The Woodswallows are gathered in one genus, Artamus. They have an Australasian distribution, with most species occurring in Australia and New Guinea.
Two species interbreed, the White-browed Woodswallow (A. superciliosus) and Masked Woodswallow (A. personatus) (Barnard, 1944; Boehm, 1974; McGill, 1944). Molecular analyses (mtDNA) showed that these species are polyphyletic, which can be explained by introgressive hybridization (Joseph et al., 2006).
The Black-faced Woodswallow (A. cinereus) can be divided into two subspecies, based on the colour of the vent and under-tail coverts, namely white (albiventris) or black (melanops). Hybridization between these subspecies was assessed using a hybrid index (Ford, 1978).
Barnard, H. (1944). Hybrid wood-swallows. Emu 44, 154-154.
Boehm, E. (1974). Hybridism in wood-swallows. S. Aust. Orn 26, 167.
Ford, J. (1978). Hybridization between the White-Vented and Black-Vented forms of the Black-faced Woodswallow. Emu 78, 105-114.
Joseph, L., Wilke, T., Ten Have, J. & Chesser, R. T. (2006). Implications of mitochondrial DNA polyphyly in two ecologically undifferentiated but morphologically distinct migratory birds, the masked and white-browed woodswallows Artamus spp. of inland Australia. Journal of Avian Biology 37, 625-636.
McGill, A. (1944). Hybridism in Wood-swallows. Emu 44, 153-154.