Predominant vocalization of young is the Beg, beginning just prior to or just after hatching. A repeated, broad-band (1–9 kHz), relatively long call (0.5–0.8 s), with moderate intercall interval (0.2–0.3 s) and very distinct harmonic structure; a repetitive, screea, screea, screea that becomes slightly lower in frequency with age. Early in development (first week), structure of call strongly resembles that of adult Wail (see below), but gradually becomes noisier and harsher, resembling adult cack (see below). Calls of individuals have a high index of similarity within calling bouts (>90%), but calls from same individual at different ages are initially less similar to each other than those of different individuals at same age (NJC); probably a function of physical changes in syrinx due to growth. Call structure begins to stabilize about 7 d for male and 9 d for female (NJC). Sex differences of adults (see below) also present in young (NJC).
Young utter Beg during feeding or in presence of adults, especially upon latter's arrival at eyrie. Muffled, closed-mouth version given while visually searching for absent parents. When food is offered by adult, call resembles Whine (see below); taking of food often accompanied by a singular resonant yack from donor, recipient, or both (Herbert and Herbert 1965, Weaver and Cade 1978, Hustler 1983, Marchant and Higgins 1993).
In wild, young will hiss when approached by humans and other animals at 2–3 wk old; in captivity, presence/timing of this response dependent on rearing. By 3–4 wk young have acquired cack vocalization (Ingram and Salmon 1930), and use a very loud, demanding version of adult Wail to solicit food (Cade 1960, Hustler 1983), the sound carrying to human ear over distances of 1.5–2.0 km. Older nestlings and immatures grunt; a singular, deep, ugh when surprised at close quarters (references in Cramp and Simmons 1980a, NJC).
No evidence of vocal learning. Birds raised in isolation exhibit full repertoire of calls.
Most vocalizations associated with aspects of reproductive behavior. Usually quiet away from eyrie, except for intra- and interspecific aggressive encounters. Repertoire of male and female similar, also to other falcon species, but relative frequency and context of vocalizations vary with gender and species. No geographic differences noted among wild birds of 4 subspecies observed in captivity (F. p. tundrius, F. p. pealei, F. p. anatum, F. p. brookei; Wrege and Cade 1977).
Quantitative sex differences occur in sound frequency and in power spectra; male calls approximately 0.2 kHz higher than female, and male calls often encompass a broader range of frequencies and have more distinct harmonic structure (see sonograms in Cramp and Simmons 1980a). Male and female cack vocalizations can be distinguished with about 90% accuracy (Telford 1996).
Individual recognition of cack vocalizations is possible with 72–90% accuracy on average, and recognition of calls is highly repeatable across years and observers. Frequency characteristics appear most useful for distinguishing calls, as opposed to temporal characteristics or patterns of frequency modulation within calls (Telford 1996). Historical emphasis on phonetic descriptions of calls has created some confusion regarding categorization of calls, but most Peregrine vocalizations can be placed in 1 of 4 categories based on structure: cack, Chitter, eechip, and Wail. With exception of cack, each vocalization is used in multiple contexts. Variation in intensity reflected in changes in call structure and may signal both quantitative and qualitative changes in motivation (Wrege and Cade 1977). See Cramp and Simmons 1980a for variations on phonetic descriptions of calls.
Cack. Repeated, relatively short (0.15 s), broad-band (1–9 kHz), harmonic call with moderate intercall interval (0.1–0.2 s); a harsh kak kak kak kak kak, often repeated incessantly. Call of female tends to be more rapid, with a shorter intercall interval than male (see sonograms in Cramp and Simmons 1980a). Given in alarm and in conjunction with nest defense. May increase in speed and pitch with increasing intensity (Herbert and Herbert 1965), but speed of calling decreases when actually attacking; upon contact, call degrades into a shrill, fragmented, kaa-aa-ack, kaa-aa-ack (Cade 1960, Herbert and Herbert 1965).
Chitter. Repeated, very short (0.02 s), broad-band (0–5 kHz), harmonic call with very short (0–0.02 s) intercall interval; a feverish chi chi chi chi chi occurring in bursts of 5–12 repetitions or continual up to several seconds). In wild and captivity, most frequently given by male prior to or during copulation (in association with Hitched-Wing Display) and during copulation (Nelson 1977b, Wrege and Cade 1977, Hustler 1983); occasionally given by either sex in alarm (Nelson 1977b, Marchant and Higgins 1993). In captivity, may be given by either sex during agonistic Head-Low Bow Display, when forcing mate off eggs, or by female when forcing Food Transfer. In cases of extreme alarm, degrades into Scream (TJC, NJC).
Eechip. Repeated, 3-part call of variable but relatively long duration (0.25–0.8 s) and intercall interval (0.1–0.8 s). In its most complete form, a sharp, deliberate, ku ee chip, ku ee chip from which either the ku or ee or both may be dropped. The ku, which contains the least energy of the 3 elements, covers a lower range of frequencies (0–4 kHz), has an indistinct harmonic structure, and is about 0.05 s in duration. The ee, which follows within 0.01 s (when present), is a rising, single-band, frequency- and- amplitude-modulated sound that begins at about 4.5 kHz, plateaus about 5 kHz, and is about 0.08 s in duration. The chip (or chup of female) contains most energy, covers broadest range of frequencies (1–6 kHz), has distinct harmonic structure, and has longest duration (0.1 s; NJC).
