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Monday, December 19, 2011


Are snakes social? YES! Do snakes live in groups? SOMETIMES! Are these groups of snakes extended families? Help us find out!

As a reader of this blog, you already know that rattlesnakes are quite gregarious. Their social lives are complex; they recognize and preferentially associate with their siblings, care for their kids, and even help care for their neighbor’s kids. But the big question remains unanswered.

Many of us who monitor rattlesnake dens have speculated that they are composed of closely related individuals. Our goal is to explore this idea by examining relatedness with microsatellite DNA markers. With your help, we will find out if dens really are a rattlesnake family reunion. Our research might reveal a previously undocumented, complex social system in snakes and promote snake conservation by highlighting some very human-like behaviors.

You know you're curious about the relatedness of the snakes you've been reading about here! Check out our project on RocketHub.

And spread the word! This can be just as helpful as a financial contribution.

Sigma vs. the squirrel

Friday, December 16, 2011


Squirrels and rattlesnakes have a complicated relationship. Some squirrels have developed resistance to rattlesnake venom so that an adult squirrel can survive a rattlesnake bite. Juvenile squirrels cannot, so they are often still prey to rattlesnakes. Because of their resistance, adult squirrels will confront rattlesnakes that wander near their colonies and sometimes even kill them!

For more information on rattlesnake-squirrel interactions, check out research from Rulon Clark’s lab and his student Bree Putman’s blog. Now on to Sigma’s story…

We first met Sigma on 23 April 2011 when she was basking near her den. She was named for one of her many weird blotches that is shaped like the Greek letter. DSC_0337 Sigma and Barb, 24 April 2011. Barb was born here, to another female (Devil Tail), the previous September (2010).

6 August: We return to the dens and find Sigma at large rock near her den that will be her nest site. Toward the end of her pregnancy, she settles on the west side of the rock as her main basking area, so we set up a timelapse camera there.

Between 3 and 4 September, the squirrel appears to be investigating the nest rock, but never when Sigma is on the surface.

On 5 September, Sigma and the squirrel meet: WSPC2058 Sigma (at end of arrow) emerging for the first time that day

WSPC2059 The squirrel confronts Sigma

WSPC2060 Sigma immediately retreats beneath her nest rock

6 September: Sigma sticks her head out and looks around before emerging (like Cap Mama ). About an hour later, the first of her four neonates emerge from beneath the rock: WSPC2697

The following video captures Sigma’s family’s first day together (warning: its kinda long, 4 minutes). Watch for the squirrel’s appearance at 12:14PM.

The squirrel does not return (that we can see) the following day and the family spends most of it on the surface: WSPC4661


Timelapse video of 8 September:

What starts as a peaceful day for the family was rudely interrupted by the squirrel at 11:27AM. Just before the squirrel appears in the video, Sigma turns and assumes an S-coil defensive posture typical of rattlesnakes: WSPC0295 Sigma at rest with her family

WSPC0296 Sigma turns, expands her body to look as large as possible, and assumes a ready-to-strike (S-coil) defensive posture.

What you can’t see in the video was captured by our overhead camera; Sigma is posturing to the squirrel just off screen: MDGC1954

The family immediately disappears; Sigma reemerges only after the squirrel is gone. The first neonate to emerge is quickly chased back under the nest rock by the squirrel (~11:54AM–12:01PM in the video).

9 September: After the squirrel interactions, the family seems to spend much less time on the surface (at least where the cameras can see). We recorded only one additional, indirect, interaction between Sigma and the squirrel:
As it often did when there weren’t snakes visible, the squirrel appears to be looking underneath the nest rock. Sigma returns, takes on the familiar defensive posture and appears to be rattling – although it’s difficult to be certain because the timelapse photos were taken at one-minute intervals.

Our camera continued to record at this location until 18 September and the squirrel returned about every other day, usually looking underneath the nest rock. Sigma and her four neonates were never seen together again, but we cannot say if they changed their behavior or if one or more neonates were injured or killed. One limitation of remote photography is that our knowledge is limited to what happened in view of the camera. However, it is unlikely that any of these squirrel-rattlesnake interactions would have occurred if a human observer was present. We never saw anything like this when we monitored rattlesnake families in person – have you?

Basiliscus Family Values

Friday, December 9, 2011


You didn't think that Arizona black rattlesnakes were the only ones to take care of their kids, did you?

Crotalus-basiliscus-08271 by Young Cage

In a recent post on the Field Herp Forum, my friend Young Cage describes a series of observations of a family of Mexican West Coast Rattlesnakes (Crotalus basiliscus) . Young is an excellent photographer, so the post is worth checking out just to look at the pictures.