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Food Call of young is a wheezy hiss, or hisslike peep (Cramp 1985a); shrill, high-pitched hiss-khweeee, similar to food call of Broad-winged Hawk (Buteo platypterus), but rising at the end (Torres 1990); soft screeching, also faint version of screeeee-yip call (see below) when young were approached while in the nest (Smith 1970a). Angry fledglings give brittle cackle, hiss loudly, and snap bills (Eckert 1974). Ksssssss'itt call (1.5 s) given throughout the day; heard at 200-340 m (Cramp 1985a). Hoarse crescendo pssssssssssitt, with itt ' higher pitched and i drawn out; similar calls given by older young in flight when mobbed by passerines (Cramp 1985a), and by recently fledged owl at approaching intruder, resemble weaker adult Screeching Call (see below; Smith 1970a, Leinonen 1978).
Kssakssakssa or tchapptchapp calls given by very excited young; similar to Yelping Call (see below) of adult (Cramp 1985a). Hup hup call given by satiated young when refusing food from female (Cramp 1985a). When adult nearby, small fledgling gave rapid set of loud sharp cheeps, while larger fledgling gave ascending rapping calls, similar to adult female's Screeching Call (Wilson 1993b).
No data on differences, if any, between vocalizations of S. u. caparoch (North America) and those of S. u. ulula (Europe and Asia). Versatile and persistent vocalist during breeding; less so during winter.
Advertising Call. Display call of male. A trilling, rolling whistle, ulululululululul, lasting up to 14 s (Mikkola 1983). Described by Henderson (Henderson 1919) and Eckert (Eckert 1974) as tu-wita-wit, tiwita-tu-wita, wita, wita ... Given at 2-s intervals, especially during Display Flight (see Behavior: locomotion, below; Cramp 1985a); also used when perched to draw female's attention to a potential nest site (Glutz Von Blotzheim and Bauer 1980) and later to summon an incubating female (Leinonen 1978). Weak call heard at 500 m in calm weather (Mikkola 1983). More gentle call, whut-tu-tu-ooo-ooo-ooo, given late in the day (Eckert 1974). Female Advertising Call is less constant in rhythm and pitch; hoarser, shriller, and shorter (Glutz Von Blotzheim and Bauer 1980, Cramp 1985a). S. Wilson (pers. comm.) reported each phrase being vocalized every 15 s to 2 min, and lasting 7-9 s. Can last up to 30 s (Todd 1963a).
Alarm Call, or Screeching Call. Used by both sexes. Described by Henderson (Henderson 1919) as rike, rike, rike, rike, and occasional whir-u, whir-u, whir-u while flying. Rapid series of similar syllables- kee-kee-kee-kee or kip-kip-kip-kip -usually in flight (Smith 1970a). Uses raspy, 2-part screech, screeeeee-yip, with emphasis on last syllable; usually given when intruder is near nest (Smith 1970a, Mikkola 1983, Lane and Duncan 1987). Calls vary in length from 0.5 to 1.45 s (Lang et al. 1991). Given by male and female at sight of rivals (Glutz Von Blotzheim and Bauer 1980) and as contact call when male brings prey to the nest, or when female is calling to young (more often when young leave nest; Ritchie 1980a, Mikkola 1983). Repeated, drawn out (1.2-1.3 s) wheezy aaaaa-ik, emphasis on ik, when intruder at nest with older young. A furious tschi-itsch by female between attacks, while bobbing head and tail (Cramp 1985a).
Trilling Call. A sharp trill kiiiiiiiirrl when an intruder is at the nest (Cramp 1985a). Male call is a soft, purring, rolling sound; female call is a loud, shrill, metallic sound (Glutz Von Blotzheim and Bauer 1980). Pllllllrritl call by both sexes is heard at nest during disturbance (Cramp 1985a); also used as contact call during pair formation, nest-site inspection, billing, summoning mate, as a duet when passing prey, or during copulation (Glutz Von Blotzheim and Bauer 1980). Clear, descending whinnying sound given by bird flying excitedly in fall and winter, may serve as long-distance contact (Glutz Von Blotzheim and Bauer 1980). May be used during breeding; female gives hoarse, drawn-out kshee-lip, possibly when soliciting food, in response to her mate. Penetrating shrill schpeep, ending in tremolo; function unclear.
Yelping Call. Sharp kwitt kwitt, kwi kwi, ki ki ki, or ki ki kikikikiki; used as warning by both sexes near threatened nest or fledged young; male call is higher-pitched (Leinonen 1978, Glutz Von Blotzheim and Bauer 1980). Also described as kvitt kvitt, 2/s (Cramp 1985a). Described as ki-ki-ki by Lang et al. (Lang et al. 1991), given individually or in a group, with individual calls about 0.2 s apart. Given in flight during aerial attack or when perched with tail pumping (Cramp 1985a).
Lure Call. Shrill, hard sound, used during nest inspection and gaping, especially by female, or by male before female enters prospective nest site (Glutz Von Blotzheim and Bauer 1980).
Soliciting Call. Hoarse chat or chut, usually ending in a loud squeak. Used by female, accompanied by wide circular motion of head, when inviting copulation (Glutz Von Blotzheim and Bauer 1980).
Chitter. S. Wilson (pers. comm.) described a paired female giving soft chirps and chitters while preening.
Other Calls. Female uses a srii-srii when feigning injury (Mikkola 1983). Hunting Call described by Smith (Smith 1970a) as queep-queep-queep, cheep-cheep-cheep, or squee-squee-squee; uttered when alert adult on treetop is looking around. He interprets Godfrey's (Godfrey 1986) description, kleep-kleep, also as a Hunting Call. Peeping or squeaking call given by a hunting hawk owl during winter when approached closely (S. Crocoll pers. comm.). Female gives kuk kuk when bringing food to the nest; male gives the same call when an intruder approaches the nest (Leinonen 1978).
Soft quiet calls by females described as follows: gjuhk rarely heard (Glutz Von Blotzheim and Bauer 1980); mui in answer to male Advertising Call, possibly same as cuee or sreee sreee given at the nest when young also giving Food Calls; perhaps invites close approach and is similar to Lure Call (Leinonen 1978); soft slightly ascending chatter-toot (about 1 s) while in cavity; male heard giving loud Northern Flicker-like (Colaptes auratus) call before leaving and when entering breeding territory (Wilson 1993b). Gives kr-r-r-r-r or krrrrouk with varying inflections-from throaty call to penetrating scream; also a hoarse, quivering moan by the female (Todd 1963a).
Confines most vocal efforts to the breeding period (Guiguet 1978b). Male on winter territory in s. Manitoba was first heard calling 5 Mar; 10 Feb in n. Minnesota (Lane and Duncan 1987, Nero 1995), elsewhere in North America, Feb-Apr (Bent 1938b). Males heard giving Advertising Call both in early morning and in evening (Lane and Duncan 1987, Nero 1995).
See above; needs study. Male Advertising Call given from top of prominent perches in territory; calling every 2-5 min for 15-min period (Nero 1995).
Adults and young snap bill when threatened (Norman 1921).