Um, is this a rattlesnake?

Oh dear, never a dull moment up here in the East Mountains. I discovered this snake waiting for me at my back door this morning.

I didn't see it when I stepped out the door – it’s actually lying on the threshold of the full-length window NEXT to the door, thank goodness - but one of my dogs went into a whimpering, curtseying dance at the threshold and refused to go out.

Then I heard the rattle ... a sound I'd never heard before, but made my hair stand on end.

The dogs and I ran away; I came back with the camera.

I assume from the sound that this is a rattlesnake? It was about 2 feet long, but only an inch or so in diameter. I’m guessing from the size that if it’s a rattlesnake, it must be a young one.

The weird thing is, the head isn't as strongly wedge-shaped as other pit vipers I've seen (in Belize, not here). You can see its head better in this closer photo, taken from the safety of indoors:

Soooo … is there another kind of snake in New Mexico that makes a warning rattle? Did I actually hear a rattle, or was it just a hiss? It sounded like a rattle, according to my ancient rat brain.

If it is a juvenile rattlesnake, I’ve just read that they’re considered the most dangerous:

Rattlesnakes are born with fully functioning fangs capable of injecting venom and can regulate the amount of venom they inject when biting. Generally they deliver a full dose of venom to their prey, but may deliver less venom or none at all when biting defensively. A frightened or injured snake may not exercise such control. Young snakes are to be considered more dangerous, as they have less control over the amount of venom they inject. [1] A young rattlesnake will often simply inject all its venom, which might be a lethal dose, depending on the bitten animal.

(1) "Venomous Snakes". National Institute for Occupational Health and Safety Topics. Centers for Disease Control.

Aaargh.

--MaggieBelize
Designer, kNotes for kNitters
Sandia Park, NM

UPDATE: Thanks to the friendly local folks on the Albuquerque City Data Forum, I now believe that this is NOT a rattlesnake, but a bullsnake, which resembles it.

Bullsnakes are NOT venomous, and I’m told should not be killed as they are of no danger to humans and eat large numbers of rodents.

Bullsnakes may vibrate tail when alarm, which may sound like a rattlesnake, also makes a hissing noise. However, they may from time to time get hit over the head with a hoe for doing too effective a job of acting like a rattlesnake.

I feel better already, especially since I didn’t kill it.