R. Sandberg et J. Pettersson, MAGNETIC ORIENTATION OF SNOW BUNTINGS (PLECTROPHENAX-NIVALIS), A SPECIES BREEDING IN THE HIGH ARCTIC - PASSAGE MIGRATION THROUGH TEMPERATE-ZONE AREAS, Journal of Experimental Biology, 199(9), 1996, pp. 1899-1905
Orientation tests were conducted with snow buntings (Plectrophenax niv
alis) exposed to artificially manipulated magnetic fields, during both
spring and autumn migration. Experiments were run under clear sunset
skies and under simulated complete overcast. The birds closely followe
d experimental shifts of the magnetic fields during both seasons regar
dless of whether they had access to celestial cues. Clear-sky tests in
vertical magnetic fields resulted in a significant bimodal orientatio
n, the directionality of which was almost identical during spring and
autumn. When the snow buntings were deprived of celestial directional
information and tested in vertical magnetic fields, they failed to sho
w any statistically significant mean directions in either spring or au
tumn. The results demonstrate that snow buntings possess a magnetic co
mpass and suggest that magnetic cues are of primary importance for the
ir migratory orientation while on passage through temperate-zone areas
. However, the axial orientation in vertical magnetic fields under cle
ar skies may indicate an involvement of celestial cues as an auxiliary
source of directional information.