Playback Experiments

Once the basic experiments with the sonic net had concluded, we started playback experiments. These involved setting up a speaker with an iPod to play either the alarm call of a tufted titmouse or the main call of an eastern screech owl (an ethereal sound someone likened to the call of a mournful ghost cat). We would then film and record the reactions of the birds at each feeder so that we could later analyze their behavior and vocalizations. It was hard at first to describe the actions of the birds while coordinating the filming, but we all figured it out quickly after a day of practice. The surprising thing was that on the surface, it often seemed like there wasn’t a change in behavior. Perhaps the playback would start and the bird on the feeder wouldn’t leave, or more birds would come and feed. Or we would unknowingly hit the play button just as a bird was leaving the feeder, and no birds would return. Some days were busy days, which meant more work on our transcriptions later. Other days (though this was rare) we wouldn’t get a single bird at one of the feeders.

As with our earlier field observations, these expeditions to the field sites offered a better glimpse into the interactive behavior of birds. We watched chickadees and titmice mob the speaker (and later on the stuffed screech owl we used for the visual predator experiment). We got to see a pair of Carolina wrens cartwheeling through the woods, possibly in the middle of a mating duet or territory rivalry. More than once all of the birds went quiet and still, and moments later we would see a red tailed hawk or Cooper’s hawk sailing above or through the pines. We spotted a beautiful male indigo bunting and a bright hooded warbler at the most remote field site.