It seems cold for them to be moving around. Where are you finding them?

Are they found only within the shade of oak-covered hillsides such as those at HREC or can I plant them in my northern sacramento yard, under a tree in my irrigated meadow and watch them successfully grow and blossom? I'd expect them not to blossom in the triple digit heat of the summer, right?

Answer to question about rattlesnakes - you have to think like a snake and look for any crervice or cover taht will protect them from winter rains, flooding, cold, and predators. So ...usually rock crevices, rip rap rock along roads and streams, sometimes man-made junk piles.  
 
Answer to question about Mission Bells - no they won't grow well naturally in the hot Central Valley. However, they wither up in early summer to regrow from the bulb the next winter, so maybe yes in pots or protected areas.