BEHAVIORAL SENSITIVITY OF A DOMESTIC BIRD TO 60-HZ AC AND TO DC MAGNETIC-FIELDS

After conventional incubation (n = 2) or incubation in a 60‐Hz modulated 2450‐MHz microwave field (n = 2), four Leghorn chickens (Gallus gallus) of both genders were assessed for ability to perceive magnetic fields (dc at 4.0 milliteslas; 60‐Hz ac at 1.7 milliteslas rms) by the method of conditional suppression. Each bird operantly responded for rewards of grain while being subjected to a Pavlovian conditioning procedure in which a 90‐s presentation of an H field served as a conditional stimulus (CS) that terminated in a brief faradic shock to the feet, which served as the unconditional stimulus (US). Five to seven pairings of CS and US occurred aperiodically during daily, 60‐min sessions. A total of six tensession blocks of formal testing was conducted, two blocks with the ac field, two with the dc field, and two with a sham field in which the US alone was presented to provide control baselines of responding. Neither mode of incubation nor gender was a reliable source of variation, but highly reliable changes (Ps < 0.01) in the character of operant responding—increased variability—were observed during presentations of the ac or dc field. The domestic fowl may therefore share with several other avian species a sensitivity to H fields, although artifactual sensory cueing borne of vibration or heating of the H‐field source was not definitively ruled out. If real, the birds' sensitivity to the nominal dc field was probably associated with behavioral modulation – with incessant movement in the field by a chicken, especially of its head, during the operant‐respondent measures of conditioning. On the basis of our findings and those of other investigators, we believe that detection of H fields by avian species has its locus in the retina or in other neuroanatomical substrates of the visual system. This paper is not subject to U.S. copyright. Published in 1979 by the American Geophysical Union.