Fig. 5. Magnetic bearings plotted relative to magnetic north (mN) after housing in
outdoor tanks under long-wavelength light (data from
Table 1). (A) Magnetic bearings
of newts housed under long-wavelength light and tested under full-spectrum
light exhibited significant bimodal orientation (black double-headed arrow)
along a northeastsouthwest magnetic axis (38-218°, r=0.40,
P<0.02; Rayleigh test). (B) Newts housed and tested under
long-wavelength light exhibited similar bimodal orientation (26-206°,
r=0.56, P<0.001). The two distributions were not
significantly (NS) different (U2=0.087,
P>0.10; Watson U2-test). Triangles at the
edges of the two distributions show the home directions for the
south-southwest (SSW; circles, filled triangles) and east-southeast (ESE;
diamonds, open triangles) groups. Open circles and diamonds represent the
magnetic bearings of newts from which natural remanent magnetism (NRM)
measurements were later obtained (Brassart
et al., 1999).