the soil. Abiotic matter, check.

161228_tx-heard-nature-sanctuary_7755acsGrowing in that rich dark soil were plants. Pretty plants…

161228_tx-heard-nature-sanctuary_7759acs… and strange plants. This one has winged stems. Plants are the producers of the ecosystem, taking nutrients from the soil and energy from the sun to grow and reproduce. Their seeds, fruit, stems and leaves become food for the animals. Producers, check.

161228_tx-heard-nature-sanctuary_7538acsWalking along the trail through the woodlands, I heard the twitters of small birds – chickadees, nuthatches, a cardinal. While searching in vain for them, the nubby texture of this tree caught my eye. That big hole looked just right for an owl… but alas, no one was home.

161228_tx-heard-nature-sanctuary_8112aThese are galls, or they may be burls. The two growths are similar, and there are so many conflicting definitions online that I couldn’t sort out the difference. Insects, bacteria or fungi get under the tree’s skin, and an abnormal swelling of plant tissues forms around the invader. These growths are the result.

Most galls are small and appear on leaves or twigs, but they can be large and woody. Burls seem to be exclusively woody. Inside a burl, the rings of the wood twist into lovely shapes that are prized by woodworkers for their beauty.

161228_tx-heard-nature-sanctuary_8117acsI thought the outside was beautiful, too.


In this season, my wildflower guide was not a lot of help. Without flowers on the plants, I couldn’t identify much along the trail.

But I could admire everything! Except critters. So few critters to admire…







Then I came to the swamp, and suddenly there were animals everywhere.

Waterfowl swam placidly past. Coots. Mallards. A Northern Shoveler.

161228_tx-heard-nature-sanctuary_7986acsAnd turtles. Lots of turtles, basking in the 82° sunshine. There was plenty of plant material in the swamp for herbivores like turtles and ducks. Primary consumers, check.

161228_tx-heard-nature-sanctuary_7546acsOh, cool! Snakes!

Yes, that’s actually what I thought when I saw this sign. I’ve never seen either a copperhead or a cottonmouth. I was hoping to see one or both, though preferably at a safe distance. Not this day, though.

161228_tx-heard-nature-sanctuary_7802acsI found some droppings on the boardwalk. Why, oh why, you might ask. Why was I interested in this?

Because there was fur and bone in them, the calling card of something carnivorous like a fox or coyote. I never saw the animals themselves. For evidence of this component of the Heard ecosystem, a little scat had to do. Secondary consumers, check.

161228_tx-heard-nature-sanctuary_7785acsWheeling over the prairie, a Turkey Vulture. Even though I see them all the time back East, they somehow seemed appropriate in this dry environment. To our eyes, vultures are ugly birds with an ugly lifestyle – they eat dead animals. Scavengers like vultures play a really important role in consuming and passing on the nutrients that would otherwise remain locked inside an animal’s body after it dies. Scavengers, check.

161228_tx-heard-nature-sanctuary_7541acsNearby, a bracket fungus clung to another tree like the bookshelf of a woodland elf.

161228_tx-heard-nature-sanctuary_8012acsFungi are neither plant nor animal; they make up their own kingdom and play their own part in an ecosystem. Fungi’s role is to decompose organic matter.

The portion we see, the mushroom, is the fruiting body of the fungus.

Decomposers, check.

161228_tx-heard-nature-sanctuary_7915acsThe variety of plants in the swamp, cedar brake and prairie of the Heard Sanctuary was a marvel to behold. Studying it and photographing it kept me busy and happy on a warm December day.

161228_tx-heard-nature-sanctuary_7959acsAnimal life was less obvious. Turtles sunned themselves on logs, while birds sang in the trees. Scat revealed the presence of a carnivore, but the critters themselves were tucked away out of sight.

Soil, plants and animals; swamp, woodland and prairie. All the building blocks of an ecosystem were there in the Heard Sanctuary for me to see if I looked hard enough. A walking ecology lesson!

Lone Star Habitat

2016-12-28_tx-heard-nature-sanctuary-pan-1acsI’ve been thinking a lot about the word “habitat.” My friends and I throw the term around a lot. We talk about pristine or disturbed habitat; interesting, unusual or downright odd habitat; preserving habitat and restoring habitat.

What the heck are we talking about?

