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.
Nine kinds of rattlesnakes are found in Texas, including the massasauga. Rattlesnakes usually rattle before striking, but if they are totally surprised, they may strike before rattling. Most of the rattlesnakes are active at night, when they hunt for prey such as mice, rats and rabbits.