What would explain this odd animal behavior?

I walk out to my deck and noticed 5 birds around my feeder and two sitting on the feeder. They were all still looking away from me. I would notice they glanced at me slightly but continued to look away from me. Usually they would fly away and then come back if I look busy.

But then I noticed there was no singing. Not any one of them or any birds in the woods, behind my home. That was the direction they were looking. Even the squirrel in the woods was standing and looking in the same direction. I can usually hear the squirrels running about in the fallen leaves but there wasn’t a sound. I saw no predators. They stayed like that for about 10 minutes and it didn’t mattered that I moved about. They were not paying me any mind. Just standing like frozen little statues. Then I hear one bird chirping in some tree and then everyone resumes what they were doing. Flying, eating or running about. I thought maybe there was a fire somewhere. What do you think it was?

Could they be sensing a quake about to happen? Strange they would just freeze where they were. No attempt to hide or even flee my presence.