The Heard Natural Science Museum and Wildlife Sanctuary in McKinney, Texas showcases a variety of habitats, from wetlands and forest to prairie. On a recent visit, I took a walk that wound through several different habitats, three of which were unlike anything I see back East. Along the way, I started to muse about the meaning of habitat.

HABITAT (noun): the natural environment of an organism; place that is natural for the life and growth of an organism. (Dictionary.com)

It’s the place an animal or plant lives. It’s comprised of everything an organism, or a population of organisms, needs to survive, from soil, moisture and light to food and shelter. Habitats range from a large area like a forest to a small site, such as the inside of a rotten log.

My friends and I use the term in a wider, more colloquial way to refer to a geographical area of varying size, where the soil, geology and plant communities are fairly uniform. Technically, that’s a “biotope”, but the terms are so similar that we say “habitat.”

161228_tx-heard-nature-sanctuary_7643aDallas lies in the Texas Blackland prairie region. Before much of the land was converted to agriculture and residential use, grassland, oakland and savanna habitats once covered the area.

At the Heard Sanctuary, the trail wound through remnants of Blackland prairie. A type of grassland, prairies typically have deep fertile soil, on which grasses and wildflowers grow. Trees and shrubs may be present, but cover no more than 10% of the area. For centuries, animals such as bison, pronghorn and deer, as well as wildfires, kept woody plants and trees at bay and preserved the land as prairie.

161228_tx-heard-nature-sanctuary_8179aGrasses found in the prairie include big and little bluestem and Indian grass. In winter, golden browns, russets and tans adorn the land. In the growing months, these hillsides are ablaze in wildflowers.

161228_tx-heard-nature-sanctuary_7931acsAt the Heard Sanctuary, I encountered a swamp for the first time. They call it a wetland, but it’s a swamp. “Wetland” is a term that encompasses any land area saturated with water at some time of the year. Bogs, marshes and swamps are all wetlands, but a bog is not a marsh and a marsh is not a swamp. Marshes, like those at John Heinz NWR near home, are dominated by soft-stemmed herbaceous plants and grasses.

161228_tx-heard-nature-sanctuary_7926acsSwamps like this are dominated by woody plants, aka trees.

The swamp here is ephemeral, meaning it is not flooded the whole year. In the summer, it dries up. During the dry period, annual plants sprout.

161228_tx-heard-nature-sanctuary_7956acsThen the autumn rains come, and the plants die. Their seeds and leaves become an important source of food for the wetland visitors and inhabitants. The swamp is again a watery wonderland.

161228_tx-heard-nature-sanctuary_8015acsFurther along the trail was another interesting habitat, the Cedar Brake. I wondered what a “brake” was. From what I’ve been able to find, it’s a tangle of dense brush and briars. So the cedar brake was a thick cedar grove with a thick brushy understory?

161228_tx-heard-nature-sanctuary_8022aLife is not so simple. As you can see, there was almost no understory to this cedar brake. Lots of trees, yes, but no brush. Deep in the woods, the trees were bare of foliage for most of their length.

161228_tx-heard-nature-sanctuary_8111acsOnly when I looked to the sky did I see the greenery.

161228_tx-heard-nature-sanctuary_8083acsAbout those trees… They may be called “cedars”, but they are not true cedars. Instead, they are junipers in the Cypress family.

Junipers are evergreen trees or shrubs with small scale-like leaves and cones surrounded by a fleshy covering that looks like a berry.

Junipers often occur in oak-juniper woodlands in Texas, but here it was a monoculture of cedar trees.

161228_tx-heard-nature-sanctuary_8060acsExactly which juniper tree remains a mystery, to me at least. Identifying junipers is very difficult, even for experts.


Possibly Eastern redcedar, Juniperus virginia, which usually has a single trunk.

Ashe juniper, Juniperus ashei, known as post cedar or Texas cedar, is common in Texas, but usually has multiple stems and is shorter.

Both have blue seed cones, and the two species hybridize.

161228_tx-heard-nature-sanctuary_7537aEvery region has its own types of habitat, and exploring different regions of the country is a great way to get to experience distinctive environments. When I am in Texas, I always seek out natural places that have something new to show me. With a wonderful variety of habitats, the Heard Sanctuary did not let me down!