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Thread: RFI - Northern Saw-whet Owl vocals

  1. #1
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    Oct 2008
    Eastern USA

    Default RFI - Northern Saw-whet Owl vocals

    Greetings all,

    Can anyone out there reference a good and complete set of written vocal transcriptions for Northern Saw-whet Owl? Or perhaps direct me to a good set of sound recordings on line?

    Most commercial (and on-line) sound recordings focus on the territorial monotonous whistled 'toot', and a few variations on this, and at least one contains a more explosive screech 'shrreeee' type call. These are also the calls described in most NA field guides. Sibley also describes a softer 'keew' or 'pew' which is one of the call types that hear most frequently in my area (Western Massachusetts).

    I read, however, that at least 9 vocalizations have been described for this owl and wondered how to find out more about these? For a popular, and apparently quite common, small owl I'm having a tough time finding a broader range of voice descriptions than those described above.

    Thanks in advance for any help you can offer.

    Best Wishes,

    James P. Smith
    Amherst, MA.

  2. #2
    Senior Member Alex Lees's Avatar
    Join Date
    Jan 2008


    Quote Originally Posted by James P. Smith View Post
    Greetings all,

    Can anyone out there reference a good and complete set of written vocal transcriptions for Northern Saw-whet Owl? Or perhaps direct me to a good set of sound recordings on line?
    see below:

    Vocal Array
    At least 11 different vocalizations reported, 4 are illustrated in Fig. 3. The common vocalizations seem homologous to those of the Boreal Owl described by Bondrup-Neilsen (1984). There is little consensus as to which is the “saw-whet” call from which the species is named; nomination include numbers 1, 3, and 4 below. Individual variation in the calls of Saw-whet Owls has been observed (Otter 1996, Holschuh 2004). Hill (1995) recorded calls uttered by one bird that did not resemble published descriptions.

    Advertising call: A monotonous series of whistled notes on a constant pitch. Can be heard up to 300 m away through forest and up to 1 km away over water (Swengel and Swengel 1987, Milling et al. 1997). Series generally begins with a relatively short upsweep in frequency to a relatively long and constant frequency that is followed by a brief drop in frequency at the end of the bout (Hill 1995). Whistled notes of acadicus are given on a constant pitch of about 1,100 Hz (Mean 1,104.7, SD 59.5, n = 10, 1,030-1,205) at a rate of about 2/s (Fig. 3a). In Massachusetts, Tennessee, and North Carolina, Hill (1995) found that the notes of the advertising call were given at a mean frequency of 1,133 Hz ( 95 SD) and a rate of 117.7 calls/min ( 30.2 SD) and had a duration of 0.125 s ( 0.020 SD) with an inter-note interval of 0.42 s ( 0.14 SD) (n = 7 individuals, 280 calls).

    Advertising call given almost entirely by males, but females produce a version during courtship. Barb (1995) observed a female giving the advertising call from inside a nest box on 19 April 1994 at 7:45 EST. Female version of advertisement call similar to that of male but softer and less consistent in pitch and amplitude (K. McKeever pers. comm., Cannings 1993).

    Frequency of the advertisement call notes varies significantly and explains most variation among males (F4,41 = 8.04, P < 0.001; R2 = 0.93). This allows accurate identification of individuals using sonographic analysis of recordings (in addition to location of the calling owl; Otter 1996). Individuality of the advertisement call was maintained between nights with 86.4% of the variation attributable to between individuals and 2.8% between nights (Otter 1996).

    The whistled notes of the male advertisement call of brooksi were 0.113 s ( 0.01 SD, n = 26) given at a frequency of 1194 Hz ( 47.2 SD, n = 26) and a rate of 2 or 3 /s (Holschuh 2004). Notes of the female and male advertisement call of brooksi are similar except that the females’ are given at higher and less constant frequencies and have been described as having a more ‘barky’ quality (Holschuh 2004). The variance in the advertisement calls among males allows for the correct ascription of identity to individuals 74% of the time when multiple recordings were analyzed (Holschuh 2004).

    Changes in call rate of individual males from night to night were positively correlated with changes in temperature (R = 0.555, n = 13, P = 0.049), perhaps related to changes in male condition (Holschuh 2004).

    Call rate has been positively correlated with the amount of mature/old forest near the core of a territory (Michaelis-Menten relationship, R = 153.9, 2 df, n = 26, p < 0.0001; Holschuh 2004). With one outlier removed, 41.1% of the variation in call rate was explained by the amount of old growth forest within 500 m of the middle of the territory (n = 25, r = 0.641; Holschuh 2004).

    Function of this call seems to be territorial: often heard in response to playback of the same call, with males often replying with a softer and lower pitched version given faster (4 to 5 notes/s; Cannings 1993). The advertising call has also been referred to as the toot call (Hill 1995) and the too-too-too call (Swengel and Swengel 1987).