Used by both sexes in wild and captive birds in association with various forms of Head-Low Bow Display, within the context of Individual and Mutual Ledge displays, and during Food Transfers. In captive birds, also given by male during or immediately following copulation. In wild birds, given during aerial encounters with conspecific intruders around nest site; exact motivation unclear (Cade 1960, Nelson 1977b, Telford 1996). With increasing proximity to mate, call increases in speed and intensity and ku and ee syllables tend to be dropped. As intensity decreases, call may degrade to Peeping, in which only dominant frequency of the chip remains (2.0–4.0 kHz), slightly attenuated to almost continual; may be interspersed with ku or chip elements. Peeping generally associated with Billing and/or termination of Ledge Display (Wrege and Cade 1977).
Wail. Continual or repeated, relatively long call (0.4–2.0 s), with irregular intercall interval (0.1 s to several min). Less noisy with more distinct harmonic structure than other calls and more even distribution of energy across frequencies (1–6 kHz), rising slightly in frequency over time; a querulous waiiiik . Has widest variety of forms/contexts of all calls; forms include Wail, Whine, and Beg (see above).
The Wail appears in several contexts: Food Wail, Agonistic Wail, Copulatory Wail, and Advertisement Wail. In captive and wild birds, most common is Food Wail, given by either sex prior to Food Transfer. In this context, calls tend to be shorter (0.5 s), more frequent, and more regularly spaced, with energy concentrated at 2–3 frequencies. Less common is Agonistic Wail; in captivity, given by either sex in association with territorial behavior or by female when signaling male to move. In wild, associated with self-defense or defense of food (mantling; Nelson 1977b, Hustler 1983). In this context, call tends to be slightly longer (0.7 s), with energy distributed across 3–4 frequencies; may precede a cack or Scream. Copulatory Wail is given by captive female during coition (Wrege and Cade 1977); not documented in wild birds. This form is longer (1.0 s), with energy distributed across 3–4 frequencies, repeated 2–4 times (i.e., until copulation attempt terminated). Advertisement Wail is given primarily by male, spontaneously, apparently randomly, and usually in absence of mate (Carlier 1995) or intruders (Nelson 1977b); frequently heard after nest failure (TJC). No quantitative information, but qualitatively less intense than other forms. Whine is most structurally and contextually distinct of this group of calls. Typically consists of single band about 4 kHz, extremely attenuated (2–3 s), rising slightly in frequency and amplitude. In wild and captive birds, given by female during solicitation; a more abbreviated version occasionally given prior to Food Transfer. Beg (see description above) sometimes given by wild adult female immediately before Food Transfer from male.
Most calls limited to the reproductive period, except cack and Agonistic Wail, either of which may be given in response to individual alarm. Even cack, to extent that it functions in territorial defense rather than self-defense, is probably more common during breeding. Phenology of vocalizations follows seasonal ontogeny of reproductive behaviors. Chronologically, Wail may occur first, given its function in advertisement, followed by cack and eechip, in association with territorial defense and courtship. Frequency of nest defense, and therefore territorial vocalizations, highest during courtship and decreases significantly as reproduction progresses (Court 1986). Frequency of eechip in reproductive displays, however, increases steadily throughout breeding, as does Wail (Carlier 1995), in association with Food Transfers. Chitter, Whine, and Copulatory Wail are most prevalent the month preceding egg-laying, in association with solicitation and copulation (Wrege and Cade 1977).
Not specifically documented. Territorial vocalizations (cack, eechip) occur in response to intruders and activities of other animals at any time. In captive birds, vocalizations associated with reproductive displays most common in 4 h following sunrise and preceding sunset (Wrege and Cade 1977). Birds breeding at higher latitudes show less distinct temporal patterns.
Places Of Vocalizing
Site of vocalizations determined by site of behavior, usually within immediate vicinity of nest site. In captive and wild birds, cack given from nest ledge or perch or in flight. In captive birds, Chitter, Whine, and Copulatory Wail typically occur at nest ledge, but in wild birds may occur as frequently on perch. In wild birds, Chitter also given in flight in a defensive context. Eechip may occur at nest ledge, perch, or cache (reproductive context), or in aerial chase. All vocalizations of young birds occur at nest ledge until about 5 wk old, when they begin to move about cliff. Female Beg may be given in air or from perch. Food/Agonistic Wails may be given at nest ledge, from perch, or in air. Advertisement Wails given from perch or in flight (NJC).
Repertoire And Delivery Of Calls
With exception of sexual differences, all individuals appear to exhibit same repertoire of calls, although there is individual variation in structure, context, and frequency. First-year breeders appear to have same repertoire as older breeders, though phenology is accelerated (Wrege and Cade 1977). Little information on vocal repertoire of adult nonbreeding birds, but with exception of cack and Wail, other vocalizations probably not used with any frequency until first year of reproduction.
Social Context And Presumed Functions
See above for associations between vocalizations and behavior. Cack is agonistic call associated with threat to territory or self. Chitter is also agonistic but appeasing more than aggressive, usually directed toward close mate, and therefore probably more closely associated with self-defense. Eechip has 2 distinct contexts: in encounters with unmated falcons near eyrie and appeasement in reproductive context. Greater frequency of eechip (reproductive context) by male suggests subordinate status relative to female (Carlier 1995). Because Beg imitates young bird, probably functions in appeasement. Copulatory Wail and Whine may also function in appeasement as they are associated with passive postures. Wail, when given by male in absence of mate, appears to function in advertisement. Wail seems to indicate bird is dissatisfied with its current state and is seeking a change (TJC).