Squirrels May Smell Out Snakes - guest post by Jenny Schefski

Jenny is one of my interns this summer, but she has been working with me since fall semester last year. She started reviewing video data from the 2012 field season, and now she is conducting her own independent project. She has graciously written a guest blog post describing her exciting research. See below:

This summer, I am studying the ability of California ground squirrels (Otospermophilus beecheyi) to detect and discriminate between two snake predators using olfactory cues. Thanks to the previous research of behavioral ecologists, it has been well established that California ground squirrels can visually recognize snakes along with snake-like patterns and objects.  Additionally, California ground squirrels have been shown to display distinct sets of behaviors towards the venomous northern Pacific rattlesnake (Crotalus oreganus) and the nonvenomous Pacific gopher snake (Pituophis catenifer).  However, little is known about their olfactory capabilities and what role olfaction might play in their detection and avoidance of snake predators.  Because gopher snakes and rattlesnakes are cryptic and often dwell in dark burrows, ground squirrels cannot always rely upon vision to detect them.  Therefore, it would likely benefit ground squirrels to have some sort of olfactory perception of snakes.   

I have strategically placed a rattlesnake model next to a squirrel burrow (top) 

and use snake tongs to handle a gopher snake model (bottom). 

Do you think they will fool the squirrels? 

To gain more insight into this fascinating predator-prey dynamic, I am filming ground squirrel interactions with visual and olfactory snake cues.  I create such cues by using rattlesnake and gopher snake models that are left unscented or scented with their respective odors. I place these snake models next to squirrel burrows and hope that squirrels interact with them.  I use security cameras to record squirrel interactions so that I can later quantify behaviors to see if visual detection of snakes is aided by olfactory and/or visual cues.  Additionally, I am scenting dirt with snake odors to see if grounds squirrels can detect snakes using olfaction alone.  Finally, I look forward to later quantifying the squirrels’ interactions with my treatments to see if they display different behaviors towards gopher snake cues versus rattlesnake cues.  

I position one of my security cameras over a squirrel burrow. I will leave it running 

all day to opportunistically record squirrels interacting with the rattlesnake model

I measure the distance of the model from the burrow

The snake model is set up (bottom right corner) and the security camera 

is set up to record squirrel encounters

The video footage I have reviewed so far is intriguing and looks promising.  I am excited to squeeze in as many trials as I can in my last two weeks here at BORR, and I look forward to reviewing all of my footage thereafter! 

Rattlesnake Researchers Knee-deep in Ponds?

Rattlesnakes are awesomely beautiful creatures that I greatly enjoy working with. However, every once in a while it’s nice to marvel at other animals for a change. Fortunately, we have many opportunities to learn about different animals in the area from the other researchers that utilize the Blue Oak Ranch Reserve. One such researcher is Rachel Anderson, a Ph.D. student in the Lawler Lab at UC Davis. I have known Rachel for over a year now; we first met on the UC Davis Odyssey (a GREAT grad student orientation trip that occurs every year). She just started her research examining the relationship between invasive bullfrogs and native California red-legged frogs. She came to BORR a couple of days ago and graciously let us tag along while she collected samples from a few of the ponds.  

 Rachel demonstrates how she catches bullfrogs

What a change it was for us! Rachel collects all of her data at night when it is easiest to catch frogs. In contrast, we work during the day, roughly from 7 am to 5 pm. I’m not going to lie; working at night is hard when you are accustomed to going to bed at 9 pm.  However, working in the cool night air was much better than the blazing hot sun. The most extreme change for us was actually getting wet! Many of us (including myself) had never waded in murky, muddy ponds so it was definitely a new experience. Rachel let us borrow waders, overall-like pants that prevent water from getting your clothes wet (that is, if you don’t go too deep). We dove right in (not literally) to help her spot frogs. One pond was so full of bullfrogs you almost could not avoid stepping on them. Rachel caught a few red-legged frogs and showed us their beautiful coloration. To my surprise, these frogs make one of the cutest sounds when they are captured, as if they are pleading with you to let them go. We also found a beautiful garter snake, and our most unexpected surprise was a rattlesnake! Joey, one of my interns, spotted a rattlesnake right next to the water. They are known to swim, but was this snake attempting to ambush frogs? It was indeed a strange encounter. 

Kissing prince charming

Lauren got a two-for-one

Pretty little garter snake

We did not return back to the field station until around midnight – awfully past our bedtime! We immediately passed out in our tents, exhausted from so much froggy excitement, and arose the next morning bright and early ready for another day of snakes and squirrels.