Orientation of migratory birds under ultraviolet light
- 608 Downloads
In view of the finding that cryptochrome 1a, the putative receptor molecule for the avian magnetic compass, is restricted to the ultraviolet single cones in European Robins, we studied the orientation behaviour of robins and Australian Silvereyes under monochromatic ultraviolet (UV) light. At low intensity UV light of 0.3 mW/m2, birds showed normal migratory orientation by their inclination compass, with the directional information originating in radical pair processes in the eye. At 2.8 mW/m2, robins showed an axial preference in the east–west axis, whereas silvereyes preferred an easterly direction. At 5.7 mW/m2, robins changed direction to a north–south axis. When UV light was combined with yellow light, robins showed easterly ‘fixed direction’ responses, which changed to disorientation when their upper beak was locally anaesthetised with xylocaine, indicating that they were controlled by the magnetite-based receptors in the beak. Orientation under UV light thus appears to be similar to that observed under blue, turquoise and green light, albeit the UV responses occur at lower light levels, probably because of the greater light sensitivity of the UV cones. The orientation under UV light and green light suggests that at least at the level of the retina, magnetoreception and vision are largely independent of each other.
KeywordsMagnetoreception UV cones Monochromatic light Migratory orientation ‘Fixed direction’ responses
Our work was supported by the Deutsche Forschungsgemeinschaft (grants to WW and RW). We sincerely thank H.J. Bischof, Universität Bielefeld, and L. Peichl, Max-Planck-Institute for Brain Research, Frankfurt am Main, for valuable discussions and comments, F. Geiser, University of New England, Armidale, for his logistic help and all students who participated in conducting the experiments, in particular S. Denzau and D. Gehring.
The animal care and the performance of the experiments were in agreements with the laws, rules and regulations for animal welfare in Australia and Germany.
- Batschelet E (1981) Circular statistics in biology. Academic Press, LondonGoogle Scholar
- Falkenberg G, Fleissner G, Schuchardt K, Kuehbacher M, Thalau P, Mouritsen H, Heyers D, Wellenreuther G, Fleissner G (2010) Avian magnetoreception: elaborate iron mineral containing dendrites in the upper beak seem to be a common feature of birds. PLoS One 5:e9231PubMedCentralPubMedCrossRefGoogle Scholar
- Goldsmith TH, Butler BK (2003) The roles of the receptor noise and cone oil droplets in the photopic spectral sensitivity of the budgerigar, Melopsittacus undulatus. J Comp Physiol A 189:135–142Google Scholar
- Hunt DM, Peichl L (2013) S cones: evolution, retinal distribution, development, and spectral sensitivity. Vis Neurosci (in press). (http://dx.doi.org/10.1017/S0952523813000242)
- Ritz T (2001) Disrupting magnetic compass orientation with a radio frequency oscillating field. In: Orientation and navigation—birds, humans and other animals. Royal Institute of Navigation, Oxford, paper 4Google Scholar
- Wiltschko R, Ritz T, Stapput K, Thalau P, Wiltschko W (2005) Two different light-dependent responses to magnetic fields in birds. Curr Biol 16:1516–1523Google Scholar