Continental rift

The azure-winged magpie (Cyanopica cyanus), has long presented a puzzle for biologists. The naturalist Alfred Wallace was one of the first to consider it. The puzzle lies in its extraordinary distribution. It exists in two distinct locations: Iberia and eastern Asia, 9,000 kilometres apart. Two alternative theories have been put forward to explain this curious distribution. The first proposes that the Iberian population was established in the sixteenth century following the introduction of birds brought back from the Far East by Portuguese sailors. The second proposes that the species had a continuous distribution across Europe and Asia north of the Himalayas before late Pleistocene glaciation isolated the two populations. However, there was no evidence for either theory until the discovery of azure-winged magpie bones from cave deposits in Gibraltar that were 44,100 years old. Unless the bones were from an unknown species, they provided compelling evidence that the magpies were long-standing residents of Iberia, supporting the second theory of glacier-induced separation of the two populations. Now a new molecular study of mitochondrial DNA from the birds has been carried out to infer their phylogeny. Samples were taken both from blood samples of living birds and from the skin of museum specimens. When they compared the sequences, the results suggested that, indeed, the populations were distinct. So it seems clear that if, conceivably, Portuguese sailors had brought the odd magpie back across the 9,000 kilometres, it would have found relatives happily at home. Disjointed: A pair of azure-winged magpies attend their nest. Their curious distribution in Iberia and eastern Asia has challenged biologists for decades to come up with an explanation. New research supports the theory that the two populations are ancient and likely to have been separated by glaciation.