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Bins aim to curb monkey business

October 18, 2015

Treasure hunt

Treasure hunt:  Monkeys raid and upend trash bins in search of food, scattering litter that attracts wild boar, dogs and crows scrounging for snacks.

Rubbish revolution

Rubbish revolution:  To combat wildlife scavenging through the trash, bins have been undergoing constant redesign, from the original plastic buckets (right), through several iterations to the latest animal-proof pedal-activated disposal unit.

Clever clasp

Clever clasp:  Hong Kong Polytechnic University designed this foolproof system that requires two simultaneous actions to unlock – a challenging manoeuver for a monkey.

Pedal power

Pedal power:  The latest bin model requires the user to step on a pedal to open the chute to deposit trash – safely out of monkeys’ reach.

Restricted diet

Restricted diet:  Senior Field Officer KM Law and Country Parks Ranger Services Officer Angela Chan suggest the most effective way to prevent animals from foraging through trash is for people to leave no trace of their visits by taking litter with them when they leave.

Hong Kong’s country parks draw more than 11 million visitors every year – who leave behind 3,800 metric tonnes of trash. There is a two-pronged strategy to end the resulting rubbish piles: newly designed animal-proof bins, and a campaign urging visitors to take their litter home.


The existing overflowing litter and recycling bins are a magnet for wild animals scavenging for food. Agriculture, Fisheries & Conservation Department Senior Field Officer KM Law says monkeys, with their human-like limbs and opposable thumbs, are the worst culprits, joined by wild boar, dogs and crows.


“Monkeys raid the garbage and upend bins in search of food, leaving trash scattered everywhere, which makes clean-up work tedious,” Mr Law said. It also affects the natural environment.


He has been working with the department since 1979 and is responsible for managing country parks. In recent years, he said, monkeys have been developing an addiction to salt and sugar after gorging on leftover potato chips, soft drinks and biscuits - which may harm their health and upset the ecological balance.


“Monkeys eat flowers, leaves and fruit in nature, maintaining nature’s balance as seed dispersers. If they only scavenge for food from bins, then seed dispersion would be reduced.”


To prevent wild animals from raiding the garbage, over the years, the department has designed different animal-proof bins to replace the original open plastic buckets that had unwittingly invited animals to help themselves and were easily toppled over.


“We added a tall cylinder at the top of the bins in the first modified version, to prevent monkeys from reaching in to get the trash. Then we spotted some clever monkeys hanging down inside from the top, reaching with their upper limbs to grab the food.”


Having outsmarted the bins’ designers, Mr Law and his team adjusted their thinking. They made reference to North America’s experience in resisting black bear raids on rubbish to design a bin that is truly wildlife-resistant thanks to special hinged chutes, a pedal, and a monkey-safe locking system.


“To put trash into the bins, visitors must step on a foot pedal to open the chute and place it on a hinged platform which drops the garbage down the chute before closing,” Mr Law said.


Even if a monkey is able to learn to use the pedal, it won’t be able to access the trash, he says.


To prevent monkeys from upending the bins to search for food, the department invited Hong Kong Polytechnic University to design a special clasp. To pull the trash box out requires two simultaneous actions: removing the clasp and lifting the box up. That is a difficult manoeuver for even the most clever monkeys.


The new bin was placed in Shing Mun Country Park for six months, and was found to effectively stop monkeys accessing the rubbish. The department plans to mass produce them and place them in the Kam Shan and Shing Mun country parks – where monkeys are most prevalent - next year.


Source reduction

Although the department has placed nearly 4,000 rubbish bins of different models in country parks, items left behind by visitors or dumped around overflowing bins affects the natural environment and alters animal behaviour, making them dependent on leftovers.


To counter this, the department recently launched a campaign encouraging park goers to take their rubbish home with them. Country Parks Ranger Services Officer Angela Chan explains why.


“Nature is powerful. Leaves are recycled and composted into soil nutrients. But if visitors discard items like plastic bottles, food packages and foam containers, they can be easily swept over the mountainsides or valleys and into reservoirs and coastal areas, which is difficult to clean up,” Ms Chan said.


“Hikers should properly dispose of their litter outside the country parks. Everyone can help to waste less and protect the environment.”

Waste Reduction