Meeting Abstract
Many birds have evolved sonations (non-vocal acoustic signals) produced with tail or wing feathers. Within the family Tyrannidae ≈20% of the species have males with modified wing feathers hypothesized to produce sonations. Kingbirds encompass thirteen species, twelve with different outer primary feather modifications. The questions that this project aims to address are whether non-vocal signals in Kingbirds differ in 1 Acoustic characteristics, 2 The mechanism by which the sound is produced, and 3 The behavioral context. To answer these questions we compared high speed videos and sound recordings of displays in five species of Kingbirds: Eastern, Western and Tropical Kingbirds (T.tyrannus; T.verticalis; T.melancholicus) and Scissor-tailed and Fork-tailed Flycatchers (T.forficatus;T.savana). All species produced these sounds when increasing wingbeat frequency. The sound is produced by males when birds are close to each other during female-male interactions and male-male aggressive displays. In T.savana and T.forficatus the sound is also audible during interspecific aggressive attacks (e.g., against predators). Comparisons among two subspecies of T.savana showed differences in frequency during displays. Individual feathers in a wind tunnel over a range of airspeeds showed that the feathers of T.s.monachus produce sounds at a lower frequencies than those of T.s.savana matching those taken from field recordings. High speed videos of individual feathers in the wind tunnel suggest feathers make sound by fluttering of the trailing vane at the tip of the feather. We conclude that the mechanisms of sound production are similar between species of Kingbirds but that they differ in acoustic characteristics (such as frequency, intensity and duration).
