Yesterday (April 25, 2024), I was slowly walking in the sage brush desert of Southwestern Colorado. This was at about 7000 feet of elevation. I was waiting for my companions to get their horses ready, and was looking to see if I could find any creatures to photograph. I had nearly given up when I saw a Horned Lizard move away…and there was another, smaller, lizard riding on its back. The smaller lizard was biting the neck of the larger lizard. The larger lizard squirmed and struggled a bit, and the smaller lizard fell off. The larger lizard ran a few feet away, with the small lizard slowly following.
These were Short-Horned Lizards, and the male was attempting to mate with the female. She was the larger, gray, lizard in the photo above, and the male was the smaller. I’d guess the female’s body was about 3.5″ long, and the male’s was perhaps 1.5″ long.
The female looked a bit emaciated to me, while the male looked plump and healthy.
As I stood watching them, I noticed some commotion in the dried grass behind the male lizard, perhaps three feet away. It was a a group of three more male Horned lizards thrashing around, wrestling and biting at each other. I unfortunately didn’t manage to get photos of them – the dried vegetation was too dense.
I watched the female and male lizards for a few more minutes. The male crawled up to the female, and started biting at her legs and back. He finally bit and held on to the fold of skin on the side of her neck again.
Since the horses were ready to go and I didn’t want to disturb the lizards further, I left the lizards to their own devices.
My companions rode their horses and I hiked along with them. It was a sunny day, perhaps 65 degrees F. I saw three more Short-horned Lizards as we traveled. They would scurry out of the dust of the trail as we approached. All were tan-colored, smaller lizards – probably males.
We were out for perhaps an hour and a half. As we neared the the trailers, we saw what looked like the same female and male lizard, mating and struggling. They were about 30 meters away from where I’d seen them previously.
As before, the female would alternately carry and drag the male along as he bit down on the skin of her neck.
His tail would writhe and wiggle every now and then, but I didn’t see her make an obvious effort to move her vent closer to him. From what I’ve been reading, Short-horned Lizards typically breed from May through June. These lizards were a bit early – perhaps the female had only recently emerged, and wasn’t receptive to mating yet? She certainly looked emaciated.
Sometimes he would release his bite, and he’d move a few inches away from from her. He was visibly panting. Then he’d come back to her. He’d start by biting her side or legs, but eventually move back to her neck. All of these photos show him on the right side of her, but he’d also bite the left side of her neck.
In a lot of other species of Horned Lizard, the male bites and holds the female’s horn during mating. But in Short-horned Lizards, the male bites and holds the skin on the side of the female’s neck, the ‘nuchal fold’. Presumably because her horns are too short. They are, after all, called “Short-horned Lizards”.
In most Horned Lizard species, he female lays eggs. But in these Short-horned Lizards, the female gives birth to live young a few months after mating, hopefully during the time of the Summer Monsoons. Perhaps this live-bearing is an adaptation that allows them to live at higher elevations and colder latitudes than the other species of Horned Lizards.
So…all of this was a pretty cool thing to see. Watching Horned Lizards is usually similar to watching Buddha meditate…they sit very still except gulp down and an ant now and then…then lapse back into their seeming-trance. It was pretty interesting to see this other side of their lives.
Sources:
Hodges, Wendy L. (2009). Greater short-horned lizard (Phrynosoma hernandesi) section in Jones, Lawrence L.C and Lovich, Robert F. Lizards of the American Southwest: A Photographic Field Guide. Rio Nuevo Publishers, Tucson, Arizona; Illustrated edition (September 8, 2009). 568 pages. ISBN 1933855355.
Sherbrooke, Wade C. 2003. Introduction to Horned Lizards of North America. University of California Press (May 8, 2003). 191 pages. ISBN 0520228278.
Wikipedia’s Greater short-horned lizard entry.
