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Squirrel Rhythms: Listening to Cycles in the Body Temperature of Arctic Squirrels

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by Dr. Mark Ballora, School of Music. | ballora@psu.edu

These sonifications are based on datasets consisting of some 15,400 measurements of body temperature, measured every thirty-four minutes over the course of a year, from April 2011 to April 2012.

The sonification involves translating the data values to various ranges, and using its contour to control elements of the sound.

The sonification consists of a ringing filter, producing a brief sound something like a handbell. Each data point “rings” a bell. The iteration rate is such that the year plays over six minutes of listening time. The rate is completely arbitrary, and can be set to any time interval. When the playback is quick, like this, the result is a throbbing, buzzing sound. The male squirrels are sonified with a “brassier” sound (a sawtooth wave), while the females are sonified with “flutier” sound (a triangle wave).

The data values control the pitch and volume. At higher temperatures, the pitch is higher and louder. At low temperatures, a second layer increases in volume. This sounds like a low buzz, a bit like static or an idling engine.

Atigun female (AGS 2260)

Describes activity from 4/22/11 18:02 to 4/28/12 15:36.
Birth occurs on 5/13/11, after which the body temperature rises. This can be heard as a slight rise in pitch, which can be heard at about 0:20. Regular daily cyclic activity can be heard until about 1:35 (August 12), when the squirrel goes underground in preparation for hibernation. Torpor can be heard at 1:50 (August 15), as the body temperature drops drastically, interrupted by a spike in temperatures every few weeks. Females fall back into regular cycles immediately upon coming out of hibernation, which can be heard at 5:50 (April 15).

Atigun male (AGS 2417)

Describes activity from 4/16/11 17:21 to 4/25/12 17:09.
Males are active longer than females, not going underground until early fall. They spend a longer time underground than the females before going into hibernation, and a longer time underground after hibernation before returning above ground. Regular daily cycles can be heard until September 19 (about 2:40), when daily temperatures become less regular due the sensory deprivation underground. The drastic drop in temperatures associated with hibernation that occurs on October 10 can be heard at 2:50. Higher temperatures in irregular cycles can be heard at 5:30, when the squirrel comes out of hibernation on March 24. Regular body temperature cycles resume on April 10, at about 5:48.

Toolik female (AGS 659)

Describes activity from 4/29/11 19:09 to 5/3/12 14:51.
The birth date is not as readily apparent for the Atigun female, although it appears to be on 6/15/11, after which the body temperature rises. This slight rise in pitch, which can be heard at about 0:46, though this is not as apparent as it is in the Atigun female example. Regular daily cyclic activity can be heard until about 1:50 (August 25), when the squirrel goes underground in preparation for hibernation. Torpor can be heard at 2:04 (September 3), as the body temperature drops drastically, interrupted by a spike in temperatures every few weeks. Females fall back into regular cycles immediately upon coming out of hibernation, which can be heard at 5:45 (April 19).

Toolik male (AGS 697)

Describes activity from 4/29/11 19:09 to 5/3/12 14:51.
Males are active longer than females, not going underground until early fall. They spend a longer time underground than the females before going into hibernation, and a longer time underground after hibernation before returning above ground. Regular daily cycles can be heard until October 7 (about 2:40), when daily temperatures become less regular due the sensory deprivation underground. The drastic drop in temperatures associated with hibernation that occurs on October 31 can be heard at 3:00. Higher temperatures in irregular cycles can be heard at 5:30, when the squirrel comes out of hibernation on March 12 (5:12), and regular temperature cycles gradually resume by 5:45.

Squirrel Combinations
Datasets are combined so that two squirrel’s cycles can be heard simultaneously. (Datasets are edited so that they all span the same dates, 4/30/11 21:21 to 4/25/12 17:09). One squirrel is heard over the left stereo channel, the other is heard over the right channel. The first one listed in the file name (leftmost) is the left channel, the second one listed in the filename (rightmost) is heard in the right channel


AGS 659 Toolik adult female


AGS 697 Toolik adult male


AGS 2260 East Atigun Female


AGS 2417/9573 Atigun adult male