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Magnetic compass orientation is well established in night-migrating songbirds (for example reviews, see Wiltschko and

Summary: Magnetic compass orientation is well established in night-
migrating songbirds (for example reviews, see Wiltschko and
Wiltschko, 1995a, 1996), but the sensory mechanism is
unknown. Two different hypotheses have been proposed, and
both are supported by some experimental evidence. Magnetic
fields may be sensed via a quantum chemical, light-mediated,
proton pumping or free radical mechanism in the eye of the
bird (Leask, 1977; Ritz et al., 2000; Wiltschko et al., 2002)
and/or magnetic fields may be sensed via single-domain
magnetite crystals located in the nasal region (Walker et al.,
1997; Walker, 1998; Williams and Wild, 2001; Kirschvink et
al., 2001). Experimental evidence that night-migrating
songbirds seem to orient magnetically only under light of
specific wavelengths (Wiltschko and Wiltschko, 1995b) and
only if the bird's right eye is functional (Wiltschko et al., 2002)
support the mechanism involving the eye, whereas
experimental evidence that a strong magnetic pulse seems to
deter orientation for days (Wiltschko et al., 1994, 1998; Beason
et al., 1995) supports the magnetite-mediated mechanism.
Wiltschko et al. (1998) suggested that both mechanisms may


Source: Anderson, David J. - Department of Biology, Wake Forest University


Collections: Environmental Sciences and Ecology