    Rapid call: A softer, lower pitched, and more rapid (i.e., 4-5 notes/s) version of the male advertisement call, similar to the male response to advertising call described above (Cannings 1993, Holschuh 2004). Used in multiple contexts: (1) as contact call given by males approaching the nest with food, to which female usually replies with a Tssst call followed by the transfer of food to female at the entrance of the nesting cavity (described as the “visiting call” by Johns et al. 1978, Cannings 1993, Holschuh 2004); (2) as pre-copulatory duet call given by males (not followed by the male advertising song), to which females reply with the Tssst call (Holschuh 2004) and; (3) an introductory component of the advertisement call (Otter 1996).

    Whine: Described as ho...., call is 0.9 s with harmonics and has an upward sweeping quality in pitch (starting at 1,050 Hz and ending at 1,300 Hz) and volume (Cannings 1993, Holschuh 2004; see Fig. 3b). Males utter call repeatedly for 2 to 3 min at approximately 1 call every 3 s in response to playback. Males utter this call in highly agitated contexts (Holschuh 2004). Slight variations are heard in eastern populations: duration of 1.139 s ( 0.52 SD), intercall interval of 6.61 s ( 10.25 SD), a frequency of 1,133 Hz ( 163 SD), given at a rate of 21.3 calls/min ( 18.0 SD), increase in frequency for the first 2/3 of call and a decrease in frequency for the last 1/3 of the call (n = 23 individuals, 23 calls; Hill 1995). The whine has also been referred to as a “meow or high-pitched meow” (Holschuh 2004) and a “gasping and decidedly uncanny ah-h-h” or “rasping, querulous sa-a-a-ay” by (Bent 1938).

    Ksew call: Highly variable, rapidly repeated in single or multiple bouts (mean calls/bout: ± S.D. = 4.7 3.3; n = 20 bouts, 20 individuals; 11 of 20 owls gave three or fewer) of short, high-frequency notes with harmonic overtones (Hill 1995). Described as a harsh and startlingly loud staccato high-pitched bark (Hill 1995), duration of 0.095 s ( 0.044 SD), note duration of 0.073 ( 0.058 SD), internote interval of 0.055 ( 0.096 SD), frequency of 2652 Hz ( 1871 SD), and uttered at 1.5 notes/min (n = 20 individuals, 20 calls). Calls start at 1300 Hz, decrease to 1000 Hz and are 0.1 s long in brooksi (Holschuh 2004). Brewster (in Bent 1938) describes this call as resembling “…the sounds produced by filing a large mill saw...”. Holschuh (2004) suggests this call is given when an owl is agitated by an intruder (or playback).

    Saw-whet Owls in Colorado responded to playback of the Boreal Owl’s primary song with a call that resembled Boreal Owl’s skiew call, which is most likely the Saw-whet Owl’s described ksew call (Palmer and Rawinski 1986).

    Tssst call: A distinctive high-frequency call usually composed of two harmonically unrelated whistles that differ in frequency by 100-1000 Hz uttered in bouts and at a rate of 1 call every 4-5 s (Hill 1995; see Fig. 3c). Given only by females in pre-copulatory dueting with males performing the rapid call and when males deliver food to the nest (Cannings 1993, Holschuh 2004). The Tssst call of brooksi females has a frequency of 9,500 Hz, is 0.3 s, repeated every 1-2 s (Holschuh 2004). Tssst call of acadicus females is 0.203 s ( 0.039 SD) with a frequency of 8,511 Hz ( 392 SD) (n = 9 individuals, 161 calls). The Tssst call has also been referred to as the “seet” call by Hill (1995). The “soft swee notes with rising inflection” described by Johnsgard (1988) possibly refer to this call.

    Chirruping begging call of nestlings: Call given by nestlings consisting of 6 to 8 elements with a dominant frequency of about 2500 Hz. They last about 0.75 seconds and are given at a rate of 1/s. Gradually change to the co....r tssshk begging calls given at and after fledging.

    Squeaks: Short calls with harmonic qualities described as an insect-like buzz by Collins (1993). In brooksi, this call has a two-note component given over 0.3 s; the first note is higher than the second (Holschuh 2004). May function as a threat display as uttered at very close range while flying by or attacking an intruder (Collins 1993, Holschuh 2004).

    Twittering call: The highly variable multi-note twittering call has also been described as “chitters” by Hill (1995) and has a duration of 0.656 s ( 0.409 SD; range = 0.220 to 1.344 s with unrecorded calls sometimes > 2 s), note duration of 0.016 s ( 0.009 SD), internote interval of 0.010 s ( 0.008 SD), and frequency of 5309 Hz ( 1367 SD) (n = 7 individuals, 7 calls). Usually one twittering call given per individual, but as many as four given sequentially by a single owl (Hill 1995). Number of notes range from 4 to 25 (Hill 1995), similar to American Woodcock (Scolopax minor; Brigham 1992).

