How Does a Fluffy Squirrel Produce Sound?
If you’ve ever wondered how the flute squirrel makes its alarm calls, you’re not alone. Many ground squirrels produce an ultrasonic alarm call that is so high-pitched that we can’t hear it. Here’s how to recognize whether the noise is audible or ultrasonic. You may be surprised to find out that you can hear the same sound coming from different squirrels.
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Ground squirrels make an alarm call so high pitched that we cannot hear it
It’s possible that ground squirrels’ ultrasonic alarm calls are the cause of the bats’ ability to find their prey. Ground squirrels use this type of alarm call to alert other squirrels to their presence. This type of sound is so high pitched that we simply can’t hear it, but bats have been using this kind of call for centuries. This study was conducted to learn if ground squirrels make these alarm calls and if so, what is the reason for it?
In 1966, the first published spectrographic analyses of ground squirrels’ alarm calls were published. The authors recorded squirrels using the same equipment. They used a small unidirectional microphone and a sound spot called the Electrovoice-644. The sound spot had a frequency response of 0.05 to 12 kHz, and was attached to a portable tape recorder.
The sound of a squirrel’s alarm call is often similar to another squirrel’s alarm call, but in fact it can be hard to distinguish between a male and a female. Males will chase female squirrels around the forest in order to attract a mate. The male will also become territorial and vocal during the chase. These two methods can be very helpful in attracting other squirrels.
Detecting an ultrasonic call by a ground squirrel
Richardson’s ground squirrels use an ultrasonic alarm call to alert other squirrels of predators. They have distinct spectral characteristics that allow them to selectively beam these alarms to their receivers. The sound produced by a ground squirrel is low-pitched and often sounds like holes, so if you can hear it, you are most likely hearing a Richardson’s ground squirrel.
While its use isn’t well understood, there is evidence that these signals may actually be beneficial to squirrels. They are unable to be heard by many rodent predators, and they may only serve to warn their conspecifics of danger. Ultrasounds also have a shorter range than audible sounds, so they may be used as a secret warning signal for animals far away from their active space.
Although ground squirrels are arboreal and semi-communal, they do exhibit similar behavior when trapped. These animals usually group their burrows closely together and have a similar frequency and pitch. They also use ultrasonic calls as a signal to attract other males. In the presence of other males, these ground squirrels may be easily tempted to enter their burrows.
Detecting an audible alarm call by a flute squirrel
The flute squirrel is not alone in using an audible alarm call to alert other squirrels of a threat. The flute squirrel is one of the few species that produces both vocal and tail alarms. Both types of calls are distinctly different. The vocal alarm, called a kuk, is a generic signal that a squirrel makes when something disturbs it. Quaas, on the other hand, are used to alert the squirrel to aerial threats while a kuk is typically used to warn terrestrial predators.
The reason for the different calls is that the high pitch of the calls elicit an alarm response in other animals, but the whisper calls indicate a lower threat level, meaning that the frightened animal is less dangerous. As a result, whisper calls evolved to help ground squirrels communicate with their neighbors. Although this method has been observed in other species, it’s unclear if this technique is effective in a human-to-human situation.
A study conducted at the White Mountain Research Station in Maine found that a golden-mantled ground squirrel, a flute squirrel, and a golden-bellied marmot shared a mutual benefit in heeding the alarm calls of each other. Nonetheless, the naturalists’ findings were not enough to convince their colleagues of this connection. They resorted to experimental research to verify the observation.
Jessica Watson is a PHD holder from the University of Washington. She studied behavior and interaction between squirrels and has presented her research in several wildlife conferences including TWS Annual Conference in Winnipeg.