Southwestern Field Herpetology

Southwestern Field Herpetology


Based on some reports of speckled rattlesnakes seen on a trail in the Phoenix mountains in February, I set out to find the den they were staging from. This was found at the very end of March, which is pretty late, but in my experience speckleds can take awhile to stage out and distribute into the drainages and outcrops where they will spend the later Spring and early Summer. This guy was found right away within a few minutes of searching, presenting me with the debate that happens with early success … stay and observe, or go and find more?


See him there? Here’s a better angle.


I opted to stay, but he never came out. Eventually he seemed to notice me and withdraw, but not much. I decided to try and give him some water, and took a video.

I’m looking forward to watching this area later in the year!



Southern Pacific Rattlesnakes of San Diego

This is the fourth Southern Pacific Rattlesnake I’d ever seen, generously shown to us by the late Kent Van Soy in the San Diego area.

These snakes are generally regarded in the area as trash snakes, being a nuisance to boa hunters with bite-able fingers, but I think they’re amazing. I’ve always considered the Western Diamondback to be an example of the most adaptable of rattlesnake species, being found across a wide gamut of harsh environments and niches. These snakes, however, manage to thrive in well-developed urban areas, taking refuge in narrow drainage corridors without any access to open wild lands. In the right areas of Southern California, any patch of ground without pavement could be home to a healthy colony of SoPacs. One man’s trash snake is another’s treasure, as this one was to our group.

Crotalus helleri

… and this one:

Crotalus helleri


Desert Clouds North of Phoenix

One of the things I’ve learned to do in the years since I’ve paid attention to this blog, is to find dens. There’s a lot to it, but I’ve always been amazed at the diversity of circumstances that the common Western Diamondback Rattlesnake chooses to call home during the cooler months. In higher and rocky areas, there are a lot of options … but in the low Colorado river flats dominated by many cactus and few rocks, opportunities are few. This cholla patch is a good sign, meaning the ‘needle in a haystack’ approach I’ve taken to single out den sites is not far away.


Nearby, this is one of several diamondbacks I’ve been keeping an eye on in the Winter, taking advantage of space between a few rocks to enjoy the relatively warm air temperatures without the direct sun.

Western Diamondback Rattlesnake


Pipe Dangers

… not really. These little guys aren’t going to hurt anyone. But, every time I end up crawling through this pipe in North Central Phoenix on the way to tiger and speckled rattlesnakes, there’s at least one bat on the ceiling that won’t move until I’m right under it. Then … blam, it wakes up and freaks me out. I love bats, but less so when they’re directly flapping against your neck.

Also, right now I’m in Costa Rica for the second time! I kind of forgot to post to this blog for a couple of years reliably, and a lot has happened. I’m going to try to get through the hundreds of amazing experiences I’ve had in the meantime.




West Texas

Field herpers probably know this spot, or have driven past it a million times. On my first trip to West Texas, right on the border.


West Texas


Poison Ivy Magnet

After a long and hot hike in Southern Arizona with some friends, I finally spotted this Arizona Black Rattlesnake sitting in leaf litter … and some of those leaves were poison ivy. We got some good shots, and I paid the price. Worth it!Arizona Black Rattlesnake


City Boy

One of the best parts of living in Phoenix that animals like this exist right in the city. This old man is one of the gila monsters that I’ve seen numerous times right in the heart of the city, in the mountain parks.

Gila monster phoenix


Sandy Situations: Convergent Evolution for Life in the Desert

This post is part of #CrawliesConverge, a series of posts highlighting convergent evolution in reptiles and amphibians. More at RAMBIN, and on twitter.

In Arizona, we have a little desert rattlesnake that everyone has heard of, but not many people seem to know much about or have actually seen … or even know that we have them here. It’s the sidewinder (Crotalus cerastes), one of my favorite little rattlesnakes to find out here, and master of desert specialization.

They get the name in the same way that a lot of snakes get their names: bluntly labeled for something that they do. To move quickly over the hot sandy soil, they have evolved a particularly iconic behavior: sideways scooting over the sand by throwing a loop of their body forward, then pulling the rest alongside. This not only makes them the fastest rattlesnake1, but one that is able to move over hot ground that would otherwise kill it. They’re very common wherever they range, and are quite easy to find with just a little bit of effort – when you see one, it gives its identity away by the way it moves.

So, why do I hear at any education event where I’ve brought one to, “a sidewinder is a rattlesnake?! Wha!”? Everyone’s heard of a sidewinder, but a smaller portion of us know that they are a rattlesnake, or that they live here. They’re not at all misinformed. On the other side of the world, there is also a sidewinder that looks and acts very similar to our own little rattle-tailed variety.

