Anthropogenic Noise on the Range
Anthropogenic Noise interrupts Painted Bunting
The above image is a spectrogram of a Painted Bunting (the evenly spaced vertical squiggles) that was interrupted by engine noise from an aircraft overhead. The ripples are the aircraft - the frequencies get higher as the aircraft approaches. When the frequencies get up into the range of the bunting call he stops calling, until they subside as the aircraft gets further away. This sort of thing happens several times a day in this area. While not exactly remote, this site is still 5 miles from an interstate or even a state highway.
How does environmental noise influence breeding success of birds and other vocal species?
I built an awning over my patio last year out of steel tubing. Across the front edge is a piece of 1 1/4” square tubing about 24’ long that is open on both ends because I’m too cheap to spend 25 cents on plastic caps. A green/grey tree frog has appropriated that tubing to be his sovereign territory and declares as much to the world from just inside the end of said tubing. I’d really like to know what the other tree frogs in the neighborhood think when mine cranks up his vocal cords from inside his custom-built amplifier. His call is deafening if you are standing too close. The acoustic masking from the nearby air conditioner is simply no match for those vociferous vocalizations. I suspect he even scares the predators away!
Do vocal species select habitats based on soundscape traits?
This raucous ranid got me wondering about how animals that depend on vocalizations for conspecific interactions select their habitat. Is my frog selecting his perch based on acoustics or because steel tubing is basically an impenetrable defense against almost anything? It is hard to argue that steel tubing isn’t a pretty safe place to hang out. I suspect he might have been looking for a secure spot to spend the evening, discovered the anuran amplification properties and took advantage of them.
What about Bob?
One of the sites where I commonly see detections for Northern Bobwhite is not what I’d call great habitat - or even good. It is mostly three-awn and scattered shrubs. It might be easy for the chicks to get around in, but there aren’t any chicks when the survey takes place. Is it possible that the soundscape is just better suited for bobwhites in that area because of the lower density of brush? They may use other parts of the property during different times of the year but prefer this area during breeding season.
Soundscapes and wildlife management
If there are high levels of oil/gas production or wind farm activities in an area, does it even make sense to attempt to manage for some of these species for which vocalizations are so important? How does the frequency range of energy production activities overlap with that of Northern Bobwhite - or any of the other vocal species?
“Always more questions than answers, there are.” – Yoda