Sidewinders are one of my favorite things to search for, and have spent a lot of time with them during the day. I have been fortunate enough to track and locate all three subspecies in various localities. Here are a couple tips and photos that may be able to point you in the right direction. I applaud you for pushing past the standard road-cruising, and attempting to get your actual boots on the ground! Finding rattlesnakes in general coiled in-situ, observing natural behavior and getting photos of them in that way can be extremely rewarding. If you have the good sense to have a hands-off approach, take copious
amounts of notes, try not to over-exploit the animals, and keep a minimal amount of human visitation to the areas you have found, you will find that you will observe more and more of that natural behavior and get the thrill of maybe even watching the exact same animals for years to come. That seems to be the formula that a lot of these long-time herpers use to see mothers with clutches of babies, predation, mating rituals, and so forth. I don't claim to be perfect in this formula, but I strive to be better and better every time I set foot in the field.
Anyways... we are talking about winders here! Here are some photos before I get into it.
C. c. laterorepens
C. c. cerastes
C. c. cercobombus
The Sidewinder account on the Reptiles of Arizona Website has some great resources on location in the Behavior
section http://reptilesofaz.org/Snakes-Subpages ... astes.html
BEHAVIOR: Nocturnal and crepuscular during the hot summer months, it shelters in underground burrows during the day. It is diurnal and crepuscular during spring when it is often encountered coiled on the surface in the partial shade of a creosote bush. In sandy areas this snake often coils partially buried in the sand, sometimes with only the head and dorsum exposed. This ground-dweller's distinctive method of locomotion (side-winding) involves the snake moving sideways with its body winding through an "S" shaped curve. While side-winding only a few points of the snakes body contact the hot sand at any one time. This method of locomotion leaves distinctive parallel J-shaped tracks with the hooks of the "J"s pointing in the direction of travel. Like the other "pit-vipers" (members of the subfamily Crotalinae) this snake uses heat sensing pits (one on each side of the face between the eye and nostril) to detect warm-blooded predators and prey.
In terms of dialing in timing and microhabitat, I'll let the above resource be the compass and personal experience be your best teacher. Basically put though, use common sense - when the temperatures are the most suitable for reptile activity, you will see winders. They are not extremely picky it seems. If you have any experience searching for crotes, apply that for this given situation. As far as tracking goes, here are a couple photos and tips for following these guys.
This method of locomotion leaves distinctive parallel J-shaped tracks with the hooks of the "J"s pointing in the direction of travel.
Here are some photos I have taken of these tracks in MX, UT, and AZ. You can see the distinct "J"s in the tracks, and as the guide explains the "hooks" of the tracks point in the direction of the animal's travel. The hooks are made by the neck and head of the animal as it travels, which is contrary to what it may seem. When I first started I thought they were made by the tail.
For these two photos, the tracks are headed towards me.
The last one shown here is headed away from me.
That should give you a good feeling of what to look for and how to follow. I will say - remember to pick your battles! Look for the freshest tracks you can find, which are usually the ones where you can clearly see the belly scutes. Sidewinders are notorious for covering a lot of ground if they want to. There have been times that I have following tracks for what it seemed like 50-100 meters. If you choose a faded and old track, your time may just be better spent covering ground in suitable habitat searching for incidental snake finds or fresh tracks. Another tip for tracking would be if you are doing it at night or in the dark, hold your light low to the ground and watch the tracks illuminate!
Some other things to look for are "craters" left by winders who sat in an area and then left. The fresh ones will look like inverted cinnamon rolls with belly scutes. The belly scutes are key - you'd be surprised how often you can be deceived by a track made by a kangaroo rat who sat for a while to eat or rest and it's tail makes some interesting track. Seems wonky and hard to believe that it could get you, but it does.
The more experience you get tracking, the more successful you will be. It can be frustrating at times, but tracking reptiles or any animals for that matter can be extremely rewarding. You learn a lot about their natural history.
I hope this give you a little tidbit of information that will help you in your travels in California. There is a lot of good habitat for them. Unfortunately out of the two localities you listed, I do not have experience with. It's a little late in the year but it's still doable. However, Sidewinders seem to be generalists in terms of behavior. Check weather for each and make an educated guess.