It’s the Horned Viper (Cerastes cerastes), and it’s not even closely related to our sidewinder in the US. The split occurs up at the family level. Which means, as far as taxonomic categorization is concerned, they are as different as dogs and cats. They’re found in the middle east and parts of Northern Africa … a world away, so how similar could they possibly be? Here they are, side-by-side:

There’s more, too, than just movement. In pattern, these animals are remarkably similar.

Horned Viper:

Mojave Sidewinder


There’s more, too. Above each eye is a scale that has adapted to be a horn. It’s not exactly known why these exist; their function has several theories attached. One of which is that they could be flexible, or otherwise protect the eyes from blowing sand2. Regardless of cause, both of these snakes have evolved a similar structure to solve what is most likely a similar solution.

Horned Viper:
"Hornviper Cerastes cerastes" by H. Krisp - Own work. Licensed under CC BY 3.0 via Wikimedia Commons -

Sonoran Sidewinder:
Crotalus cerastes cercobombus


This similarity between animals on opposite ends of the Earth is one of my favorite, go-to examples of convergent evolution; perhaps because it comes up so often in day-to-day talking to people who are curious about snakes. Completely independently, they’ve found very similar solutions to common problems. If animal life on Earth were ‘rebooted’ and these snakes never existed, it’s extremely likely that snake-like animals would end up in similar places, where sand forces evolution to provide answers to life in challenging conditions. By procedure alone, the answer to how to live in the hot sand, if you’re a snake, is to look, act, and move like this.

Now, time to quit typing and get out to my favorite sidewinder-viewing spot before the sun sets! Check out the rest of the #CrawliesConverge posts on twitter.


2. Cohen A. C. & Meyers, B. C. 1970. A function of the horn in the sidewinder rattlesnake Crotalus cerastes, with comments on other horned snakes. Copeia 3, 574-5.


Arizona Glossy Snake from the Phoenix Area

Arizona Glossy Snake, Arizona elegans noctivaga



Speckled Rattlesnake from the White Tank Mountains

We saw this cool speck in a dark hole in the White Tank mountains, West of Phoenix. “Cool” is a relative term, which describes what this animal was trying to do on this particularly blazing day at the peak of summer hot and dry, like only Arizona knows how to do.




My Favorite Observation of 2014 – Crotalus lutosus Combat with my Leg

In the Spring I spent about a week at some C. lutosus den sites up North. I spent a couple of those days more or less standing in place for hours at a time, finding alternative uses for a snake hook (which is pretty much just a hiking stick at this point) as something to lean on.

Why was I standing there? I wanted to get combat photos. This den is a pretty big complex, with each group seeming to have one big male, several females, and a few other males hanging around. At one particular point, there were more, larger males, and females that moved between the smaller zones quite a bit. I figured this would be a good spot to find some conflict that would be more than just a big snake chasing a little one off. So I spent a lot of time just watching everything they did, standing more or less right in the group of rocks where they were, as still as possible. It’s actually kind of amazing how entertaining staring at a stationary pile of snakes is if you’re interested.

Anyway, I saw a lot of cool things that week, took a lot of photos, and I did get some combat (and video), and more. The best part to me, was when the big male in this zone chased a similar-sized one to rocks just below my feet. The defeated snake took off (I saw him later in another area 20′ or so away). The victor went to court his pile of females. In the middle of this, I had to shift my weight, and was spotted by him. He came out at me with his head raised, attempting combat with my leg.

I moved my hiking stick out front in case there was contact (I didn’t touch him of course), but there was none. He would stand up and do his thing around the rocks at my feet. When it got to where he actually flopped down ONTO one of my boots that I decided to step back (after he’d slid off). As soon as I left, he went right over to court with the females.

In the next few days, I could reinitiate this behavior with him any time by approaching and standing in that spot, and moving gently moving grass near his rock. More amazingly, I reproduced this with another group days later (to a lesser degree, but I was retreating much sooner). I was able to show this second instance to Kris Haas, who’d flown up to join me at this point.

To anyone worrying that I’ve interacted with a group in such a sensitive situation – this wasn’t my intention. I’ve already been watching this group for a few days at this point, so I didn’t miss the in situ observations that could be disrupted by my being there. I also was never buzzed or even tongue flicked. I take great care to not disturb anything.

Here are some photos, which were hard to get since this was happening right below me, and I had a 100mm prime on. Once he got closer, I couldn’t get anything at all.






Red Diamond Rattlesnake – Up Close