CHS Blog

Life, Change and Philopatry on Bearpaw Shale

April 12, 2020
Nicholas A. Cairns
An adult female Greater Short-horned Lizard that became ingrained in my family’s life. Photographed here just after consuming a grasshopper, note the “tobacco juice” on her lower jaw.

This is not a post about research. This is a post about a single animal: an adult female Greater Short-horned Lizard (Phrynosoma hernandesi) that has been a part of my family’s weekly routine for years. The first time I saw this lizard was in August of 2015 on a brief visit home to Val Marie, SK for the nuptials of some dear friends. The lizard was a different colour than any other Greater Short-horned Lizard I had ever seen; dark sides with a light, almost rose-coloured dorsal swath that runs from her snout to the end of her tail. And there she was, right beside the trail.

An adult female Greater Short-horned Lizard with diagnostic dark sides and orange/rose tinted “horns” and dorsal line. Of hundreds I have observed I had never seen any other lizard in Grassland National Park that looked this.

In 2013-2014, Grasslands National Park began trail construction in an area popular with hikers to improve accessibility and avoid trail braiding. I had been lizard- and snake-watching there since 2004 and was opposed to the construction. I generally oppose development on unbroken prairie but my opposition was more acute as I had oversized and perhaps undue sense of ownership over that area. I had also never had issues with accessing any place I wanted to go.

Then I had children and my understanding of the utility of these land use compromises changed. My kids have partaken in research and recreational herpetological pursuits since they were weeks old. Crammed into waders, watching undergrads learn to process frogs or watching a toad on the front lawn, herps became part of the life we shared. This was true in Kingston where I was in graduate school. There, the climate is mild and you can have a child out for long portions of a day, but back home in southwest Saskatchewan the intense heat, rugged terrain and now and then a surprise rattlesnake requires caution and reduced exposure. This is the environment the Greater Short-horned Lizard lives in and it usually takes hours to find one. To see one sitting beside the trail while pushing a stroller was a treat; when we first saw her in 2015 I noted her location and we continued our hike.

Typical Greater Short-horned Lizard habitat in Grasslands National Park with eroded Bearpaw Shale and a diverse assemblage of grasses and forbs
More habitat with a different more typically coloured female Greater Short-horned Lizard we watched on our regular hikes.

My family walked this area as often as we could and became more aware of the individual lizards and their regular haunts, including this dark-sided individual. We saw her consistently in a southeast-facing patch of hardpan with an ant trail, sparse grass and a few forbs. We continued to see her in 2016; that year we found 4 neonates that, based on geographic location, we presumably were hers. By this point my eldest child, mostly by self propulsion, could walk the whole trail and became better at finding lizards than me. We started waiting to have our snack on the trail by the lizard’s little patch so we could watch her while we ate. As long as we were a few meters away, she would go about her business, eating, pooping (they poop a lot for lizards) and observing her little corner of the world.

The observant gaze of the dark-sided female that became such a constant in my family’s life

In 2017, we got to watch her whole year in detail. We found her arriving to her spot in late May surrounded by blooming Missouri milk-vetch. Then being so gravid she could barely move in late July, followed by eating like a fiend in August after giving birth, and disappearing in September. We took snowshoes and a sled to see her spot in the winter.

In 2018 she again showed up at the end of May. I think she comes from a burrow where two Bullsnakes overwinter, but I can’t prove it. She is a good size, but not huge, at around 70 mm snout to vent (head and body but excluding the tail) and ~16 g. Males come and go from her area but we didn’t observe any mating, but by July she again nearly doubled her mass with a litter of neonates.

Left: The dark-sided female while heavily gravid (pregnant) in 2017, we know that she had at least three litters; Right: A neonate/new-born Greater Short-horned Lizard one of four that we saw in 2017 within the confines of the dark-sided female’s summer range though it is likely there were more that we did not see.

Then in 2019 we didn’t see her. I went away to work and when I came back, we didn’t see her on our walks. We had never missed her for two walks in a row during the active season, and I don’t think we’ll see her again. We had a harsh start to winter in 2018 with deep cold before any notable snow fall and I fear that ended her life. However, as I was preparing this little note, my family and I walked out to her spot. There we found a smaller female with the same dark flanks and rosy dorsal stripe. I hope and assume it is one of her offspring.

I learned so much about the seasonal/daily patterns and life history of these lizards by watching this one individual. I’ve seen her in air temperatures as low as 6° C and as high 41° C and ground temps even more expansive, but she usually got active when the ground was 27° C. Despite eating mostly ants, I’ve seen her eat prey as large Bandwing Grasshoppers. The most impressive and enduring thing about this lizard was her philopatry (tendency to reuse the same area year after year); every time I wanted to see a lizard, be it for natural history or therapeutic reasons, she was there in her 4X2 m patch of badlands. There my family and I could observe little snapshots of her life. In a profession where I have strived for quantifiable data, I have often missed the anecdotal. To have had the privilege to observe one individual for dozens of hours over years, learning her habits and the context for all the numeric facets of her life, was a joy—especially to be able to share that experience with my family. I will genuinely miss this lizard, more so than any other wild animal I have ever observed.