I don't have a particular season that's worse, or better.
We have more hawks in spring and summer, bet they get very few of our birds. One bantam pullet this summer only. She's missed, but at least only one.
Since we have a very secure coop, our worst losses are daytime; a very occasional missing bird.
Canines!!! Our worst, a few years ago, in spring to a sick mangy fox, ten nice hens one afternoon. He chose actively laying hens only, and came back for refills.
Then, this spring, our own dog, when our fence failed, 28(!!!) birds, awful!
Good security at night is so important!
Because of our farm layout, electric poultry fencing can't be set up around the coop. If possible, it's the way to go for ground predators.
Mary