The Rattlers of Suizo, AZ

Last weekend I took a night trip out with the Suizo Project. The project’s hard working leaders use radio telemetry to record the movements and key life history traits of rattlesnakes living in the Suizo Mountains in Pinal County, Arizona, which is in the heart of the Sonoran Desert. You can view their Facebook page for project updates here. This was beautiful country and the time of year couldn’t be more perfect: the hot and humid monsoon which plagues the region every summer has officially ended (and so have the days which reach 100 degrees Fahrenheit by 10am and 108 by 3pm). While it still gets hot  in the Valley of the Sun near Phoenix (100+, occasionally but not for long), down south in the mountainous Suizo area closer to Tucson (close to 3000 feet at the site I was told) it is simply lovely. The moon was a few days after full, and through the clear and dry desert sky the landscape glowed in a cool blue nightlight. Throughout the evening the temperatures stayed in the 70s and it was the type of night you spend on top of, but not inside, your sleeping bag.

After sundown we embarked on a five hour trek, meaning I followed the knowledgable and experienced guys around the desert and completely took advantage of their skill and expertise in order to learn a lot of things and take a few pictures (I’m not ashamed). Let me just say that in academia, I meet a lot of folks who know a lot about a lot of things but these. Guys. Know. Rattlesnakes. They are experts who can school anyone in the natural history of these incredibly fascinating species – the seasonality of their movements, their food preferences, their mating strategies, their evolution and the environment in which they live.

Some gratuitous musing:

Throughout the 20th century and into today, biology has evolved into ever more specific sub-disciplines, each noble in their own right yet many increasingly cordoned into a sterile laboratory or anonymous computer server, removed from the true natural world. I think the subject of natural history still has its place as a philosophy, a method and appreciation of understanding how the world works. It was after all what inspired me to become an evolutionary biologist.

Anyway, here are some great rattlesnake pictures:

Black-tailed rattlesnake (Crotalus molossus)

Black-tailed rattlesnake (Crotalus molossus). Very docile creature distinguishable by its relatively large, roundish triangular-shaped head.

Longhorn cactus beetle

Here’s a nice closeup of a  longhorn cactus beetle.

Funnel web spider

A nocturnal funnel web spider, waiting for its next meal.

Tiger rattlesnake (Crotalus tigris)

A female tiger rattlesnake (Crotalus tigris). Note the cactus spines lodged into the scales on her face and torso (yes, snakes have a torso, there’s more to them than a head and a tail). Despite these difficulties, she was in a rather accommodating mood.

Nice shot of the same tiger rattler from above, to highlight its beautiful markings

Nice shot of the same tiger rattler from above, to highlight its beautiful markings

Western Diamond-backed Rattlesnake (Crotalus atrox). I crossed the continent hoping to see these guys in their natural habitat, and I was ecstatic to find him. While beautiful and wary of humans, it is extremely venomous (even more so than the other rattlers).

Western Diamond-backed Rattlesnake (Crotalus atrox). I crossed the continent hoping to see these guys in their natural habitat, and I was ecstatic to see this one. While beautiful and wary of humans, it is extremely venomous (even more so than the other rattlers).

UPDATE [9/27/2013]: I received a response from Marty of the Suizo Project team, who corrected my summation of the relative potencies of rattlesnake venom:

…”extremely venomous, (even more so than other rattlers)” wouldn’t be how I’d describe their venom. They are more venomous, which can be measured in toxicity or volume, than many species of rattlesnakes in terms of volume but few when using LD50 values as a proxy of toxicity. Tiger rattlesnakes, on the other hand, have the most toxic rattlesnake venom but have a small venom yield. Tigers don’t bite people due to their habits and habitat, and relatively small geographic range, while diamondbacks have a comparatively large geographic range, often in close association with people, and are responsible for more human deaths in the U.S. than any other rattlesnake species. It could be said diamondbacks are ‘more deadly’ than other U.S. rattlesnakes…not as in ‘deadly’ in a comparison of toxicity but literally are more deadly because they bite and kill more people – the true measure of deadly!

Thanks for the important distinction, Marty. I wouldn’t want to give diamondbacks a bad name, although we must admit that sadly it is a lost cause…


A Desert Tortoise Field Trip

It’s the hottest time of year in the Valley of the Sun, and the unavoidable and unrelenting desert summer heat prevents newcomers such as me and my family from fully exploring our new beautiful surroundings. This is a sad fact, although the reality is that our lives are so upended by the move that we have little room for field trips – it will be better come springtime when (1) we are more settled and (2) daily temperatures will be cooler and the desert will be blooming and full of life. My wife and daughter escaped the heat this week to visit family in Portland, OR – a place with almost opposite climatic conditions from here. The brief northwestern Oregonian summer with its dry warm days and blue blue skies are hard to beat. So I am glad they have a chance to have some fun in the sun without having to worry about their health, like they would here.

Meanwhile, in the Phoenix area I have been relegated to air-conditioned indoor activities at the lab, office and home. Pleasingly, I received an invitation from one of my new colleagues who studies tortoises to join the Arizona Fish and Wildlife Turtle Management Team as a volunteer on a tortoise-monitoring trip. Since I am part of a group that is planning on sequencing the Desert Tortoise genome for its conservation, I thought it was a serendipitous opportunity to actually meet one of our possible study organisms. We were to meet the team at the Sugarloaf Mountain Area in the Tonto National Forest, about one hour northeast of downtown Phoenix. In the summer, these excursion need to start early – both humans and animals need to avoid the midday heat – so I picked my colleague up at 4:30am. The habitat was beautiful. It’s amazing that these sprawling desert landscapes contain large desert reptiles!


The Sugarloaf Mountain area in Tonto National Forest. There are tortoises wandering around this landscape, and we were searching for both tagged and un-tagged individuals.


Here comes one now!


Close-up of a desert tortoise (Gopherus morafkai)

The team did manage to find tortoises but I forget the exact number. I was much more of a spectator on this trip, as it was my first excursion into the desert since we moved our here, and my field search image is not attuned to tortoises. So while these photos are my own, I had to rely on other more experienced folks to actually find the animals. They really just look like desert rocks, and they freeze when they see a person.

The extremely competent members of the turtle team were taking vital measurements of each tortoise as part of a long-term study tracking the growth and movements of desert tortoises that live in this part of the Sonoran Desert.ImageBeing out in the desert afforded an opportunity to see other reptiles, of course. Here are some pictures of an earless lizard (genus Holbrookia). During one rest point for the team, this individual was perched on a nearby rock giving us the business – which in lizard language consists of nasty looks and push-ups.Image


You think you can take me?

Out of all the reptiles, you have to admire the chutzpah of some lizards. Upon being approached by humans, tortoises hide in their shells, snakes slither silently away, alligators dash messily to the water’s safety… but many species of lizards give humans displays of dominance almost right up until the last minute. Then they run away of course. But for the first few seconds it always seems like the little lizards really are sizing you up and thinking they can take you on.


Believe it or not, the tortoises love this rocky terrain!