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Java, one of the most volcanically active areas on earth, is located on the southern edge of the Sunda Shelf. To the south of the island, the Indian Ocean Plate moving north subducts below the rigid shelf and the resulting friction creates pockets of highpressure molten rock that push to the surface in the form of volcanoes (Whitten et al. 1996). The result is a series of high, isolated volcanic peaks lying west to east along the island’s spine, each isolated from its neighbours by low-lying valleys; 18 of them are over 2,000 m high (Mees 1996, Whitten et al. 1996). This geological background is fundamental to an understanding of the biogeography of Java, the island’s montane biodiversity and how to develop appropriate conservation strategies. On Java, rainfall progressively diminishes and becomes more seasonal from west to east; mountains in the west and centre regularly receive more than 6,000 mm of rain with one ‘dry’month annually, whereas those on the east of the island receive less than 1,500 mm and experience a definite dry season lasting for six months or longer (Whitten et al. 1996). Due to these environmental differences, west and east Java are classified as separate ecoregions (Olson et al. 2001, WWF 2014) with wetforest species being restricted to the west of the island, and changes in taxonomy along its length. Mees (1996) reviewed the avifaunal variation on Java at species and subspecies level. However, the distribution of taxa is still being clarified and the mechanisms and evolutionary history underlying these changes remain poorly understood. Here we describe the findings of ornithological surveys of