Ecological Archives A017-086-A2

Natalie T. Boelman, Gregory P. Asner, Patrick J. Hart, and Roberta E. Martin. 2007. Multi-trophic invasion resistance in Hawaii: bioacoustics, field surveys, and airborne remote sensing. Ecological Applications 17:2137–2144.

Appendix B. Supplementary figures showing bioacoustic spectra of avian vocalizations and abundance of native and exotic birds by habitat.


   FIG. B1. Bioacoustic spectra of avian vocalizations from digital audio recordings, showing sound level intensity from 2000–8000 Hz. Recordings were acquired (a) directly after the dawn chorus (7–9 am local time), and (b) at mid-day (12–2 pm). Bioacoustic indices of avian abundance (Figs. 1, 2c, 3a) were calculated from the morning spectra shown in (a) at the time of day during which birds are most vocal. Forest sites are indicated in blue, woodland sites are indicated in green, savanna sites are shown in red and shrubland sites are indicated by cyan. Due to high wind conditions, there was no mid-day data collected for the Exotic gradient’s shrubland site. Sites along the Native and Exotic gradients are indicated by solid and dashed lines, respectively. Each site spectra represents the average of three station spectra.




   FIG. B2. Abundance of native (blue shades) and exotic (green shades) avian species at each site along Native and Exotic gradients. Each site value represents the average of three station values.

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