The Field Season 2013 Begins!

Hi all!

I was finishing up my coursework the past months, but now I am back in business! The field season started three weeks ago and we are chugging along slowly but surely. I have five field interns working with me and they are wonderful additions to Team Crotalus (fyi - Crotalus is the genus for the rattlesnakes). This field season, our main focus is to conduct two field experiments testing the function of squirrel tail-flagging. We hypothesize that squirrels tail-flag to rattlesnakes to signal their vigilance and readiness to evade a snake strike. If this is true, (1) squirrels should evade snake strikes more often when tail-flagging and (2) snakes should strike less often at tail-flagging squirrels. We present a device to squirrels that simulates a snake strike to test prediction 1(see images below), and we use Robosquirrel to test prediction 2.  These experiments may sound simple, but working with wild animals can be unpredictable and frustrating (because they do not cooperate with you). It will likely take all summer to collect a large enough sample size to test our hypothesis.  

Screen shots from a trial with the strike simulating device. The focal squirrel is circled in red in the upper shot. At 0.00 seconds, the spring within the device (indicated by the yellow arrow) has not been released. By 0.58 seconds, the spring has been released and the squirrel has evaded it.

In addition to performing the abovementioned field experiments, we radiotrack 20 wild rattlesnakes each day. Since snakes are secretive and elusive creatures, we would not be able to understand how they interact with squirrels without knowing where they are at all times. We often catch glimpses of interesting behaviors because we track them so often. Please enjoy the video below that my intern, Mike, made showing the radio-tracking process and a great observation we made on our first day out in the field.   

Snake Yawns: adorable AND informative

Long time, no blog post! For this post, I wanted to share one of my favorite snake behaviors: yawning.

Snake yawning, also called mouth gaping, was once thought to only prepare snakes for engulfing large meals (by stretching their jaws and re-aligning the fangs). However, it is now recognized as a way for snakes to pick up chemical cues from their environment (Graves and Duvall, 1983, Barbour and Clark 2012). By opening their mouths wide, chemicals make contact with the vomeronasal organ (also called Jacobson's Organ), which resides above the roof of the snake's mouth. Tongue-flicking, a well-known snake behavior, also allows the vomeronasal organ to process chemical cues. The tongue catches chemicals in the environment and brushes against the roof of the snake's mouth to transfer these chemicals to the organ. Mouth gaping often occurs after snakes probe their heads forward and tongue-flick.  

Yawning also gives snakes charisma. When their "stone cold" countenance is interrupted by a yawn, you can't help but see their softer side. Even more importantly for researchers like me, yawns reveal hidden snakes in their environment. In my research, I use fixed security cameras to record the behaviors of free-ranging snakes. However, oftentimes I lose the snakes in my videos because they are well camouflaged with their surroundings. When they yawn, they open their mouths so wide that a white flash appears on the camera frame, thus revealing their location to me!

So in conclusion, I love snake yawns because they are adorable and informative.

References:
Graves, B.M. and D. Duvall. 1983. Occurrence and function of prairie rattlesnake mouth gaping in a non-feeding context. Ethology 227:471-474.


Barbour, M. and R.W. Clark. 2012. Diel cycles in chemosensory behaviors of free-ranging rattlesnakes lying in wait for prey. Ethology 118:480-488.

Sign the Petition to Cancel Rattlesnake Republic

As a rattlesnake researcher, I have found that these animals are much different than the media portrays them to be. For example, many people are unaware that they have docile temperaments, and exhibit maternal care and kin recognition behaviors. Rattlesnakes are also one of the most abundant predators by biomass in their environment, making them an integral part of the ecosystem. Their population declines could have cascading effects, which may drastically change food web dynamics. Thus, it saddens me that an "educational" channel like the Animal Planet would promote the slaughter of such beautiful and important creatures. If you have not already done so, please sign the petition to stop their show, Rattlesnake Republic, which glorifies hunters who kill rattlesnakes for profit. It serves no other purpose than to miseducate the public, propagate fear, and deter conservation efforts on those species currently in decline. Please sign the petition to cancel this show here.

Where the *bleep* are the snakes?!

My life has been crazy busy: finishing up the field season, travelling to Vancouver, and moving to San Diego from Davis. Now that I am finally settling down, I found the time to travel to BORR last weekend to check on the snakes and collect venom (we are collaborating with the Gibbs lab to examine individual and seasonal variation in venom composition). However, after two days of searching, we found ZERO snakes. Zip, nada, nothing! It's not like we were looking for snakes randomly. I have 20 of them with implanted radio-transmitters--this means I can track their exact location. However, after hours of tracking and re-tracking and re-tracking, NONE were on the surface. What the *bleep* are they doing?!

Northern Pacific Rattlesnakes mate bimodally. This means that they have two mating seasons: the spring and the fall. I was hoping to see mating activity last weekend, but instead I saw nothing. However, I did track several females to the exact same burrow as males. I found many male-female pairings and I found one two male-one female cluster. Although I could not see the snakes, I suspect they could be mating in shelter.

I also noticed that most of my snakes were hidden within rocky outcrops. This is strange for my site because there are very few of these. In the summer, snakes mainly hide in abundant squirrel burrows, but I did find that they tended to overwinter in the outcrops. This makes me wonder if they are moving to their overwintering sites early. Normally overwintering ("hibernation") begins in November and lasts through March. Check out the nice outcrops the snakes were in:

One snake in here:

One male and one female shacked up here:

TWO males, one female here:

The weekend wasn't a total loss though. We saw a nice little spider crossing the road and found that one of our females gave birth:

Tarantula!

A little baby outside its den:

Who knows what the snakes were up to? Maybe it was just too hot of a weekend. So much for me collecting venom...