BEH (Behavior):  The following behavior categories (with numeric codes) are recognized:
        Forage. (10)  Actively searching for food; usually characterized by small movements of the head.  Whenever possible, the following subdivisiions of foraging are recognized.
        Glean: (12)  Picking insects from the surface of a substrate, usually leaves or bark.
        Hawk:  (13)  Attemping to capture an insect from the air.  Record perch from which it flew.
        Hover:  (14)  Hovering in the air to forage, usually from a leaf.
        Probe:  (15)  A probe is a forage under or within a substrate.
        Drill:  (16)  Creating a hole for foraging (e.g. woodpeckers)
        Feeding:  (20)  Manipulating a food item.
        Inactive:  (25)  No overt behavior except very small movements of the body.  This must be preceded by a move > 1 m or last at least 30 seconds to be recorded.
        Sing:  (30)  Loud, repetitive, complex vocalization usually given by males during the breeding season.
        Call:  (35)  Any vocalization that is not a song.
        Flush:  (40)  When a bird flies in response to the observer or a warning call of another bird.  Location is where the bird lands not where it flushes from.
        Preen:  (45)  Manipulating feathers, stretching, ruffling feathers, and other comfort movements.

        Social Interactions.  These are subdivided as follows:
        Courtship:  (51)  Male-female interactions related to breeding, e.g. allopreening, displays, courtship feeding.
        Parental care:  (52)  Carrying food or fecal sacs.
        Begging:  (53)  Young birds soliciting food through calls and postures.
        Aggression:  (54)  Fighting, chasing, displaying between species or between members of the same sex within a species.
        Miscellaneous:  (60)  Only rarely will an activity occur which doesn't fit the above categories:  describe it.

Found missing from this list (April 9, 2019):
50 -- Social Interaction
55 -- Carrying Food