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Vertebrates
Is the Javan Mongoose native and does it matter?
by Richard T. Corlett
Kylie Chung's capture of three Javan Mongooses (Herpestes javanicus) in grassland on Tai Mo Shan (see Wild Corner) is the latest example of a dramatic expansion in the range and abundance of this species in Hong Kong over the last decade. It now seems to be common in the northwest New Territories, with scattered records from the centre and the northeast. The first definite record for Hong Kong was one caught in a rat trap at Mai Po in 1989, but David Dudgeon thinks he saw one at Plover Cove in the early 1980s. All pre-1980 mongoose records refer to the larger, water-associated, Crab-eating Mongoose, H. urva. The Javan (or Small Asian, or Small Indian) Mongoose has a huge native range, from Iraq and Iran in the west, to Java in the south, and Guangdong in the east. It has also been widely introduced outside its range for the control of rats, in some cases with disastrous consequences for native wildlife.
Hong Kong is near the eastern margin of the recent range of this species, and it is possible that it was simply overlooked, or confused with the Crab-eating Mongoose, prior to the 1980s. However, it is a pretty distinctive animal and one that would have been well-known to many of the early naturalists in Hong Kong. It seems more likely that it is a recent, deliberate introduction. Mongooses are widely seen as "good animals", which can control "bad" ones, such as rats and snakes, so deliberate releases are common. Even if it is a recent introduction, it is possible that it was present here in the past and was then extirpated, i.e. it is a RE-introduction. This also I think unlikely. Although it appears to be a habitat generalist, there is some suggestion in the literature of a preference for non-forest habitats, both in its native range and where introduced. It is also widely reported as a commensal species, living around villages and in urban areas throughout its Asian range. This is not the ecology of a species that is particularly vulnerable to human-caused habitat changes. On balance – and this is untestable unless earlier records can be found – I think it likely that the Javan Mongoose in Hong Kong is a recent introduction outside its natural range. Indeed, its current range in southern China may well have been expanded by deliberate introductions.
Curiously, the ecology of the Javan Mongoose as an introduced species is far better known than its ecology within its native range. All studies, however, agree that it is an opportunistic, omnivorous carnivore, feeding principally on rodents, birds (and their eggs) and insects, although fruit dominates the winter diet of an introduced population in the Adriatic. It forages during the day, except in close contact with humans, when it may become nocturnal. It can climb trees but is usually observed on the ground.
Mongoose introductions have been disasters on islands lacking native carnivores, but Hong Kong supported at least nine other mammalian carnivores a century ago. It thus seems unlikely that one more is going to have much additional impact. Our ignorance, though, is worrying. For a start, we know virtually nothing about its diet in Hong Kong. Kylie's traps were baited with deep-fried batter, the one David saw was inspecting a rubbish bin, and Michael Lau has seen it feeding on dead fish at Mai Po. Clearly they scavenge, but mongooses cannot live on Tai Mo Shan by scavenging alone and must be killing something. Rats, probably, but are they raiding bird nests? We also know little about their use of the available habitats. All Hong Kong records are from non-forest areas, but this may simply reflect the greater visibility of a low-lying animal in the open.
Please continue to report mongoose records to Porcupine! Javan Mongooses are smaller than Crab-eating Mongooses, and lack the long white patch on each side of the neck.
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