Habitat use and population dynamics of the Azure-Winged Magpie ...

The extreme disjunct distribution of C. cyanus has attracted interest since the mid-19 th century
(Wallace, 1881 in Fok et al., 2002) and two alternative theories have been put forward to explain
this disjunct distribution. The first, the ‘introduction theory’ proposes that the Iberian population
was established in the 16 th century by Portuguese sailors who brought them back from the far east
(Dos Santos, 1968, Tyrberg, 1998 in Fok et al., 2002). Alternatively, the ‘refugium theory’
proposes that the species had a more continuous range prior to the Pleistocene glaciations. The
advance of the ice (Goodwin 1986, in Fok et al. 2002) caused isolation and divergence between
the birds in these two regions (but see Klicka & Zink, 1997; Avise & Walker, 1998). The fairly
marked racial difference of the Iberian race from the Asian races suggests that they have been
isolated in Europe for a long time, and not introduced recently (Madge & Burn, 1994). However,
there was no conclusive evidence to support either theory, until the discovery of C. cyanus bones
from late Pleistocene sites in Gibraltar that were at least 44,100 years old, which is not consistent
with the ‘introduction theory’ (Cooper, 2000). Even if there was a chance of mistaken identity of
the bones, recent studies show that the European race diverged from the Asian races 1.2 million
years ago, which also disproves the ‘introduction theory’, and this renders them distinct enough
to be classified as different species (Fok et al., 2002). However, within the Asian clades, both
genetic and morphological differences between putative subspecies were not distinct enough for
them to be regarded as such (Fok et al., 2002; Kryukov et al., 2004). As a result of their studies,
Fok et al. (2002) have suggested that the Iberian subspecies be recognised as a separate species,
Cyanopica cooki (Bonaparte, 1850) and the Asian birds continue to be named Cyanopica cyana 2
(Pallas, 1776). For the sake of simplicity, I will retain the use of Cyanopica cyanus as a general
name for this species. When needed, I will refer to regions when mentioning different
populations.
(a)
9, 10
2
See Dickinson Dickinson, E.C., (Editor) (2003) The Howard & Moore Complete Checklist of the Birds of the
World, 3rd edn. Christopher Helm, London. for changes to species name.
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