    Guttural chuck: Captured birds often give a single, short, relatively guttural “chuck” call immediately upon release (D. Evans pers. comm. in Cannings 1993).

    Transition call: As of yet, this call has been recorded only in brooksi (Holschuh 2004). Notes increase in duration (i.e., from 0.17 s through a calling bought) and frequency (i.e., from 1200 Hz to 1500 Hz through the duration of each note) and are repeated at a rate of 1 to 2 note/s (Holschuh 2004). Is uttered by highly agitated males between calling bout and series of whines (Holschuh 2004).

    Alternate whine: As of yet, this call has only been recorded in brooksi: 1500 Hz, 0.4 s duration, and is often repeated for several minutes (Holschuh 2004). Used by agitated males at the end of an advertisement calling bout; sometimes used by males in response to playback (Holschuh 2004).

    Males give advertising calls from late Jan through May (in s. British Columbia, peak in late Feb and Mar, Cannings 1993; in Wisconsin, 10 Feb to 27 Apr, Swengel and Swengel 1987; Colorado peak in Apr, Palmer 1987). Tapering off in May (w. Wyoming, 70% of the vocalizations occur between 1 Mar and 15 Apr, Clark and Anderson 1997; in central Sierra Nevada, Mar and Apr, Crozier et al. 2003; on Santa Cruz I., CA, between 6 Mar and 7 Apr, Johnson 1999; Manitoba April and early May, Manitoba Avian Record Committee 2003). Some males (usually unmated) sing into May or even Jun in British Columbia, and there seems to be a minor resumption of singing in Aug and Sep (Cannings 1993). Songs heard throughout winter (Nov to Apr) on the Channel Is., CA (C. Collins pers. comm. in Cannings 1993). Increased day length may stimulate the onset of singing, as it does in the Boreal Owl (Palmer 1987). One nesting male sang for a period of 93 d (Palmer 1987).

    High wind speeds and precipitation inhibit song production (Palmer 1987). Owl response rates lower on nights with wind speeds above Beaufort 2 than nights with wind speeds of Beaufort 0-2 (Stedman 2001). Findings concerning the effect of the phase of the moon on calling are mixed. Palmer (1987) suggests that a full moon may stimulate the seasonal onset of calling. Similarly, Clark and Anderson (1997) heard more vocalizations during the waxing of the full moon phase, but Stedman (2001) found that variations in the phase of the moon did not affect calling rates. Effect of temperature on calling rates also mixed, with no affect in Big South Fork National River and Recreational Area, TN and KS (Stedman 2001), whereas Saw-whets vocalized less than expected when temperatures dropped below -5°C in Wyoming (Clark and Anderson 1997). Singing has been heard at temperatures as low as –30°C (Crozier et al. 2003). Clark and Anderson (1997) found that Saw-whet Owls were more vocal when cloud cover was between 50 and 75%. Palmer (1987) suggests that, as in Boreal Owls, Saw-whet Owls call more frequently in years of higher prey abundance because they are more likely to raise young.

    Owl populations may be more stable than auditory censuses suggest because more owls are known to be present than are calling in some years, based on pellet, roost, and roosting owl searches (Palmer 1987, Swengel and Swengel 1995). Instead, the periodicity in the calling behavior may be related to the local abundance of mammalian prey (Swengel and Swengel 1995).

    Daily Pattern Of Vocalizing

    Sing from within a half hour after sunset until sunrise. Calling peaks at 2 h after sunset and decreases until just before sunrise (Clark and Anderson 1997). Daily pattern of vocalizing does not change throughout the season (Clark and Anderson 1997). Short bursts of the advertising song are often emitted in midday in response to playback (Cannings 1993).

    Places of vocalizing. Advertising song usually given from high but concealed perches, e.g. from within the crown of a tree, occasionally males sing from prospective nest-hole. Contact calls and songs produced in response to playback of song are usually given from dense cover, e.g. less than 1 m up in shrubbery.

    Nonvocal Sounds
    Bill snap apparently an alarm call, most often heard when a bird is captured or approached closely. Nestlings snap bills when handled after eyes open between 7 and 10 d of age.

    Rasmussen, Justin Lee, Spencer G. Sealy and Richard J. Cannings. 2008. Northern Saw-whet Owl (Aegolius acadicus), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online:

    Dept. of Zoology, University of Cambridge, UK

    My website - Neotropical Bird Club -Tropical Forest Research - Punkbirder - Wikiaves

    In natural science the principles of truth ought to be confirmed by observation. — Carolus Linnaeus

  3. #3
    Junior Member
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    Oct 2008
    Eastern USA



    Brilliant! This is exactly what I was hoping to find. Thanks very much indeed.


    James P. Smith
    Amherst, MA.

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