Grand jury is so named because traditionally it has greater number of jurors than trial jury, called a petit jury (from the French word petit meaning small).
Although mice tend to come out in the night when most of the occupants of the house are asleep or immobile. This allows them to stealthily infiltrate any of your food bags, crumbs etc. During the day time, mice will normally not come out, but if opportunities exist then they surely can.
If birds stay out during the daytime and the bats come out at night, then they both get to eat without fighting. The animals that only come out at night are called nocturnal animals, and the animals that only come out during the day are called diurnal.