IngentaConnect Orientation of Perching Birds When the Sun Is at Low Elevation

Authors: JUSTICE M.J.¹; JUSTICE T.C.²; JOYNER K.C.²

Source: Bird Behavior, Volume 13, Number 2, 2000 , pp. 79-84(6)

Publisher: Cognizant Communication Corporation

Abstract:

A popular explanation for the dark dorsum/light ventrum color pattern seen in many avian species is crypsis through countershading. However, effective crypsis is dependent on the location of the sun in the sky and the orientation of the bird. When the sun is at low elevation, a bird would have to face its dorsum toward the sun to be countershaded. Facing its ventrum toward a low-lying sun would enhance the dorso-ventral contrast and increase conspicuousness. Thus, varying conspicuousness may be a cause of orientation behavior or a consequence of other factors affecting orientation. This study sought to determine whether some bird species orient with respect to the sun in a nonrandom fashion. To do this, the angle of perches with respect to the sun was quantified in 20 common North American bird species. Seven species faced the sun more often than expected, while the other 13 species failed to reject the null hypothesis of random orientation. These data suggest that orientation with respect to the sun is biologically significant for some avian species, but it is unclear which specific aspects of color or life history are associated with orientation toward the sun.

Keywords: Orientation Countershading Bird color Communicatio

Language: English

Document Type: Research article

Affiliations: 1: *East Carolina University, Greenville, NC 2: †Chowan College, Murfreesboro, NC

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