Spring emergence has begun!

It took only a few days of moderately warmer weather to stir our sleeping rattlesnakes. I haven’t downloaded my temperature logger recently but it has been easy to notice that it’s in the 50s instead of the 30s the past few mornings, while daytime highs have been in the high 60s.

And today, we found some rattlesnakes stirring. Until now, the body temps of all of the hibernating rattlesnakes have been in the single digits Celsius (less than 50F). Earlier today, ten of twelve telemetered rattlesnakes were in double digits despite a full thick overcast. Male 37 – still inaccessible on the bluff – produced a calculated body temperature of 21C (70F). (The bluff is always warmer because it is steep and faces south, so solar energy is more concentrated per unit of surface area.) Male 37 is clearly no longer deep underground.

Next was Male 46 at 16C (61F) and, sure enough, he was peering out from under the log where he spent the winter.

Male 46 around midday today, 10 March 2017, peering out from under his log.

When we arrived at Female 41’s radio signal, we found a rattlesnake laying out in the grass and assumed it was her. The rattle was not clearly visible at the time but later examination of photographs disclosed white/green paint in the rattle. Female 41 is white/blue and the rattlesnake we observed turned out to be Male 49, marked and released without a transmitter exactly two years ago today, on 10 March 2015! Female 41 was very close but out of sight.

Close examination of photographs proved this snake to be Male 49 (white/green), not Female 41.
Male 49, as we first observed him; 10 March 2017.

We also found Male 40 laying out in the same spot as last week (see the blog post on 6 March), plus we found a new animal laying in the grass next to another large log where two telemetered adults have been napping since last fall. He (or she) was captured and, while too small for a transmitter, will be measured, marked, and will donate a blood sample before being released as CROR81.

More news to follow!

9 December 2014

12:58 PM; 100% thick low overcast, 15C (59F), everything is wet in between two significant rain events.

I heard the sound of a wet rattle rattling at the log where four of our telemetered snakes are located and found a small unmarked male in the new green grass – CROR44 (I’ll explain “CROR” below).  This snake is small at 638 mm (25 inches) and 141 g (5 ounces) but has a broken rattle with only two segments.Coo44 rattle 100dpi_4x6 Upon closer examination, this little guy was found to have some fresh and significant trauma to his posterior abdomen and tail area, including a deep penetrating wound at his cloaca (derived from the Latin word for sewer, the cloaca is the single vent that empties the digestive, urinary, and reproductive tracts in lower vertebrates). Since this rattlesnake was about the same size as the unmarked snake I saw but didn’t capture at this log on 15 November (see photo of tail in 2014 Update #13), I compared scale markings on the tail with the photograph and concluded that this is the same rattlesnake. Sometime in the past three weeks, something got a hold of this snake before he could get all the way under the log and injured him severely, as well as pulling off most of his rattle (the rattles are hollow, brittle and easily damaged). Since my study intends to observe and document natural occurrences (and my permits do not authorize interference in the natural processes), I measured and marked this injured snake (no transmitter surgery) and released him under the log. I am doubtful, however, that he will survive, as his abdominal wound looks deep and they do not heal well when they are cold (e.g., over the winter).

After checking on all of the other telemetered rattlesnakes (none had moved recently), I checked on male #37 on the hillside and found only static at his radio frequency. Given the time of year, the cool weather, and the fact that all other snakes seem to be down for the winter, it is hard to imagine that anything has happened to him. His transmitter has simply failed prematurely, just as the radio in male #36 did a few weeks ago. This is not a common occurance but tends to affect multiple transmitters when it does occur because they were often refurbished from the same batch of batteries. Like male #36, we can only hope to find him in the spring, either around the buildings or courting a telemetered female. I think there’s a good chance of that, though.

An explanation of CROR: Taxonomists and other biologists, at least in the herpetology field, seem to be moving away from the subspecies concept. In giving study animals identifying monikers, we have long used the initials of the genus, species, and subspecies names, plus a number. Thus “Coo36” would be Crotalus (the genus) oreganus (the species) oreganus (the subspecies) number 36 (if he were a southern Pacific rattlesnake, he would be Coh36 for Crotalus oreganus helleri). As taxonomists continue to either lump subspecies together or elevate them to full species status, the numbering convention had to change. So now we are using the first two letters of the genus and the first two letters of the species, so Crotalus oreganus #36 becomes CROR36!