How does a rat scream when in danger? - briefly
When threatened, a rat emits a high‑frequency squeal that may be heard by humans as a sharp chirp. The sound results from rapid laryngeal muscle contractions, producing frequencies up to about 50 kHz.
How does a rat scream when in danger? - in detail
Rats emit a high‑frequency alarm call when they perceive an immediate threat. The sound originates from rapid vibration of the vocal folds in the larynx, driven by a sudden burst of airflow from the diaphragm. This produces a broadband ultrasonic pulse ranging from 20 to 50 kHz, often accompanied by a lower‑frequency component (4–8 kHz) that can be heard by human observers.
The call is triggered by activation of the amygdala and periaqueductal gray, which process danger signals from the auditory and somatosensory systems. Upon detection of a predator, a brief, involuntary motor pattern—known as the “panic scream”—is executed. The motor pattern includes:
- Immediate closure of the glottis followed by rapid opening, creating a pressure surge.
- Contraction of the intercostal muscles to force air through the narrowed glottis.
- Simultaneous activation of neck and jaw muscles to modulate the acoustic spectrum.
Acoustically, the ultrasonic portion travels efficiently through dense vegetation and small openings, allowing conspecifics to receive the warning even when visual cues are blocked. The lower‑frequency component serves as a “contact call” for nearby individuals that may not detect ultrasonic frequencies.
Behaviorally, the alarm call initiates several defensive responses in the colony:
- Freezing or fleeing of nearby rats.
- Release of stress hormones (cortisol, adrenaline) that heighten vigilance.
- Recruitment of other members to the source of danger, increasing mobbing efficiency.
Neurophysiological recordings show that the call is associated with a spike in activity of the nucleus retroambiguus, which coordinates the laryngeal muscles. After the call, a refractory period of 2–3 seconds prevents immediate repetition, limiting acoustic clutter.
In laboratory settings, playback of recorded alarm calls elicits the same avoidance behavior, confirming the signal’s functional role as a predator alert. The combination of ultrasonic and audible frequencies, rapid onset, and stereotyped motor pattern constitutes the rat’s primary acoustic alarm system when faced with danger.