NOVEL FUNCTION OF FLUTTER DISPLAY IN THE BLACK-BACKED WOODPECKER

 Reported for a diverse array of avian taxa, flght displays span a wide range of behavioral functions, most commonly associated with territoriality, courtship, or threat defense (Sutherland 1963, Mather and Robertson 1992). Picoides woodpeckers engage in a variety of flttering aerial displays, including the dramatic “butterfly flght” associated with pair bonding in the Downy (P. pubescens), Hairy (P. villosus), and Red-cockaded (P. borealis) woodpeckers (Kilham 1962, Jackson 1994). However, for many woodpecker species including the Black-backed (P. arcticus), flttering displays occur in the context of territory defense and function as a threat display to deter intruders (Lawrence 1967, Short 1971, Tremblay et al. 2016). To remain consistent with other published sources (Short 1971, Tremblay et al. 2016) we refer to this behavior as the “fltter aerial display.” During the fltter aerial display in Picoides woodpeckers, an individual engages in a quivering, mothlike flght with rapid, shallow wingbeats. The wings are extended outward in line with the body and bowed slightly downward at the distal ends. The tail is spread, revealing the outer rectrices. The flght is usually directed toward an intruder and accompanied by territorial calls.