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ability of animals to detect and utilize directional information from the ambient magnetic field has received increasing documentation. Much of the work in this field has been focused on the navigational abilities of homing and migratory birds (Wiltschko and Wiltschko, 1988; R. Wiltschko and Wiltschko, 1995). Of the various magnetoreceptor mechanisms that(More)
In this study we investigated the effects of a pulsed radio frequency signal similar to the signal produced by global system for mobile communication telephones (900 MHz carrier, modulated at 217 Hz) on neurons of the avian brain. We found that such stimulation resulted in changes in the amount of neural activity by more than half of the brain cells. Most(More)
Electrophysiological recordings from the ophthalmic nerve and the trigeminal ganglion of the bobolink (Dolichonyx oryzivorus) indicate the presence of units (14% of the spontaneously active cells) that are sensitive to small changes in the magnetic field. The most common response was an increase in the rate of spontaneous activity. The most sensitive units(More)
Migratory Australian Silvereyes were treated with a strong magnetic pulse designed to alter the magnetization of the small magnetite particles that are found in birds' heads. Prior to the treatment, the birds preferred the northeasterly migratory direction. The pulse initially resulted in a 90° clockwise shift of orientation; however, within about a week,(More)
Extracellular recordings using glass microelectrodes were made from the ophthalmic and supraorbital nerves of a transequatorial migratory bird, the bobolink. The rate of electrical activity was modified in 15% of the spontaneously active units by earth-strength alterations of the horizontal or vertical component of the ambient magnetic field using box(More)
Behavior and electrophysiological studies have demonstrated a sensitivity to characteristics of the Geomagnetic field that can be used for navigation, both for direction finding (compass) and position finding (map). The avian magnetic compass receptor appears to be a light-dependent, wavelength-sensitive system that functions as a polarity compass (i.e., it(More)
The retinal photoreceptors of a New World migratory bird, the bobolink (Dolichonyx oryzivorus) were examined using microspectrophotometry. Based on the absorbance spectra of their visual pigments and oil droplets, retinal photoreceptors include five classes of single cones, one double cone, and one rod. The single cones contain a long-wavelength pigment(More)
The Bobolink appears to use an integrated orientation system involving at least a star compass and a magnetic compass. The magnetic compass appears to provide the primary reference for the system and the star compass serves as a secondary compass. The star compass appears to be checked against the magnetic compass every 1 to 5 nights, and adjusted to(More)