However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing, kidney problems (such as change in the amount of urine). This is not a complete list of possible side effects.
They are more active when it is cooler, but they can and do come out of hiding at any time of the day. Here in the desert, Arizona Rattlesnakes can easily overheat and die if they cannot find a cool place to keep themselves cool.
Baby rattlesnakes usually do not feed prior to their first winter and may hibernate in adult dens. Average growth for juvenile rattlesnakes is about 10-16 cm per year. Adult growth is about 3 cm per year. Captive western rattlesnakes can live up to 30 years, but the lifespan of wild snakes is thought to be much lower.