Thursday, June 27, 2013

Guest Blog Post by Mike Hogan

The following is written by one of my field interns, Mike Hogan:

Ever since I can remember, snakes have captivated my interest and directed my academic focus in Biology and Herpetology. As a recent graduate of the University of Massachusetts Amherst, I jumped at the opportunity to work with the infamous North Pacific Rattlesnake as a summer field assistant. And after a month out in this beautiful reserve with great people and remarkable animals – life is good.

I find it amazing how much knowledge one can take away from studying a species. Just by looking at our research species, Crotalus o. oreganus, one could study behavior and discover evolutionary selective forces leading to such behaviors, or one could look at the venom and determine how regional distribution relates to toxicity and prey resistances, or one could sequence DNA from a number of specimens revealing gene flow, or record regional densities to establish the quality of various habitats… the list goes on. I think you can learn a lot by looking at one or two organisms and how they managed to combat selective pressures on our ever-changing planet.

Out of all the subfields of biology, behavior is definitely my favorite. I hope to someday incorporate snake behavior research into the venom industry, and observing free ranging predator prey interactions between ground squirrels and rattlesnakes is definitely an exciting step towards this goal.

Me, holding a tubed rattlesnake

But at the end of the day, the success of any research depends on the quality of the people involved with it. Each day I am surrounded by a group of hard working, compassionate field assistants with Bree as our fearless leader. A positive environment expedites the research, and I am glad to call myself part of such a great family here at BORR!

All the interns at the Oakland Zoo (on the day off of course)

Below is a quick video I put together using some footage I collected while in the field. Enjoy! 

Sunday, June 23, 2013

Meet the 2013 Interns!

From left to right: Mike (with one of our snake buckets and tongs), Jenny (with a boar's jaw), Lauren (with a gopher snake), Susan (with a kingsnake), and Joey (with a ring-necked snake)

Every year I take on several undergraduate field interns to help me with my research. This year I have 5 assistants from all over the United States. By working with me, they are hoping to gain valuable field experience that will prepare them for graduate school. In my opinion, they will learn more field techniques and research skills in their 8 weeks here than any college course can offer. 

Lauren shows
that snake bag 
can double as a
hat when needed

They work more than 12 hour days, 6 days a week. Every day, they perform several research tasks: radio-track the 20 tagged rattlesnakes, trap and mark squirrels, conduct behavioral observations and experiments on squirrels, collect measurements of squirrel temperament, help with presenting Robosquirrel to hunting rattlesnakes, just to name a few. They learn the difficulties that come with working in the field, the amount of effort it takes to collect behavioral data (for example only getting 1-2 samples per day), both of which lead to the surprising realization that research sounds so much simpler on paper than when being tested in person.  

I am very proud of them and I have asked each of them to write guest posts for my blog. Stay tuned for their thoughts on squirrel-snake interactions and how they find the field experience. I appreciate their hard work; after all, my research could not be done without them!

Joey transports a snake from a 
bucket to its glass terrarium 

Saturday, June 15, 2013

Good Friends and Snake Venom

My good friends, Matt Holding and Sloan Henningsen, paid a visit to our field site last week. Matt and I know each other from working in Dr. Emily Taylor’s lab at Cal Poly. Sloan is his awesome significant other and they make quite a terrific field team. Matt is now a Ph.D. student in the Gibbs Lab at The Ohio State University and we are collaborating on a project examining squirrel venom resistance and rattlesnake venom toxicity.

Many people do not know that ground squirrel blood contains proteins that neutralize rattlesnake venom. This means they can fight off the effects of envenomation, but are not immune (like how your body can fight off a cold). The level of resistance in squirrels correlates with blood volume – therefore pups are more susceptible to death by envenomation than adults. It was long thought that adults were essentially free from rattlesnake predation because of their resistance, but our research has shown that adults are commonly preyed upon by snakes.

Images of rattlesnake bite wounds from two different populations of ground squirrels. The top image shows the wound (circled in white) of a California ground squirrel with venom resistance. The bottom image show a wound caused by the same amount of venom in a squirrel without venom resistance.** 

For his dissertation, Matt is examining venom resistance in several populations of California ground squirrels.  My field site at BORR is one of the populations he is sampling from.  We are excited to see the composition of rattlesnake venom in relation to squirrel blood resistance especially since adult squirrels are eaten by snakes at our site. We are also interested in examining the individual variation in resistance (how resistance differs from squirrel to squirrel) and if this variation correlates with squirrel anti-snake behaviors (tail-flagging, alarm calling, substrate throwing, etc.).

Matt demonstrated several of his extraction methods while he visited us. Please enjoy the pictures below. Also, check out his awesome blog here.

 We scare a trapped squirrel into a bag

 Matt puts the squirrel under using a light anesthetic 

I measure various body parts on the squirrel

 Matt tubes a rattlesnake

We draw blood from the snake 

 Matt collects its venom (you can see some in the bottom of the glass)

**Image from: Owings, D. H., and R. G. Coss. 2007. Hunting California Ground Squirrels: Constraints and Opportunities for Northern Pacific Rattlesnakes. Biology of the Rattlesnakes.

Monday, June 10, 2013

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.