Tuesday, June 28, 2011

What Goes In Must Come Out (but maybe not like this)

As the summer progresses, the snakes are eating more and more. I have witnessed four small mammals being swallowed by rattlesnakes: two squirrel pups and two mice. Furthermore, we have seen several snakes with food bulges (aka full bellies). In order to determine the diet of our population of snakes, we have made a few snakes regurgitate their meals. We found a pup in a small juvenile snake and an adult squirrel in an adult snake. Both of these meals are very interesting because they are large for these two snakes to eat (half of their body weight!). Also, adult squirrels are resistant to rattlesnake venom so it is interesting that an adult squirrel was ingested. Maybe our population of squirrels is not as resistant as we think. Check out natural snake feeding events and our regurgitation methods below!

Chewbacca eating a pup

Making a juvenile reguritate

 The finished product

 Posing with a partially digested squirrel

 An adult snake regurgitating an adult squirrel

Thursday, June 23, 2011

Robosquirrel is Struck!


We have been presenting Robosquirrel to snakes in ambush position. During one trial, a snake actually struck the head of the robot! It also left a pool of venom on the head which we collected into a syringe. This is interesting because one hypothesis as to why squirrels tail flag in front of snakes is to deter them from striking.  During this trial, the robot was not tail-flagging presumably allowing the snake to strike more easily than if the robot had been tail-flagging. We need to perform more trials to see if any patterns emerge. Enjoy the video!

Monday, June 13, 2011

ROBOSQUIRREL lives!

I am lucky that I am able to use biorobotics in my research. This means that I can actually test the hypotheses we have about squirrel tail-flagging. Currently, all we know about tail-flagging is based off of observations of live squirrels interacting with snakes, but in order to test the true function of this behavior, we need to manipulate the tail-flagging signal. We obviously can't do this with live squirrels (for logistical and ethical issues), but thanks to a collaboration with engineers at UC Davis, we can use Robosquirrel instead. We are using Robosquirrel to test how snakes perceive and respond to the displays made by ground squirrels.

In the wild, once squirrels detect a snake they will approach it and tail flag (move their tails back and forth). Additionally, squirrels heat up their tails (increase the thermal signature) in response to rattlesnakes (which sense infrared heat using pits on the sides on their heads), but they do not do this in response to gopher snakes (which cannot sense infrared heat). We want to know if heat truly is important in this display. Does it decrease the snake's ability to pin-point a strike? Does it make the squirrel look bigger? Does it help the snake "see" tail-flagging better, especially if it is dark out?

Also, what does the tail-flagging do for the squirrel? Does it communicate something to the snake? Does it prevent the snake from striking? Does it make the snake abandon the area? By presenting Robosquirrel to snakes with and without tail-flagging, and with and without infrared heat, we hope to answer some of these questions.  

Robosquirrel at the end of its track. We glued grass to the track to conceal the metal box that hides the electrical wires under the robot.  

The robosquirrel experimental setup. We lay down the track to within 30cm of a snake burrow. We set up a blind and wireless security camera to watch the snakes stealthily. Once the snake emerges and assumes ambush position we are ready to roll robosquirrel into position and give a display.   


 Robosquirrel ready for action!

The synchronized tail flag dance
video

Wireless Video Cameras Finally Working

The reason we picked BORR as our field site was because they have a tower system that spreads wireless internet over most of the property. Our goal is to monitor snake activity in real-time (via the internet) so that we can record squirrel interactions when they actually occur as opposed to reviewing hours of recordings at a later date. Unfortunately, the wireless did not reach the part of the reserve where we found all of our snakes. Luckily, we were able to set up another tower that transmits the wireless signal to our site. This week we finally started to use our wireless security cameras in the field. Check out this awesome use of technology below.

Camera set up in the field. All the camera equipment is stored in a backpack in a large black trash bag next to the tripod (to protect it all from the elements).  

Close-up of our "hi-tech" snake cams. The head of the camera can pan, tilt, and zoom as needed.

Friday, June 3, 2011

My First Snake Surgery!

Like I wrote before, our external transmitter attachment turned out to be an unsuccessful attempt. Thus, we had to surgically implant the transmitters into the body cavity of our snakes. This is a common practice among snake researchers, and snakes usually recover with no problems within a day. Rulon walked me through the steps of my first snake surgery so that I can independently insert transmitters into future snakes.  

Palpatin knocked out and ready to go


 Making the first cut with the scalpel. I cut the skin between the first and second row of scales, an incision about 5 scales long.  

Rulon instructing me in the process

Opening up the body cavity

Inserting the transmitter

Rulon shows me how to give the snake mouth-to-mouth if necessary. You insert a tube into its glotis and blow--same as CPR but without the chest compressions

Nice close-up of the head