The blue-grey eyes of a Southwestern Speckled Rattlesnake stand out against its red and grey body. This is a typical look for the species as they are found in rocky areas of central Phoenix. This snake carries a small passive radio transmitter that helps us learn about its life in an urban park.
A pregnant Southwestern Speckled Rattlesnake out on a wet morning, coiled to maximize rain capture. A surprise rain got about every rattlesnake in the area on the surface for the day, in various forms of this pose. Hydrophobic scales help collect drops of rain, which the snake can then drink directly from its skin, as she is doing here.
A rattlesnake that looks like a rock. This Southwestern Speckled Rattlesnake was found in central Arizona in an area of rusty granite and quartz. The resulting cryptic pattern is just as colorful, including speckled grey blue eyes. Though it is brightly colored, these snakes can be very difficult to see in context.
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A Southwestern Speckled Rattlesnake in ambush on a humid night a couple of years back. Like many other desert reptiles, the monsoon and period after are the most active times of year. Humid air and cooler, stable temperatures make for safer activity, and a lot has to be done in a relatively short amount of time.
Southwestern Speckled Rattlesnake (Crotalus pyrrhus)
A Southwestern Speckled Rattlesnake hanging out in the shade on a blistering hot morning several years ago. This snake is still using this spot in the summer, staying cooler during the day and emerging at night, staying very near.
This is why, when we are called to capture a snake at a home during peak summer, we search for others. Especially without rain, they’re tethered to aestivation sites, never going far. If a rattlesnake is found on the back patio right now, there are only a few possibilities. It was either displaced by construction, tossed over the fence by the fire department, or it has been there for several weeks, successfully hiding as it always has before being discovered.
A Southwestern Speckled Rattlesnake from Yavapai County, Arizona, photographed earlier in the year. The combination of geology and lichen in the area produce some beautiful color combinations in the animals evolved to cryptically match it.
A Southwestern Speckled Rattlesnake resting along the top of a drainage after a night out. During the summer months, these and other rattlesnake species are primarily nocturnal, being encountered by people mostly in the hour before and after sunrise. As soon as the sun reaches the area, these snakes make a beeline for their aestivation sites to hide for the day.
The fact that rattlesnakes are often nocturnal and that they spend much of their lives avoiding excess heat is a surprise to many people. The misconception is that reptiles, ectotherms who get heat from the environment rather than produce it themselves, want it hot … the hotter the better. You’ll see this soon, in the form of comments like “it’s getting hot! It brings the rattlers out”, warnings from fire departments, and even articles in local news when temperatures stabilize in the triple digits for the year.
But thermoregulation means being the right temperature, not just as hot as possible. In fact, a body temperature sustained above around 105˚F can kill a rattlesnake. Interestingly, the upper terminal temperature seems to be similar across rattlesnake species, regardless of the environment they’re found. It’s often over 100˚F when these snakes begin their move back to their underground hiding spots, meaning they ride the line of death very closely, staying out as long as possible for the chance to find prey. If they are disturbed during this crawl for too long, or escape into the wrong hiding spot, it can quickly kill them.
We have learned this first-hand, unfortunately, from finding snakes within our study area who were first found by snake enthusiasts, likely mid-crawl. Thanks to Instagram, individual snakes that had died this way can be tied to individual events where a prolonged photo session and subsequent release of a heat-stressed snake resulted in death. To some herpers, it may seem like gatekeeping to discuss this kind of thing, but dead snakes are a lesson to those who would hear it.
During the summer, you may see us be critical of snake relocations performed by the fire department, and well-meaning individuals. This comes from the practice of releasing these snakes to improper cover, where they will be very unlikely to find survivable conditions in time. Every time you see a video of someone releasing a snake to open ground or random creosote mid-day, the relocator watches it crawl away and may be satisfied that they helped the animal … but these snakes do not survive for long.
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A Southwestern Speckled Rattlesnake rests in a rocky retreat, waiting for dark. Like other rattlesnake species in the Phoenix area, once temperatures stabilize in the triple digits, their activity becomes mostly nocturnal. The late afternoon is a good time to wait for a lizard or bird to make a mistake, in the meantime.
A Southwestern Speckled Rattlesnake making it difficult to tell where snake ends and rock begins.
A Southwestern Speckled Rattlesnake resting in the shade outside its summer aestivation den. It’s one of a handful that gather here each year to hide from the heat and gestate.
