Scientist plans to study lizard morphology in Boulder County

Many hikers and rock climbers might not even be aware of an interesting and important lizard species darting between rocks in Boulder County.

Even fewer know about the lizard’s unique coloration that Matt Rand has spent his life trying to understand. He explained his ongoing work with the lizards during a Thursday presentation to the Boulder County Parks and Open Space Advisory Committee.

The sceloporus lizard is common throughout Boulder County, Colorado and beyond. Formally known as the eastern fence lizard and southern prairie lizard, Rand — who has been studying these lizards since the ‘80s  — prefers the name red-lipped plateau lizard.

“Because that’s the coolest name ever,” he said.

Sub-species of these lizards are found throughout Colorado, but Rand focuses on the lizards found on the rocks in Boulder County. Locally, these male lizards have a lot of black and intense blue coloration on their throats and stomachs along with the red on their lips for which they are named.

“They stand on rocks and they hold their chin up high, or their head up high, and they display that coloration,” Rand said. “They’re highly territorial. They don’t tolerate other males.”

After starting his dissertation work, Rand discovered that the lizards actually come in “two flavors.” Some have orange or red lips, while others have yellow — which change the behavior the lizards have toward each other.

“Typically, in most populations I observed, orange males dominated yellow males,” he said.

What Rand will be studying for the next few years, however, is another morph of these lizards that he has only found in the Betasso Preserve in Boulder Canyon. This morph doesn’t have orange or yellow on its lips, just white, along with a higher amount of black covering up much of the blue on their stomachs.

“Over the years that I’ve been looking at these guys, it’s pretty clear that these differences are genetic,” Rand said. “What’s missing is the fact that I haven’t been able to show genetically the difference.”

Rand has found that the developmental pattern to get the coloring is the same, that individuals don’t change colors over years and it’s not hormonal. The colors are also not dietary pigments like scientists often observe in birds; they are biochemical in nature, according to Rand, so enzymes make those colors.

When Rand went out to observe lizards this year, he saw a big drop in lizards compared to a similar count in 2013. In 2012, Rand saw an average of 12 lizards daily, plus or minus seven, while in 2022 he observed an average of 4.5, plus or minus three.

He hypothesized that the cold, windy spring may have meant less lizard activity.

“I hope it’s due to the weather. I hope it’s not due to something else,” he said.

Rand also has found that in the Lyons area, specifically Hall Ranch Open Space, Rabbit Mountain and south Larimer, there is only the orange-lipped morph of lizards.

“That’s a curiosity in itself,” he said.

Rand is currently monitoring a marked population of lizards at Betasso Preserve to estimate reproductive success among the different color morphs. He’s also attempting to obtain a better picture of the different color morphs’ use of habitat types and features, as well as gain further knowledge of distribution of the lizards at these open space properties.

“You have to watch marked lizards for hours and hours to figure it out — and I don’t mind doing that,” Rand said.

Rand advised the committee that trailwork can have impacts on the lizards, who spend almost their entire lives on rocks. Feral cats can also harm lizard numbers.

He added that he’s crossing his fingers that next year the lizard populations will return to normal, but it’s hard to say if the population is declining without more data.