. Bulletin of the British Ornithologists' Club. Paul J. Leader 250 Bull. 2006 126(4) 70 n 60 50 40 30 20 10 â zonorhyncha â¡ haringtoni S zonorhyncha/haringtoni . «L. Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Figure 1. Mean numbers per month of Spot-billed Ducks Anas poecilorhyncha in Deep Bay, Hong Kong in 1994 and 1997-2005 (Hong Kong Birdwatching Society data). Discussion Both zonorhyncha and poecilorhyncha breed over huge areas, largely allopatrically, but are in contact in a small area in Hong Kong, where the timings of the breeding cycle overlap exte
. Bulletin of the British Ornithologists' Club. Paul J. Leader 250 Bull. 2006 126(4) 70 n 60 50 40 30 20 10 â zonorhyncha â¡ haringtoni S zonorhyncha/haringtoni . «L. Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Figure 1. Mean numbers per month of Spot-billed Ducks Anas poecilorhyncha in Deep Bay, Hong Kong in 1994 and 1997-2005 (Hong Kong Birdwatching Society data). Discussion Both zonorhyncha and poecilorhyncha breed over huge areas, largely allopatrically, but are in contact in a small area in Hong Kong, where the timings of the breeding cycle overlap extensively, yet mixed pairs are rare. Pure pairs oi zonorhyncha and poecilorhyncha (of race haringtoni) account for 91% of pairs and mixed pairs 9%; thus zonorhyncha and haringtoni exhibit relatively high levels of assortative mating, supporting their treatment as species. The hybrid female observed in 2005 is the only record of such an individual in Hong Kong, despite careful checks of many hundreds of Spot-billed Ducks since 1993 (pers. obs.). Treatment of haringtoni as a race of poecilorhyncha and its true distribution deserve further study. In Hong Kong haringtoni appears morphologically very distinct from nominate poecilorhyncha, most notably in lacking a red bill spot even during the breeding season, but also in being more uniform overall and distinctly less spotted below. There are marked inconsistencies in the literature regarding the red bill spots in haringtoni; whilst some authors consider them to be smaller than those of poecilorhyncha (Madge & Bum 1992), others state that haringtoni lacks red bill-spots (Smythies 1986) or has at best only very faint traces of them (Baker 1927). Possibly this character in haringtoni is clinal, and that birds in the east lack bill spots; Rasmussen & Anderton (2005) stated that specimens of haringtoni from north-east India and Myanmar are very like nominate poecilorhyncha. Smythies (1986) stated ihdX poecilorhyncha has been
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