Gray Wolf

Howls exhibit various forms, spanning pitches from 150 to 1000 hertz. Typically, they endure 1 to 10 seconds, commencing around 350 hertz (middle F on a piano). Howls may be flat, rising, falling, or undulating in pitch. They can also feature breaks or modulations. These vocalizations serve multiple purposes, from locating pack members to attracting mates, and some observations suggest they may convey mourning for a lost pack member. Much like humans recognize callers by their distinct voices on the phone, wolves likely discern each other through their unique howls. This recording showcases diverse howl types.

Chorus howls involve one wolf initiating the howling, gradually joined by other pack members until multiple or all members are howling together. They serve to strengthen social bonds within the pack and convey territorial messages to neighboring packs. These collective vocalizations often encompass more than just howls; they may include growls, barks, squeaks, and varied howl patterns like "woa woa howls." During the breeding season, chorus howls are also used for communication with pups, potentially resulting in gender and age-related variations in pack members' vocal behavior. On average, a chorus howl lasts approximately 70 seconds.

Wolves bark in stressful contexts, for example, when near a rival pack or a competing predator such as a grizzly bear or cougar. They come in different forms such as woofs, disturbance barks (shorter in duration and lower in pitch) and agonistic barks (longer and more harmonics). Agonistic barks are often emitted by the dominant individual and often show dominance displays (e.g. tail held high). Disturbance barks are only emitted in conflict scenarios with other packs, humans, cougars or bears. Barks are also used in chorus howls but little is known as to why. Woofs apparently act as alarm signals: when a wolf emitted a woof other pack members begun to woof and displayed escape behaviors. Wolves may use different types of barks to identify different threats, and they sometimes include wavy howls with barks.

Growling is a low-frequency signal with variable sequences of growls and pauses. It includes variations like snarls, brief exhalations, and courtship growls, possibly reflecting different arousal levels. While pulsed growls aren't found in wolves, similar vocalizations in dingoes and coyotes raise questions about their classification. Short exhalations also occur during non-mating season play between the reproductive pair.

Whines, whimpers, and yelps are harmonic sounds that can incorporate separate whistle sounds, known as biphonation. Whines, lasting from tenths of a second to 1 second, typically have a mean fundamental frequency of around 500-600 Hz. These sounds are observed in various social situations, including agonistic, mating, and other social interactions often associated with submissive behavior. According to Mech (1970), wolf pups begin making vocalizations (such as whines and moans) a few days after birth, and they start howling at around one month of age.

Whimpers are brief, whine-like sounds produced in successive bursts, occurring in the same situations as whines. The primary distinction between whimpers and whines lies in their duration and the fundamental frequency of their whistles. Whimpers are shorter and feature lower whistle frequencies compared to whines. They function in contexts where a wolf is soliciting help or in distress.

Moan-like vocalizations are sounds that endure for fractions of a second to a few seconds. They have a lower pitch compared to whines, with fundamental frequencies ranging from 50 to 500 Hz. These vocalizations occur during various social interactions, including agonistic, mating, and other social contexts. While they may indicate some level of distress, they are not like whimpers which are used in contexts where the wolf is soliciting help. One analogy to humans is that moans are used when we are complaining, but don't expect any sympathy or help.

Yelp-like vocalizations are brief, high-pitched, and loud harmonic sounds that are emitted during agonistic interactions. Wolves produce yelps, seemingly to deter or halt an ongoing attack, although there isn't systematic data to fully confirm this hypothesis. They always exhibit submissive behavior while yelping. One unique type of yelp (described by Vicente Palacios studying Iberian wolves, but we have recorded the same in Yellowstone wolves) comprises a series of short yelps that modulate the fundamental frequency, creating a sound akin to laughing hyenas. These vocalizations appear to be emitted by a submissive animal to pacify a pack mate displaying dominant and aggressive behaviors. In this recording, you will hear a yelp in response to various snarls from another wolf.

A crucial element of chorus howls, the "woa call," stands out as a loud, prolonged acoustic signal. It exhibits higher pitch and frequency modulation than howls, as judged by hearing. While producing the "woa-woa howl" sound, wolves keep their mouths wide open with retracted lips throughout. This vocalization fosters increased interaction among group members compared to regular howling, resulting in frequent changes in their body positions. Notably, wolves can emit both continuous and discontinuous "woa calls."