A cool morning, so loaded up the gear and went into the field to see what birds are around. Preening was top of the list behavior today. Studies on multiple species have shown that birds spend an average of more than 9% of each day on maintenance behaviors, with more than 92% of that time spent preening. Preening involves the use of the bill to position feathers, interlock feather barbules that have become separated, clean plumage, and keep ectoparasites in check. Though primarily an individual function, preening can also be a social activity involving two or more birds, which is known as allopreening. Some birds will also use their feet in an action termed as scratch-preening which is usually applied to the head. Because feathers are critical to a bird's survival—contributing as they do to insulation, waterproofing and aerodynamic flight — birds spend a great deal of time maintaining them.