You are seven times more likely to have a bird strike at night than during the day. Many migratory species wait until nightfall and then ride the winds at altitude to get a higher groundspeed.
Take a look at some of the migratory bird paths and altitudes available in publications like "Sharing the Skies" and the information is very interesting.
Also the higher altitudes strikes usually involve larger birds and in flocks.
I would add a big
"If" to this
The probability is also tied to the probability of an aircraft occupying the exact same airspace at the time.
The majority of the multiple engine bird strikes occur during the day at very low altitudes in line with runway headings,