منابع مشابه
Vernier acuity in barn owls
Vernier acuity thresholds were obtained psychophysically in three adult barn owls with vertical bars and sinusoidal gratings. A minimal displacement threshold of 0.58 arcmin was observed with the bar stimulus under binocular viewing conditions. The mean binocular bar threshold was 2.51 arcmin. Bar thresholds were lower than grating thresholds. Monocular thresholds, obtained in one bird only, we...
متن کاملGloger’s rule in North American Barn Owls
Studying the geographic variation of phenotypic traits can provide key information about the potential adaptive function of alternative phenotypes. Gloger’s rule posits that animals should be darkvs. light-colored in warm and humid vs. cold and dry habitats, respectively. The rule is based on the assumption that melanin pigments and/or dark coloration confer selective advantages in warm and hum...
متن کاملAcoustic Location of Prey by Barn Owls
The external ears of many species of owls are asymmetrical (Ridgeway, 1914; Stellbogen, 1930). Although the asymmetry may involve the modification of different structures in different species (Stellbogen, 1930) the result is usually the same: one ear has its opening above the horizontal plane, the other below it. Though Pumphrey (1948), Southern (1955) and others have suggested that the asymmet...
متن کاملFood-niche Relationships Between Great Horned Owls and Common Barn-Owls in Eastern Washington
organs. There are only two serious limitations to using feather pulp for electrophoretic analysis. First, the birds must either be molting when sampled or be subjected to plucking to stimulate feather regrowth and then recaptured at a later date. Second, in small birds such as Bobolinks, warblers (Parulidae), or chickadees (Parus spp.), only tiny amounts of tissue can be obtained from the fligh...
متن کاملA Dominance Hierarchy of Auditory Spatial Cues in Barn Owls
BACKGROUND Barn owls integrate spatial information across frequency channels to localize sounds in space. METHODOLOGY/PRINCIPAL FINDINGS We presented barn owls with synchronous sounds that contained different bands of frequencies (3-5 kHz and 7-9 kHz) from different locations in space. When the owls were confronted with the conflicting localization cues from two synchronous sounds of equal le...
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ژورنال
عنوان ژورنال: Science
سال: 1884
ISSN: 0036-8075,1095-9203
DOI: 10.1126/science.ns-3.52.116