The natural environment is often fragmented by human activities. The most obvious example is the building of highways. Long roads cut through large tracts of forest, dividing them into two. Animals’ habitats are thus fragmented, affecting the feeding, mating, populations and migrations of many species.
Many countries attempt to build animal passages to help species cross the fragmented habitats. For example, in Canada’s Banff National Park, overpass and underpass corridors were constructed above and under the highway, respectively, to allow large mammals (e.g. coyotes, grizzly bears, etc.) to freely cross between the two sides of the highway without the risk of being hit by vehicles.
Similar animal passages can be found in Hong Kong. The first such example is at the Ting Kau end of Tai Lam Tunnel along Route 3. A tunnel with a staircase connecting to the ground surface was supposed to allow wild animals such as Masked Palm Civet (Paguma larvata) and Red Muntjac (Muntiacus muntjac) to reach both sides of the tunnel.
However, the effectiveness of animal passages depends on various factors. The above mentioned tunnel in Hong Kong is a failure due to wrong choice of location, size and materials. In seven months, only two Masked Palm Civets were recorded using the tunnel. Researchers point out that the tunnel is too narrow, materials too unnatural and with fences nearby – factors which all lead to low usage of the animal passage.
Urban development has continued to invade the countryside, and habitats for wild animals are dwindling. It is particularly important to protect wild animals from impacts of development in Hong Kong due to the pressure from population growth in the limited land area. Animal passages can help species with foraging, reproduction and migration if carefully planned. Yet without targeting the animals' needs, an "animal passage" will only serve as pretence, justifying development.