The sudden, sharp sounds piercing the darkness can be startling, leading many people to wonder what creatures are responsible for the loud vocalizations heard after sunset. While a variety of animals are active at night, a distinct, harsh noise known as a “screech” is typically an avian phenomenon. These calls are not the gentle hoots commonly associated with owls, but rather an intense, raspy sound that carries a great distance across the quiet nocturnal landscape. Understanding which birds produce these calls and why they are so loud demystifies the experience and helps identify the secretive wildlife.
Key Species That Screech
The bird most reliably identified as the source of a true screech is the Barn Owl (Tyto alba). Unlike most other owls that produce a rhythmic hooting sound, the Barn Owl’s primary vocalization is a drawn-out, hissing shriek that lasts for about two seconds. This raspy scream is common in their habitat, which frequently includes open fields, barns, and abandoned structures.
Male Barn Owls use this piercing call frequently as a form of communication, often while flying, to beckon a female to inspect a potential nest site. The volume of the screech is necessary for the sound to travel over the large open areas where these owls hunt. The Eastern Screech-Owl (Megascops asio) also contributes to the confusion, despite its name being misleading. This smaller owl’s most common vocalizations are a descending, horse-like whinny or an even-pitched trill. However, its distress calls or the whinnying used to defend territory can be sharp enough to be described as a screech by listeners.
Why Nocturnal Birds Vocalize So Loudly
The heightened volume of nocturnal bird calls is an adaptation for long-distance communication in the dark. Sound travels farther and more clearly at night due to the absence of daytime wind and thermal turbulence, making a loud call an effective tool. These vocalizations serve specific functions related to survival and reproduction.
One purpose is territorial defense, where an intense screech warns potential competitors to stay away from a hunting or nesting area. The sound acts as a sonic fence, broadcasting the bird’s claim over a specific patch of habitat.
Another function is mate attraction and pair bonding. Males of many species produce loud, ritualistic calls to advertise their presence and quality to females.
Loud calls can also be a form of alarm or distress when an owl or nightjar feels threatened by a predator or when nestlings are begging for food. A young Barn Owl, for instance, emits a loud hissing sound when disturbed, which is part of a defensive display designed to startle an intruder.
How to Differentiate a Screech from Other Night Calls
The harsh, piercing sound of an avian screech is frequently mistaken for the cries of nocturnal mammals. A true bird screech, such as that from a Barn Owl, is typically a single, sustained, unmodulated shriek. It lacks the rhythmic pattern of a typical hoot and tends to be very brief, lasting only a few seconds before cutting off abruptly.
In contrast, the most common source of confusion is the Red Fox, whose vixen’s scream is often described as sounding like a human wail. Fox vocalizations are usually more variable, with a higher degree of pitch change and a more agonized quality than the mechanical, sustained sound of an owl’s screech. Determining if the noise is a clean, sharp avian call or a more complex, fluctuating mammalian cry relies on listening for the consistency and duration of the sound.
Safe Observation and Identification Techniques
Identifying the source of a nocturnal call requires careful listening and respecting the bird’s natural behavior. Modern technology offers several aids, including sound identification applications that can record a call and cross-reference it with a library of known bird vocalizations. Consulting these audio databases allows for a direct comparison of the distinct Barn Owl shriek or the Eastern Screech-Owl’s whinny with the sound heard in the field.
For those attempting visual confirmation, observation should be done with minimal disturbance. Using a flashlight with a red filter is recommended, as red light is less disruptive to a nocturnal bird’s vision than white light. Never approach a nest or roosting site, and always stay on established paths to avoid trampling vegetation or inadvertently disturbing a hidden bird. Many owls and nightjars are masters of camouflage and often remain silent when they sense human presence.