I think the animals know something is wrong. I don’t think animals always know why though. I don’t think the fauna around me knows when a hurricane is coming during the calm before the storm. Maybe they know once the rain bands start to get really close together.
My guess is over time their sleep does become affected. One day of dark isn’t going to throw everything out of whack, but days on end will I would think. Part of their sleep cycle is for finding food and for safety, animals are more vulnerable while asleep. If they are carnivores then however their food source is reacting to the current conditions will likely affect their own reaction.
I wonder if they start migrating to try to get away from the bad air? Or, if they hunker down? I would guess the air close to the earth is better quality than 5 feet up where our faces are when we stand, assuming the animal isn’t right next to the fires.
Very difficult to think about the animals that get hurt during natural disasters. Very sad.