During the warm months of the year, the danger of encountering rattlesnakes in certain parts of the United States cannot be overempasized. Rattlesnakes don't actually hibernate. Since they are cold-blooded, they are only be active when the temperature is warm enough. This means that in warmer parts of the country such as Arizona, or the deserts of Southern California, snakes can be seen even in the middle of the winter if the day is warm enough.
Rattlesnakes are not aggressive, however they will defend themselves if they are disturbed, startled, or stepped on.
Therefore, on warm, or hot days, a good walking stick is invaluable to use for poking around in rocky, brushy, or woody areas where a snake could be hiding.
If you see or hear a rattlesnake near the cache, leave the area. You can always come back for it another day. Don't risk getting bitten by trying to move the snake away from the cache hiding spot.
Because snakes eat rodents, they provide a very important link in the ecosystem. Please do not kill any snakes you find.