The acoustic world of mice is far more complex than the occasional squeak, involving a sophisticated combination of physical noises and vocal communication that provides deep insight into their presence and behavior. Understanding the sounds mice produce is not merely about confirming an unseen animal’s location, but about interpreting a range of signals that reflect their immediate activity, emotional state, and social interactions. These tiny animals navigate their environment using a rich acoustic repertoire, much of which remains inaccessible to the unaided human ear. Deciphering these noises serves as a primary method for determining their activities and understanding their specialized biology.
Sounds Humans Can Hear
The most common signs of mouse presence are the physical sounds resulting from their movement and maintenance activities within a structure. These structural noises include the rapid, light scurrying or scampering sounds as mice travel along baseboards or inside wall voids, which is characteristic of their quick, small stride. A distinct scratching noise is often produced when their claws grip a surface while climbing or digging through insulation and drywall to create pathways or nesting areas.
Another highly identifiable sound is the repetitive gnawing noise, which is a necessity for these rodents whose incisor teeth grow continuously. Mice must chew on various materials, such as wood, plastic, or wires, to wear down their teeth, generating a discernible grinding sound, often at night. Audible vocalizations, separate from these physical noises, include high-pitched squeaks and chirps that occasionally fall within the range of human hearing, typically below 20 kilohertz (kHz).
The Social Function of Vocalizations
The audible vocalizations that humans can perceive are closely linked to immediate emotional states and short-distance communication, serving as direct social signals. High-pitched, persistent squeaks often function as distress calls, indicating pain, fear, or a sense of being trapped. These are generally louder and more prolonged, designed to convey an urgent message.
Shorter, more sporadic chirps and softer squeaks are used for non-threatening social interactions, acting as contact calls between individuals in close proximity. For instance, a mother mouse may use soft chirping to communicate with her pups, and adults use various tones during social investigation or play. The pitch and duration of these audible calls can vary significantly, providing context to the receiver about the sender’s current intent.
Ultrasonic Communication
Beyond the range of human hearing, which typically cuts off around 20 kHz, mice engage in complex acoustic signaling through ultrasonic vocalizations (USVs). These high-frequency sounds primarily occur between 30 and 120 kHz and are the foundation of their communication system. USVs are utilized in specific social contexts, most notably for courtship and territorial disputes.
During courtship, male mice produce elaborate, complex USV sequences, often referred to as “mouse song,” to attract females and stimulate mating receptivity. The structure and frequency modulations of these calls convey information about the male’s fitness and identity. Another primary function is the isolation call: when a pup is separated from its mother, it emits USVs, typically around 40 kHz, which prompt the mother to locate and retrieve her offspring. USVs associated with non-aversive situations tend to be higher in frequency, while lower-frequency USVs can be emitted during stressful exploratory situations.
Pinpointing Location Based on Sound
The sounds a mouse makes are highly indicative of its location and activity patterns, offering a practical way to locate their presence. Mice are nocturnal, meaning the sounds of scurrying and gnawing are most prevalent at night, often right after sunset or just before sunrise when the house is quiet. Hearing quick, rhythmic scratching or scuttling sounds originating from inside a wall or ceiling void suggests a travel route or nesting site within the structural gaps.
The location of the noise can help distinguish the type of activity. Gnawing sounds heard near floor level or behind appliances often indicate the creation of an entry point or the search for food sources. Since mice tend to be active at ground level, noises heard in basement areas, behind baseboards, or under floors are strong indicators of their presence. A sound’s volume and consistency also provide clues: a faint, sporadic noise might be a lone explorer, whereas persistent, louder activity from a specific location suggests a well-established nest.