March weather had the rattlesnakes along the American River Parkway confused! As I have mentioned before, the rattlesnakes usually emerge and begin to bask when the average temperature at ground level remains at or above about 50F. They are usually deep enough underground during the winter to escape daily high and low fluctuations, so it is the average that eventually penetrates to them and signals that winter is likely over. But not this year.
Most telemetered rattlesnakes emerged in March but remained at their hibernation sites, basking on sunny days as they usually do before leaving their winter shelters. But rather than getting drier and warmer, the weather throughout April was a constant mixture of rain and cloudy cool days and nights. Of the few rattlesnakes that left their winter hibernacula, two returned while others became inactive at other sites. The rattlesnakes do just fine in the rain. In fact, they drink rain and dew when it’s available. And cloudy weather is not a deterrent to activity if it is accompanied by warm temperatures. But nighttime air temperatures below 50F followed by overcast cool days are not good for activity in animals like reptiles that depend on the environment for their body heat.
So, in late March and throughout April, the few stretches of several sunny days with relatively warm nights in between produced some sporadic rattlesnake activity. But it was not until the end of April that more consistent sun and heat produced vigorous widespread rattlesnake activity.
As expected, when we had activity, we observed lots of courtship. This is, after all, the peak of courtship activity, followed by almost no reproductive activity from June to mid-August before an untick in courtship again in the fall.
But by far the most interesting discovery this spring was by one of my UC California Naturalist students who found a small male rattlesnake with no rattle! (See photos below) Now I hesitate to mention this, for fear of starting a panic about rattleless rattlesnakes. Please remember several things:
- Rattlesnakes missing their entire rattle are extraordinarily rare. So rare, in fact, that they usually rate a note in a biological journal. This one will!
- No rattlesnake has a long pointed tail like our many harmless snakes.
- Rattles can be missing due to either injury or genetic mutation.
- This little snake appeared to be recently missing the end of his tail and had other serious but healing injuries. Apparently a close call with a predator!
- Identify rattlesnakes by looking at the tail! Yes, rattlesnakes have elliptical pupils and heat-sensitive facial pits but some harmless snakes have elliptical pupils and both these characters are too small to be clearly seen from a safe distance (two-times the length of the snake). Some harmless snakes also have rather triangular heads, especially when they have been frightened and are behaving defensively. But no rattlesnake has a long pointed tail like our harmless snakes and all of California’s dangerous snakes are rattlesnakes.
Check out the following images…
To be sure, there are dangerous snakes in other parts of the United States that have long tails without rattles (cottonmouths, copperheads and coral snakes, in southern and eastern states). But in California and other northwestern states, the only dangerous snakes are rattlesnakes.
Look at the tail to identify rattlesnakes!
And, yes, Male 87 was processed and released, just like all the others. While he has no paint in his rattle, he won’t be hard to recognize!