Interaction of magnetite-based receptors in the beak with the visual system underlying 'fixed direction' responses in birds

Table 1 Orientation of binocular and monocular robins: compass orientation and a 'fixed direction' response

Response	Light (nm)	Eyes	N	med r_b	α_N	r_N	Δbi
Compass orientation	502	binocular	12	0.96	21°	0.62**
	502	monocularly right-eyed	12	0.74 ^n.s.	11°	0.97***	-10° *
	502	monocularly left-eyed	12	0.39 **	265°	0.04^n.s.	-116° **
'fixed direction'	502 + 590	binocular	12	0.49	94°	0.64**
	502 + 590	monocularly right-eyed	12	0.84^n.s.	78°	0.81***	-16° ^n.s.
	502 + 590	monocularly left-eyed	12	0.65 ^n.s.	66°	0.67**	-28° ^n.s.

The column Light gives the wavelength of light; N, number of birds tested, med. r_b, median of the vector lengths based on the three recordings per bird, with asterisks indicating significant differences by the Mann Whitney U-test to the binocular tests under the same light; α_N, r_N, direction and length of the grand mean vector, with asterisks at r_N indicating significance by the Rayleigh Test [17]. The last two columns give the angular differences to the binocular tests under the same light conditions and indicate significant differences in variance by the Mann Whitney U-test. Significance levels: ***, p < 0.001; **, p < 0.01; *, p < 0.05; n.s., not significant.

ISSN: 1742-9994