Are wild birds killed by cold snaps often?

Birds are affected by cold snaps, especially insectivores. Insectivores are birds that feed on insects, but when the insects are scarce due to cold and wet weather. They hid away in warm and dry places and may feed on anything they can find. Since the insects hide away, birds aren't able to feed on them and may well die in these circumstances.

Although, be aware of avian bird flu and even swine flu, So was your hands thoroughly and wear gloves. These birds may have died from being attacked from your cat. She could have played with them and shook them until they are life-less and had abandoned the birds. Also, if you still have the birds, put them in a box and try to defrost them. See if their necks nearly turn 360 degrees around, this may mean, they have hit a window or even hit another bird or car.

Disease is always a concern with wild birds, especially dead ones, because of the bird flu. You definitely don't want to handle them without wearing gloves. Birds don't freeze to death very often, so I would suspect that the most likely causes are disease or accident. If they are hit by hail stones or struck by lightning, they could just drop out of the sky. Further, many birds fly into buildings every years, so that could be another cause. In any case, it is best not to handle dead wild birds if possible.