Armadillos to Ziziphus: David Hillis Talks About His New Book

With a state as big as Texas is, there is an extremely diverse ecology. From high altitude desert mountains in the west, to our vast coastline, to low-lying swamps in the east. Since most of the residents of the Lone Star State live in urban centers, sometimes it’s difficult to learn about the plants and animals that also call Texas home.

David Hillis, evolutionary biologist and the Director of the Biodiversity Center, has set out to help people learn about one of the most beloved and biodiverse areas of Texas: the Hill Country. His recent book Armadillos to Ziziphus, A Naturalist in the Texas Hill Country (University of Texas Press), is an approachable book that introduces a wide audience to the unique habitat and lifeforms that live here in Central Texas. It provides fascinating anecdotes and advice on how readers can encourage and promote biodiversity in their own “neck of the woods.”

David took some time to answer some questions about his book.

You mention that while an undergraduate in college, you spent a lot of time exploring the Hill Country. During these early years of your work, were there any specific species unique to Texas that really caught your interest? Perhaps it was a toad as you do have a self-professed affinity for them?

The first thing that caught my eye about the Hill Country were all the springs and spring-fed rivers, with crystal-clear water. So, I was drawn to a group of Groundwater Salamanders that are endemic to the area. I also started working on the ubiquitous Leopard Frogs, because they presented some fascinating problems and they were common and easily studied.

You talk about not only the ecological value but the human health value of biodiversity. With the increasing urbanization of Texas, do you see enough action being taken to remedy the disconnect people in the modern world often have with nature?

I think there is an increasing awareness, but unfortunately also diminishing opportunities for some to experience nature. We need to increase parks and wild areas that are open and accessible to the public. There are efforts to do that, but the rapidly increasing population of Texas is putting a lot of pressure on the public natural areas that exist.

Your book has many passages about water sources as amazing places to view microscopic life as well as listen to frog “choruses.” Are there places where people can view these things? Maybe good websites to sample toad and frog calls?

Texas Parks and Wildlife and the Biodiversity Center have collaborated to produce a web page that shows photos and calls of most of the species of frogs and toads of Texas: https://tpwd.texas.gov/huntwild/wild/wildlife_diversity/texas_nature_trackers/amphibian_watch/amphibian_species/

As for the microscopic and macroscopic life of vernal pools, one good place to look is in the pools at the top of Enchanted Rock in Llano County, in the Enchanted Rock State Natural Area. You need to go after a period of wet weather, as the pools dry up in dry weather.

You have been working on restoring many different ranches in Texas, and continue to expand when possible your Double Helix Ranch where you spend a lot of your time. What were some of the challenges Texas ranchers faced when you began this process, versus what you are seeing now due to climate change, water challenges, and the quickly-increasing Texas population?

The biggest issue is the rapid increase in price and demand for land, which is making fragmentation more of a problem. The climate is also becoming more variable, and in Central Texas, that has especially affected rainfall patterns. Now we get more droughts and floods, and the ones we get are more serious, compared to the past. In particular, we have endured some of the worst short-term droughts in recorded history since the turn of the millennium.

You mention collecting grasshopper populations off your fruit trees as a control method without the use of pesticides. How does one exactly collect these? I imagine this must be a tedious task.

It is actually very easy! I do it at night, by light of a flashlight, and the grasshoppers are easy to pick off the trees. Then I freeze bags of grasshoppers to feed to my chickens all winter long. They love them, and keep laying eggs, because they are still getting insects in their diet. It is a win–win for the fruit trees and the chickens!

How do the bats in the Eckert James River Bat Cave Preserve perform the emergence you compare to millions of airplanes leaving a single runway at once?

They space themselves using sonar echolocation. It is more complicated than it sounds, because they have to constantly modify the frequencies they produce to avoid interference from all the other signals. It is quite an amazing feat.

You mentioned that hummingbirds use spider silk for nest construction. How the heck do they get it?

They dismantle old spider webs, and re-use the silk from the web.

You shared a rather humorous story about an Eastern Hognose Snake and in its interesting self-defense display, managed to throw up its meal, a live toad. That was one lucky toad!

Yes, it was! I actually followed that toad and its distinct wounds, and it has lived for several more years since that happened. We call her Henrietta, and she comes back and perches on a prominent rock in our yard every year. I hope she comes back again this year…I am waiting on some spring rains to see.