For example, a gull whose most efficient loiter airspeed was 22 mph could fly at anything between 15 and 28 mph without increasing its metabolic rate more than 15 percent. Most birds fly below 500 feet except during migration.
Flying at night is not unusual for Silver Gulls – they are known to feed at dusk, catching insects around water sources and lights. ... Flying Foxes can be distinguished from the gulls as the bats are unlikely to be circling around the Bridge in the same way as the gulls do, as there is no food for them there.Aug 25, 2010