Acoustic Monitoring Update

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Acoustic Monitoring Update

April 19, 2013

Debbie Leick shares an update, and audio recordings, from ongoing acoustic monitoring research.

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Research Update: Acoustic Monitoring 4/18/13 Debbie Leick

We completed the review of Davis Creek audio files. The acoustic recorder collected over 500 hours of sounds between February 16 and March 23. The recording schedule targeted nocturnal species, but allowed for a brief overlap into the daytime hours.

Some studies suggest the moon influences when owls vocalize. We compared owl detection days to the lunar phase, but saw no discernible trend. The table below shows the detection days versus the moon’s phases. A possible temporal pattern begins after March 15; a noticeable decrease in detections occurs here. To better understand the factors impacting vocalization phenology we will supplement this small dataset with additional monitoring.

We compiled all the owl calls to determine if they vocalize more frequently at certain times. The graph below plots all four species together.

Although we did not record between 10:00 am and 3:00 pm, the graphs show the diurnal characteristics of the northern pygmy-owl calls compared to the nocturnal nature of the great horned, northern saw-whet, and screech-owl. Knowing the best detection times and which factors influence vocalizations (weather conditions, lunar phase, temporal patterns etc.) helps determine the most appropriate times to target audio recording and file review.

blaThe table below compiles the other species detected during the audio review.

black-capped chickadee:

More audio from Davis Creek: Stellar’s Jay with Pacific Wren in background, Dusky Grouse Wing Noise, Flight Call of a Dark-eyed Junco, Western Screech Owl: Pair dueting with second bird, Pacific Wren Song

Dusky Grouse Wing Noise

Stellar Jay with Pacific Wren in Background

Flight call of a Dark-eyed Junco

Western Screech Owl

Pacific Wren

We recently installed this bat recorder near the Sheep Camp stock tank. Only one Montana bat, the spotted bat, emits sounds audible to the human ear. The other species require ultrasonic detection devices such as this bat monitor’s microphone. We also reinstalled acoustic recorders at the same monitoring locations as the three, fall migration sites. Short-distance, migrating passerines arrive daily. We anxiously await our long-distance, neotropical migrants and their nocturnal flight calls.

Previous Research Update

RVRI Research Update 03-27-13

Next Research Update

RVRI Research Update 04-30-13