Data from: Dramatic niche shifts and morphological change in two insular bird species

Colonizations of islands are often associated with rapid morphological
divergence. We present two previously unrecognized cases of dramatic
morphological change and niche shifts in connection with colonization of
tropical forest-covered islands. These evolutionary changes have concealed
the fact that the passerine birds madanga, Madanga ruficollis, from Buru,
Indonesia, and São Tomé shorttail, Amaurocichla bocagii, from São Tomé,
Gulf of Guinea, are forest-adapted members of the family Motacillidae
(pipits and wagtails). We show that Madanga has diverged mainly in
plumage, which may be the result of selection for improved camouflage in
its new arboreal niche, while selection pressures for other morphological
changes have probably been weak owing to preadaptations for the novel
niche. By contrast, we suggest that Amaurocichla's niche change has
led to divergence in both structure and plumage.