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Concerns Raised Over Threat to Hong Kong's Largest Danaid Over-wintering Site by Development in Tuen Mun (6 Oct 2013)

The government has recently been exploring ways to expand urban areas, such as by developing on existing land or even reclaiming land. It plans to develop four Potential Development Areas (PDAs) in Tuen Mun. In September, the Planning Department and Civil Engineering and Development Department arranged a meeting with Green Power and other green groups to explain the PDA development plans.

There are four PDAs, assigned letters A, B, C and D. PDA-D is the site that is of most concern to Green Power, and is at the foot of Tsing Shan, Siu Lang Shui, Tuen Mun, with 23.4 hectares of land, equivalent to 32 football fields.

PDA-D is only 500m away from former Siu Lang Shui Landfill (SLSL). The former SLSL is a well-known site for over-wintering Danaids, with a peak record of 40,000 overwintering butterflies. It is the only Site of Special Scientific Interest (SSSI) in Hong Kong designated for the protection of over-wintering Danaids. Although recent records show that there was a slight decline in the number of overwintering Danaids, with numbers falling as low as 100, Green Power's butterfly survey shows a recent upturn, with around 600 in 2011 and 6,000 in 2012.

According to Tuen Mun Outline Zoning Plan, around 60% of PDA-D is assigned as Green Belt zone; the remaining 40% is government, institution or community land uses. The planning intention of the "Green Belt" (GB) zone is primarily to promote the conservation of the natural landscape and vegetation, and to safeguard it from encroachment by urban-type developments. The green belt should serve as a buffer between Siu Lang Siu SSSI and urban area. Therefore, although some of the PDA-D is designated for government, institution and community uses, the scope and scale of development must be regulated and supervised. To date, the government has not yet announced the development plans for PDA-D. Green Power expresses concern about potential large scale development in PDA-D.

Maolin, Taiwan, which is a famous site for overwintering Danaids, used to host several hundred thousand overwintering Danaids. Yet, a few years ago, car parks were built in nearby areas, disturbing the habitats. The Danaids no longer over-winter in the ravine. This case shows that construction and frequent human activities adversely affect overwintering Danaids. Similar examples can be found at Hong Kong' Fung Yuen. This is an SSSI for butterfly conservation. Due to a recent nearby residential development, sunlight is blocked by high-rise buildings, leading to a decline in numbers of butterflies. This shows that the approval of a development project's Environmental Impact Assessment (EIA) cannot guarantee that butterflies will be unaffected. Therefore, the impact of development on Siu Lang Shui overwintering site must be thoroughly considered in the PDA-D development plan.

Green Power urges the government to consider both short-term and long-term impacts on overwintering Danaids arising from construction and utilization of facilities; and avoid construction work during the overwintering period of Danaids. However, the best approach is to re-plan and re-design PDA-D, and exclude the western part of the former landfill from the area.

Location Map of Potential Development Areas (PDA)


Original scene of PDA-D
Former Siu Lang Shui Landfill
Danaids wintering in Siu Lang Shui, Tuen Mun


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