A vole, a small rodent often confused with a common house mouse, uses a complex repertoire of vocalizations to navigate its social world. These small mammals, belonging to the genus Microtus, are not silent as they move through their grassy runways and burrows, using a combination of audible and inaudible sounds for communication. The sounds they generate are distinct and scientifically measurable. Understanding what a vole sounds like involves recognizing the high-frequency nature of their calls, many of which fall outside the range of human hearing.
The Core Vole Vocalizations
A significant portion of a vole’s acoustic communication occurs in the ultrasonic range. Adult voles can produce ultrasonic vocalizations (USVs) spanning from as low as 2.5 kHz up to 80 kHz, while the calls of pups often center in the 22 to 50 kHz range. These high-frequency sounds are not merely simple squeaks, but complex signals that often contain a strong harmonic structure. This harmonic quality gives the calls a richness that is not typical of the USVs produced by some other common rodents.
When voles produce sounds within the audible range, they can be categorized into distinct call types such as the squeal, squawk, and grind. The squeal is described as a pure, tonal sound, with a fundamental frequency that can average around 1,490 Hz in species like the water vole. This contrasts with the squawk, which is a harsher-sounding call that includes a higher degree of noise, obscuring the upper harmonics. Rapid tooth-chatter is also a recognized part of their communication repertoire.
Purpose and Context of Vole Sounds
Vole vocalizations are closely tied to specific behavioral and social contexts, communicating intent and emotional state. For instance, the high-frequency USVs play a substantial role in reproductive and social interactions. Male voles often increase the number and complexity of their USVs when they encounter an unfamiliar female, indicating a link to courtship or social investigation. Pups emit isolation-induced USVs when separated from the nest to elicit maternal retrieval.
Audible sounds are often used to mediate social conflict and establish dominance hierarchies. The sharp, abrasive tooth-chatter is used by voles to communicate aggression or an intent to fight. Conversely, lower-intensity, less complex sounds like whimpers indicate submissiveness, inhibiting further aggression. The characteristics of a call, such as its pitch and variability, function as an index of the animal’s internal state, with higher pitch associated with elevated heart rate and emotional arousal.
Voles also employ distinct alarm calls to warn others of danger. For a social species like the Harting’s vole, alarm calls are high-frequency and emitted when a predator is nearby. An unusual phenomenon is the collective, synchronized emission of alarm cries, where multiple individuals “shout” in bursts. This coordinated response suggests a sophisticated social mechanism for signaling urgent threats to the colony.
Differentiating Vole Sounds from Other Small Mammals
Identifying a vole by its sound requires comparing its acoustic profile to those of other small mammals like house mice and shrews. A key difference lies in the harmonic content of their ultrasonic calls. While vole USVs are characterized by their strong harmonic structure, the USVs of house mice are typically simpler, consisting of fewer or no harmonics.
The vocalizations of shrews present an even greater acoustic distinction from voles. Shrews are known to use a rapid, high-pitched twittering or chattering noise as a form of echolocation to navigate their environment. While both voles and shrews produce high-pitched squeaks and chirps during social interactions, the shrew’s distinctive use of ultrasonic clicks for spatial orientation is a unique acoustic signature.