  Recently, a putative magnetoreceptor in the upper-beak skin of homing pigeons
was chemically characterized using X-ray flourescence and absorbtion studies
[Fleissner et al., 2007. A novel concept of Fe-mineral based magnetoreception:
histological and physiochemical data from the upper beak of homing pigeons.
Naturwissenschaften 94 (8), 631-642]. In this short communication we point out
that the novel concept propagated is based on conclusions that are not
supported by data and, in fact, stand in contradiction to previously published
crystallographic and magnetic data.
