Barn owls display larger black feather spots in cooler regions of the British Isles
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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...
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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...
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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...
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ژورنال
عنوان ژورنال: Biological Journal of the Linnean Society
سال: 2016
ISSN: 0024-4066
DOI: 10.1111/bij.12814