Annual Migration Density and Stopover Patterns of Northern Saw-Whet Owls (Aegolius acadicus)

The Auk ◽  
2002 ◽  
Vol 119 (4) ◽  
pp. 1154-1161
Author(s):  
David M. Whalen ◽  
Bryan D. Watts
Keyword(s):  
Aegolius Acadicus

Twenty-five year population trends in Northern Saw-whet Owl (Aegolius acadicus) in eastern North America

2021 ◽  
Vol 132 (3) ◽  
Author(s):  
Jennifer Wall ◽  
David Brinker ◽  
Scott Weidensaul ◽  
David Okines ◽  
Pascal Côté ◽  
...  
Keyword(s):  
North America ◽  
Population Trends ◽  
Eastern North America ◽  
Aegolius Acadicus

Auditory localization in the northern saw-whet owl, Aegolius acadicus

1989 ◽  
Vol 67 (8) ◽  
pp. 1955-1959 ◽  
Author(s):  
B. J. Frost ◽  
P. J. Baldwin ◽  
M. Csizy
Keyword(s):  
Great Accuracy ◽  
Auditory Localization ◽  
Head Orientation ◽  
Sound Sources ◽  
Slight Tendency ◽  
Search Coil ◽  
Aegolius Acadicus ◽  
Localization Ability ◽  
Search Coil Technique ◽  
Vertical Localization

Although there are several anecdotal reports in the literature that northern saw-whet owls (Aegolius acadicus) have extremely accurate auditory localization abilities, there have been no attempts to quantify these observations. In this study we used the search coil technique to obtain precise measurements of the northern saw-whet owl's head orientation toward either cricket chirps or mouse squeaks presented through speakers at various azimuthal positions. The results indicate owls of this species can orient their heads toward sound sources with great accuracy in the azimuthal plane, yielding mean errors of <1.0°, but show a slight tendency to undershoot more peripherally located sounds. Vertical localization is somewhat less precise, but still very accurate. Subsequent studies will be aimed at elucidating the physiological and anatomical substrates of this extreme accuracy in auditory localization ability.

Description of a species of Sarcocystis (Apicomplexa: Sarcocystidae), a parasite of the northern saw-whet owl, Aegolius acadicus, and experimental transmission to deer mice Peromyscus maniculatus

1988 ◽  
Vol 66 (10) ◽  
pp. 2118-2121 ◽  
Author(s):  
Rolando H. Espinosa ◽  
Mauritz C. Sterner ◽  
John A. Blixt ◽  
Richard J. Cawthorn
Keyword(s):  
Cyst Wall ◽  
Skeletal Muscles ◽  
Granular Layer ◽  
Peromyscus Maniculatus ◽  
Deer Mice ◽  
Thin Wall ◽  
Experimental Transmission ◽  
Aegolius Acadicus ◽  
Dose Levels ◽  
Primary Cyst

Sporocysts of Sarcocystis were recovered from the intestinal mucosa of a northern saw-whet owl (Aegolius acadicus). Sporocysts measured 12.0 × 9.7 μm (9.6–14.0 × 8.0–12.0 μm; n = 100). Doses of 0, 500, and 2500 sporocysts were administered orally to five deer mice (Peromyscus maniculatus) and five Swiss-Cox white mice (Mus musculus) At necropsy, 28 days postinoculation, deer mice administered 500 and 2500 sporocysts had sarcocysts in skeletal muscles and cardiac muscle. White mice were negative at all dose levels. Sarcocysts had a thin wall (< 1 μm) that consisted of a primary cyst wall and a coarse granular layer composed of 36.6 nm granules (25.6–51.2 nm; n = 11). Thickness of the primary cyst wall was 62.5 nm (38.4–116.1 nm; n = 10). Metrocytes were 2.3 × 1.7 μm (1.5–3.5 × 1.2–2.5 μm; n = 25). Bradyzoites were 5.2 × 1.1 μm (4–7 × 1–2 μm; n = 25).

Haemosporidian prevalence in northern saw-whet owls Aegolius acadicus is predicted by host age and average annual temperature at breeding grounds

2018 ◽  
Vol 49 (11) ◽  
pp. e01817 ◽  
Author(s):  
Monica L. Carlson ◽  
Glenn A. Proudfoot ◽  
Kaya Gentile ◽  
Janice Dispoto ◽  
Jason D. Weckstein
Keyword(s):  
Host Age ◽  
Average Annual Temperature ◽  
Breeding Grounds ◽  
Aegolius Acadicus

Delineating the origin of migratory Northern Saw-whet Owls (Aegolius acadicus) in Indiana using stable isotope analysis

10.1676/19-35 ◽  
2021 ◽  
Vol 132 (4) ◽  
Author(s):  
Landon K. Neumann ◽  
Ashley E. Higdon ◽  
Elizabeth A. Flaherty ◽  
Brad J. Bumgardner ◽  
Amy B. Wilms ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Stable Isotope Analysis ◽  
Isotope Analysis ◽  
Aegolius Acadicus

Effects of Frequency on the Directional Auditory Sensitivity of Northern Saw-Whet Owls (Aegolius acadicus)

2021 ◽  
pp. 1-11
Author(s):  
Eileanor P. LaRocco ◽  
Glenn A. Proudfoot ◽  
Megan D. Gall
Keyword(s):  
Auditory Evoked Potentials ◽  
Transfer Functions ◽  
Low Frequency ◽  
High Sensitivity ◽  
Directional Hearing ◽  
Directional Sensitivity ◽  
Low Frequencies ◽  
Aegolius Acadicus ◽  
Spatial Locations ◽  
Prey Items

Many animals use sound as a medium for detecting or locating potential prey items or predation threats. Northern saw-whet owls (<i>Aegolius acadicus</i>) are particularly interesting in this regard, as they primarily rely on sound for hunting in darkness, but are also subject to predation pressure from larger raptors. We hypothesized that these opposing tasks should favor sensitivity to low-frequency sounds arriving from many locations (potential predators) and high-frequency sounds below the animal (ground-dwelling prey items). Furthermore, based on the morphology of the saw-whet owl skull and the head-related transfer functions of related species, we expected that the magnitude of changes in sensitivity across spatial locations would be greater for higher frequencies than low frequencies (i.e., more “directional” at high frequencies). We used auditory-evoked potentials to investigate the frequency-specific directional sensitivity of Northern saw-whet owls to acoustic signals. We found some support for our hypothesis, with smaller-magnitude changes in sensitivity across spatial locations at lower frequencies and larger-magnitude changes at higher frequencies. In general, owls were most sensitive to sounds originating in front of and above their heads, but at 8 kHz there was also an area of high sensitivity below the animals. Our results suggest that the directional hearing of saw-whet owls should allow for both predator and prey detection.

Frequency sensitivity in Northern saw-whet owls (Aegolius acadicus)

2017 ◽  
Vol 204 (2) ◽  
pp. 145-154 ◽  
Author(s):  
Julia R. Beatini ◽  
Glenn A. Proudfoot ◽  
Megan D. Gall
Keyword(s):  
Frequency Sensitivity ◽  
Aegolius Acadicus
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