Love in the Rocks

Behavior, Social behavior / By

On a balmy August night, Melissa and I headed up a canyon near our home. We had explored this area during the day, but recent night visits revealed orb-weaver spiders, rattlesnakes and vinegaroons hunting under cover of night. Though the pine forest air cools off quickly after sunset, rocky canyonsides hold heat a bit longer, which the ectotherms appear to appreciate. And we appreciate the easy access to this beautiful and (sometimes) bustling area near our home.

A pair of Western Black-tailed Rattlesnakes huddle in vegetation at night.
These two Western Black-tailed Rattlesnakes wonder who is intruding on date night.

On this particular Wednesday, we wandered up-canyon, but were not finding much of interest. On a whim, we made our way up and over a low divide and down into a small tributary with similar rocky flanks. Just when we were feeling that it was time to head back, my flashlight beam caught a familiar sight – the golden glint of a Western Black-tailed Rattlesnake, our most commonly encountered rattlesnake in these woods, coiled beside a boulder and overtopped by the prodigious monsoon vegetation. We peered from afar, and although we could easily make out one coiled body, we could see two heads looking back toward us.

As we approached for a closer look, the second head reeled back to his own coils beside Sugar, as we would come to call her (so named for her sweet disposition, even though most Blacktails are mild-mannered).

A close-up of the female Western Black-tailed Rattlesnake. She is coiled and hefty, with brown blotches on a lighter yellowish background.
A closer look at Sugar, the female.
A close-up of the male Western Black-tailed Rattlesnake. He is coiled but looks a little apprehensive, with his tongue out. He is more yellow than the female.
Leander, a young male, was a little more nervous than his ladyfriend.

Her consort, Leander, was smaller than her and rather skinny; it appeared that his interest in Sugar outweighed his appetite for other woodland critters, at least in this moment. In most rattlesnake species (Blacktails included), males grow larger than females. When a female attracts multiple suitors, size matters. Large males typically win her favor over scrawnier opponents (settled through ritualized combat), but the drive to reproduce often creates alternative strategies for success. For example, female Western Diamond-backeds may bear the offspring of multiple fathers in one litter. As a little guy, being the first to find a potential mate may be his best tactic, at least until he’s big enough to drive away rivals. In any case, without a challenger, we expected Leander would court his big ladyfriend as long it took to convince her of his devotion.

We snapped some photos of the two to record distinguishing features that might help us recognize them in future encounters and headed home. It’s best to end any outing on a high note, and minimizing our disturbance to these snakes will improve our chances of seeing them again.

Courtship may last for many days in rattlesnakes, so the next morning we decided to check in on the two lovebuns. We found they had moved a short distance downhill, entwined prominently in the opening of a recess beneath a rock. In the light of day, we first used binoculars to spy on them.  Leander rubbed his chin along Sugar’s back and his tail wrapped around hers; both actions communicated his intentions and induced her receptivity. Melissa was first to observe that they were copulating, noting that Sugar’s back end was slightly distended from their conjugation.

In the summer sun their bodies soon became too warm, and Sugar drew to the shade with Leander in tow. Snake hemipenes are hammer-headed (pardon the crude simplification – the morphology of the male’s paired appendage is intricate and complex), so once inside and engorged, the ability to disconnect without injury means patiently waiting out the transfer of sperm and relaxation of the hemipenis. Until that happens, he must go where she decides, though often in reverse. To keep from damaging his sensitive parts any more than necessary, Leander did his best to keep that critical connection to Sugar slack as she moved into shade.

As we often do, we left video cameras recording while we wandered out of sight to reduce the amount of time we are hovering and potentially disturbing the activity of our favorite subjects. We ended up with five hours of intimate footage to review, which I whittled down here:

We were amused to see this surprise cameo:

A medium-sized Gophersnake crashed the affair, but clearly had little interest in the lovers and kept moving. Sugar, at least, was unnerved by the interloper, and decided it was prudent to clear out.

Shortly after the interruption by the Gophersnake, Melissa came by to collect the video camera. She found Sugar leading Leander out of the shelter (ouch!) and assumed that her own presence had disturbed them. She recorded the moment on video and headed home.

The female Western Black-tailed Rattlesnake is by herself, coiled in the shade against a rock.
After parting ways, Sugar rests in shade.

We checked on the pair again Friday morning. It was surprisingly easy to spot Sugar, alone and relaxing at the edge of deep shade not far from where Melissa left the pair the previous afternoon. As unreactive as ever, she afforded us some photos that we used to confirm it was actually her.

After a few moments, Melissa perceived Leander crawling through some vegetation just a few meters away, heading downstream.

We watched him crawl to a nearby Packrat nest, flicking his tongue with interest, and coiling in the shade of a Canyon Grape vine. Having apparently successfully mated, his attention now turned to another biological imperative: food! We wished him luck and departed.

The female Western Black-tailed Rattlesnake is beneath a rock.
Two days later I find Sugar relaxing 50 m downstream. The lack of an “S” shaped neck indicates a resting posture, rather than one used for hunting.

On Sunday morning I thought I’d see if I could find either snake and took a stroll up what we now call Courtship Canyon. Fifty meters shy of their area, I felt an urge to begin searching. I left the canyon bottom for a boulder big enough to provide a Blacktail with shelter. I was stunned to find Sugar right in front of my eyes, relaxing in a coil beneath the boulder!

She seemed to have an unusual ability to draw in admirers! Usually a snake need not move far before hope of finding them is lost. But not this time; as if by some unseen force, she drew me in to her exact resting spot.

The ease of this last encounter inflated my perception of my ability to find one specific wild snake. So the next morning, I dragged Melissa to this satellite boulder only to find that Sugar was not underneath. But just before declaring she had moved on, I elevated my gaze ever so slightly:

  • Next day, my tunnel vision searched for Sugar beneath the rock. She was not there!
Wide shot of the boulders upon which the female rests.
Thank you Sugar!

I thank Sugar and Leander for tolerating our visits, as they surely would have preferred privacy. We try to use the least invasive methods to study these animals, and back away at visible signs of irritation or duress. It is our hope that the stories and videos we obtain will help deepen folk’s awareness that snakes are just like any other animal: they may share tender moments with one another and would prefer to be left alone.