The social context of a territorial dispute differentially influences the way individuals in breeding pairs coordinate their aggressive tactics.
Published in: Behavioral ecology and sociobiology
Eric R. Schuppe*, Gloria D. Sanin, and Matthew J. Fuxjager
Department of Biology, Wake Forest University, Winston-Salem, NC, 27109, USA
*Corresponding Author
Email:
Electronic supplementary material:
Recordings of ambient downy woodpecker drumming
Briefly at the onset of the study, we located male and female downy woodpeckers throughout woodlands and greenways in Forsyth County, North Carolina, USA (see methods) and recorded instances of spontaneous drumming. Recordings were collected in the morning between 06:00 and 10:00 using a directional microphone (Sennheiser ME66) attached to a Tascam recorder (model # HD-P2; sampling frequency = 44.1 kHz). We utilized the same sampling methodology described in the paper (see Animals) to ensure we did not record from the same individual more than once. We used Audacity (v. 2.0.6 ) to visualize and quantify elements of drums, including (i) duration of the drum (s), (ii) number of beats per drum, and (iii) time between drum bouts (Table 1).
Table 1. Characterization of acoustic parameters within a random subset of animals (n = 20) within our study population.
Mean ± SDDrum length (s) / 0.91 ± 0.18
Number of beats / 15.10 ± 2.97
Time between drumming bouts (s) / 7.33 ± 6.70
Beat cadence (s) / 0.064 ± 0.002
Previous studies indicate that drums are sexually monomorphic, and to verify this in our study population we compared drums from identified males and females (Table 2). To analyze differences in acoustic elements we utilized several linear mixed models with sex as a fixed factor and individual identity as a random factor.
Table 2. Assessment of differences in the acoustic parameters of male and female downy woodpecker drums during the territorial establishment period. Analyses were performed on a subset where observers could visually confirm the sex of the bird.
Male(n = 4) / Female
(n = 4)
Mean ± SD / Mean ± SD / Fdf / p
Drum length (s) / 0.88 ± 0.23 / 0.91 ± 0.21 / F1,5.37=0.17 / 0.69
Number of beats / 14.22 ± 4.42 / 15.11 ± 3.26 / F1,5.31=0.03 / 0.88
Time between drumming bouts (s) / 6.02 ± 3.98 / 7.15 ± 6.88 / F1,4.93=0.59 / 0.48
Figure 1. Wave form diagrams of a representative spontaneous downy woodpecker drum (A) used to create long (B, 19 beat) and short (C, 11 beat) drum stimuli. Each spike indicates a beat wherein the woodpecker’s beak made contact with a tree or snag. The space between two spikes represents the beat cadence.