Tuesday, October 25, 2011

Vandenberg Rattlesnakes

PERL has now begun conducting research on rattlesnakes at Vandenberg Air Force Base! This gorgeous area occupies a gigantic swath of land in northern Santa Barbara County. Most of it is pristine, inhabited not by humans but by a motley crew of flora and fauna, including lots of threatened and endangered species. And it is FULL of rattlesnakes-- most definitely neither threatened nor endangered.

Near the beach there are beautiful dunes:

And inland there are rocky hillsides (that's the city of Santa Maria in the background):

We saw about 15 rattlesnakes just in the rocks visible in this photo:

These are Southern Pacific rattlesnakes (Crotalus oreganus helleri), whereas for the past six years we have been studying Northern Pacifics (C. o. oreganus) about 50 miles to the northeast. It's probably a big intergrade zone, really.

Since it's fall, and the air is cool but the sun is warm, most of the snakes are hiding under the rocks, sticking body parts out into the sun:

In the words of Roger Repp, "Where's Waldo?" (Hint: There are two rattlesnakes in this photo.)

Rodent burrows are also favorite spots for snakes to hang out:

In two days out hunting, we saw about 10 male-female pairs! The Northern Pacifics would have been done with mating season by now (because inland it's cold at night?), but the coastal snakes are apparently going strong. If you look closely you'll see a little girl under this boy:

The big question is: Why are there so many snakes here? Could be the weather, could be the isolation from humans, definitely is the massive number and variety of rodents. Everywhere you look you see mouse burrows:

Ground squirrel burrows:

And gopher mounds:

The result is heaps of rattlesnakes that grow FAST. See this medium-sized male that Scott is holding?

Look at his rattle! This snake is no older than three years. He's huge for that age! Nothing like a steady supply of tasty voles to fuel rattlesnake biomass.

And one more cool thing: BABIES! (These are Northern Pacifics from inland though)

Stay tuned for a lot more snakey updates from VAFB!