How do rats scream when threatened? - briefly
When faced with danger, rats emit a sharp, high‑frequency vocalization, typically around 20–30 kHz, that sounds like a brief, high‑pitched squeal to human ears. The alarm call results from rapid contraction of the laryngeal muscles and alerts nearby conspecifics.
How do rats scream when threatened? - in detail
Rats emit a distinctive distress vocalization when they perceive a threat. The sound is produced by rapid vibration of the laryngeal membranes, driven by sudden increases in subglottal pressure. In most cases the call contains an ultrasonic component (≈ 20–50 kHz) that is invisible to human hearing, accompanied by a lower‑frequency segment (≈ 5–10 kHz) that can be heard as a sharp squeal.
Acoustic parameters are consistent across studies:
- Peak frequency: 20–45 kHz (ultrasonic) plus a 6–9 kHz audible peak.
- Duration: 30–150 ms per syllable, often emitted in series of 3–7 calls.
- Amplitude: 70–80 dB SPL at 10 cm for the audible component; ultrasonic intensity reaches 90 dB SPL.
- Frequency modulation: rapid upward sweep followed by a brief plateau, then a sharp decline.
The physiological cascade begins with activation of the sympathetic nervous system. Adrenergic signaling contracts the intercostal muscles, raising intrathoracic pressure. The laryngeal adductor muscles close the glottis, forcing air through a narrowed glottal slit, which generates the high‑frequency oscillations. The ultrasonic portion is facilitated by the thin, tense vocal folds of the rat, allowing vibration at frequencies far above those of larger mammals.
Behavioral triggers include:
- Direct predator contact or visual cue of a predator silhouette.
- Physical restraint, tail pinching, or other painful stimuli.
- Sudden exposure to loud, aversive noises.
- Social isolation combined with heightened stress hormones.
Laboratory recordings employ ultrasonic microphones (20–100 kHz bandwidth) and high‑speed spectrographic analysis. Typical protocols place the animal in a sound‑attenuated chamber, introduce a threat stimulus, and capture vocal output with a sampling rate of ≥250 kHz. Data consistently show a burst of ultrasonic calls within 100 ms of threat onset, followed by a series of lower‑frequency squeaks if the stimulus persists.
The emitted signal serves two primary functions. First, it alerts nearby conspecifics, prompting avoidance or collective vigilance. Second, the sudden, high‑intensity sound can startle a predator, increasing the victim’s chance of escape. The dual‑frequency structure ensures detection by both rat auditory systems (sensitive to ultrasound) and by predators capable of hearing lower frequencies.