new snake – Page 2 – EYNC Rattlesnake Study

7 March 2015

There’s lots to report during the past 1.5 weeks…

On February 26, I came across another unidentified young adult rattlesnake at the refuge where so many others appear to have spent the winter. He or she was basking in the sun but escaped into the refuge, showing me in the process an unbroken rattle of about 7 segments with no paint. No time for photos, either. No other snakes were found basking that day.

I found Male 38 and Female 41 basking in the late afternoon on both 1 March and 3 March. Their body temperatures were 70F & 86F, respectively, on 3/1 and 84F & 90F on 3/3.

On the afternoon of 6 March, Female 41’s body temperature of 86F indicated she had been basking earlier but she was out of sight when I looked for her. By comparison, body temps for animals that have not basked recently have been around 10-14C (50-57F). While I did not find any of the marked snakes visible on 6 March, I did find a new male basking and captured him – CROR46. He has an unbroken rattle of 8 segments, making him relatively young but, at 264 g (9.3 oz), he is a good candidate for a transmitter. I will have to research the extended weather forecast for our area and if another cold snap looks unlikely, he will get a transmitter. I will also photograph his face and compare him to the unmarked snake photographed at this refuge on 14 February.

Just after 10 AM today (7 March) I found Female 41’s radio signal (her transmitter is not from the problem batch) rapidly increasing in pulse frequency, indicating she was cool but warming rapidly in the sun. Unlike some of the other basking rattlesnakes in the area, I have never found her basking in the open, out from under cover; she only exposes a small part of her surface area to direct sun while remaining sheltered. Take a look at the photo below and note how little of her was in the sun, yet her body temperature increased from 48F to 59F as I monitored it over just 20 minutes!

Finally, I spent some time around midday today checking some the favorite places for Males 36 and 37 – both are carrying dead transmitters. Surprisingly, I came across an adult rattlesnake at the base of the hill where both hung out last year. The snake was only partly exposed, with head and anterior body already in a hole and its tail hidden in the grass. Just as quickly as I saw it, it continued down the hole but not before I could clearly make out Male 37’s yellow/red rattle markings. Although I couldn’t capture him (without tearing up the environment, which I won’t do), he was 32 m (105 ft) from his winter refuge high on the hillside… so spring emergence is definitely underway! I have been told by several other people of recent rattlesnake sightings but this is the first of our study animals to be found away from his hibernaculum this year.

24 February 2015

Little has changed over the past ten days; fence lizards basking midday when it’s sunny but no rattlesnakes out when I have checked. The only interesting development was on 19 February, when I found that Female 41 had moved again, this time about 7 m (23 ft) to another smaller log where she was out of sight.

Today, I started collecting data on my Droid smartphone, rather than taking paper notes. Using a program called iFormBuilder, I have been able to create a menu that allows me to record twenty-nine observations of things like where a snake is, what it’s doing, temperatures, other environmental data, nearby flora, etc., mostly by making choices on drop-down menus. When I’m done, it automatically up-links to my computer at home where the data is waiting to be saved in an Excel spreadsheet. This not only helps standardize the data I collect but it saves an unbelievable amount of time by eliminating the need to manually enter data from paper notes. I used a similar system during my 40-month field study of Mohave rattlesnakes (2001-2004) and recorded something like 150,000 data points during more than 3700 encounters with the snakes; if that had been done on paper, I would still be working on data entry!

At 12:17 PM, I found a small unmarked male rattlesnake laying in the sun at the same refuge shared by CRORs 35, 38, 39, 40 and several others. He was captured (CROR45) and processed. At 242 grams (9 oz), he is large enough for a transmitter (the rule is the transmitter should not exceed 5% of the snake’s body mass, so my 9 g transmitters require a snake of 180 g (6 oz) or larger), however, releasing him with a fresh surgery when the weather is likely to be cold for weeks to come is not good. Physiological processes in ectotherms (animals that rely on the environment for body heat rather than making their own) slow way down when they get cool, which includes their immune systems and their ability to heal wounds. So Male #45 will be processed (measured, marked, etc.) and released where he was captured without a transmitter.

Before releasing him, however, I wanted to see if he was the same snake I saw on 14 February, since his body size and rattle looked very similar. But after comparing a photo of his face with my photo of the unidentified snake from 14 Feb, I found that they are not the same animal. In the photos below, note the difference in shape of the margin of the postnasal scale at (1), the speckling pattern of the preocular scale at (2), and the shape just under the eye of the margin of the dark postocular stripe at (3). Of course, there are many other dissimilarities in the photos… bottom line, it’s not the same animal.

The last development to report from 24 February is that I could not get a radio signal from Male #40. Thinking that he might have left the refuge with all the warm sunny days, I walked around for awhile without detecting his signal, so I returned to the refuge and used the burrow camera to look for him. Sure enough, there he was (yellow/blue paint in his rattle). This is the third transmitter to fail prematurely and all are from the same batch of refurbished units (they last a year and, after removal from the snake, are returned to the manufacturer to be rebuilt with new batteries). As I have mentioned previously, the manufacturer very rarely gets a bad lot of batteries which then affects an entire series of their transmitters. The good news is that I have no more of that batch of transmitters. The bad news: CRORs 35, 38, and 39 all have those transmitters in them. Transmitters have already failed in 36, 37, and now 40. Hopefully, I can catch Male #40 basking and catch him before he leaves the refuge – which could be any time, given the unseasonably warm days. I am reminded that one of those transmitters functioned for over a year in the last telemetered rattlesnake at my El Dorado Hills study site, so maybe all of them don’t contain bad batteries. Nonetheless, I will replace the transmitters in 35, 38, and 39 as soon as they leave their winter refuge, rather than waiting for their normal 12-month replacement.

14 February 2015

Since 2 February, fence lizards continue to bask on sunny days but the rattlesnakes have been out of sight and their low body temperatures suggest that they have not been basking.

However, another new unmarked rattlesnake was spotted today at 1:02PM, laying partly in the sun at the refuge used by most of the other telemetered animals. This one had a complete unbroken rattle of 7 segments plus the birth button and was a different rattlesnake than the one I saw on 2 February. It was in a place where I could not have captured him before he escaped so I didn’t disturb him/her. This is, indeed, a popular refuge. I can barely wait to see if all these rattlesnakes return next winter!

2 February 2015

Beginning with my first visit to the study site on 3 January, I began measuring ground temperatures with an infrared thermometer, rather than the mercury-filled glass thermometer I have used for a long time. The infrared thermometer is much faster (just point and pull the trigger) and actually gets the surface temperature, rather than the air just above the surface, since conduction with the ground has the biggest influence on the snakes’ body temperature unless they’re in direct sun.

3 January was also the coldest day I have experienced at this study site so far, with the shade surface temp at 4C (39F) at 10 AM. The body temps of males # 35, 38, and 40 (all in the same refuge together) were 45F, 50F, and 48F, respectively. Female #39, in the same refuge as the boys but several feet away, was 52F. Female #41, spending the winter by herself (as far as I know) in ground squirrel tunnels under a large live oak, was 41F.

On 2 February at 2:13 PM, I came across another small unmarked rattlesnake basking in diffuse sun (high thin overcast) at the refuge with CRORs 35, 38, 39, and 40. This snake fled into the refuge when I approached and was not captured.

Also on 2 Feb, female #41 had moved about 20 feet from among the live oak roots to under an old log she had used briefly last summer but she was out of sight either in or under it.

Interestingly, on every sunny day recently, fence lizards (Sceloporus occidentalis) have been active, basking on logs, despite the season.