What lies behind Singapore’s crow problem? For one thing, maybe the tray return scheme
Amid rising numbers of complaints and attacks, Talking Point looks into waste management issues and control strategies for crows, with a conservationist saying that easy access to food waste is helping fuel their population growth.
When used crockery and trays are rendered accessible to crows, they can feast like a king.
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SINGAPORE: The mandatory tray return scheme, and the way it has been managed, could be one reason for the crow population increase in Singapore, according to a conservation expert.
Authorities began encouraging diners to return their trays and crockery in 2020. This became mandatory in 2021. At about the same time, the number of crow-related complaints started to rise.
And that is no coincidence, thinks Nature Society Singapore assistant director of conservation Albert Liu. “We continue to have hawker centres and coffee shops placing tray returns at the edge of (dining spaces), so open … to the birds,” he observed.
“If we can control the way we manage food waste — how we do our tray returns — there’ll be (fewer) crows in due time.”
About 15,000 complaints about crows were filed last year, triple the number in 2020. More people are also being attacked; over 2,000 cases were reported last year, up from more than 460 cases in 2020.
This crow problem has grown alongside the bird’s population size, from an estimated 7,300 crows in 2016 to about 160,000 by 2024. That is one crow for every 38 people in Singapore.
And the increase is due to the accessibility of urban food sources, Liu stressed. “Because the crows have no natural predator, … food is one of the key determinants of the crow population,” he told Talking Point.
“There’s so much food (in Singapore). And when they meet, they reproduce. … When all the food is taken out, … you’ll see the population of the crows decline.”
Speaking to programme host Steven Chia in Pasir Ris Park, he pointed out that the cawing of crows — heard every day in residential areas from Bishan to Hougang to Yishun — was absent as they walked along a mangrove trail.
“The food that crows need can be found all in the forest here,” Liu said. “But it’s hard work for them, right? They must hunt for it, … and they just prefer the urban environment.”
Across Singapore, authorities have removed nests and set traps. Last month, crow shooting resumed after a six-year hiatus. But questions remain about the efforts to catch up with the crow problem.
WHAT NPARKS HAS DONE
One of the people managing the issues with urban birds is National Parks Board (NParks) deputy director of wildlife management and outreach Gerard Lim.
And one of the possible reasons he cited for the crow population growth is that “there are more and more eateries and … food sources available” to the crows.
WATCH: Crows in Singapore — What is driving the surge and can we control them? (22:17)
There were 50,700 National Environment Agency hawker stalls, other food stalls and food shops including restaurants and eateries in 2024 — close to 5 per cent more than the number in 2020 and about 13 per cent more than in 2016.
“It’s not just the food establishments,” Lim added, citing estate cleanliness and food litter as other possibilities. “Or maybe (by) just eating biscuits and then dropping some crumbs on the floor, … this provides food sources for these crows.”
Data on estate cleanliness is collected from inspections conducted by Housing and Development Board officers. Since 2016, only once has a town council not achieved a green banding for estate cleanliness in the annual Town Council Management Report.
To keep the number of crows in check, NParks is getting rid of the next generation by removing about 30 to 60 nests each day, with three to five eggs found in each nest.
As nest removal alone has not been enough, trapping has been ramped up to target areas where crows gather and feed. Captured crows are then euthanised.
Generally, NParks can catch more than 10 crows a day in each location and up to 50 a week per location.
One resident of a neighbourhood where traps have been deployed has seen up to 20 crows trapped and thinks it is an effective method.
Still, it is not foolproof. Closed-circuit television footage of one trap showed more crows outside than the ones inside. The traps, which NParks said are cleared daily, are also not placed near hawker centres and coffee shops.
“When there’s a high footfall, it kind of spooks the crows,” said Lim, who noted that they will go for more convenient food sources that they see, “as opposed to entering a cage … to feed”.
More than 13,000 crows were caught last year — about 8 per cent of the population. “We’re constantly improving and trying to find ways to … bring down the numbers fast,” he added.
SMART CRITTERS, INVASIVE PESTS
For all these efforts, the crows are adapting. Traps can be deployed only so many times in a location — deploying them too often will result in the birds figuring out what they are, said Lim.
Bishan resident Ronnie Kuek has seen this with his own eyes. There are crows in his area that wake him up as early as 6am every day, and he has logged complaints through the Municipal Services Office’s OneService app.
“Because of the noise, we always keep our door and windows closed,” said Kuek, who has also been attacked once, when a crow swooped down on his head while he was walking.
After his first complaint in 2021, a trap was set up at the back of his apartment block. He used to see a few crows inside, “then … they stopped going in”, he recalled. “I think crows are quite smart.”
Animal behaviour expert Elias Garcia-Pelegrin, who has more than 10 research papers on members of the crow family to his name, can vouch for their intelligence.
“Social learning, (or) learning from others, is something that we don’t see … in other animals as we see in crows,” he said.
A theme park in France has even taught crows to pick up litter such as cigarette butts and put them in a box, he highlighted.
Of the various animals Talking Point has investigated, from monkeys to pigeons to rats, he would rank crows as the smartest, then “monkeys and rats together, and pigeons at the bottom”.
But pigeons “aren’t as dumb as they seem”, as they are good at pattern recognition. Rats, meanwhile, “are great at puzzle-solving in terms of labyrinths — they have great memory”. As for monkeys, they have thumbs and can use tools.
“The issue here is that crows can do all of these,” said Garcia-Pelegrin, the director of the Animal Behaviour and Cognition Lab, a research group in the National University of Singapore’s psychology department.
In some cases, they can also live for up to 30 years. “It depends on their environment,” he added. “But here, crows are healthy.”
The thing is, the species of crows ruffling feathers here — that thrives on human food, adapts quickly to urban life and is known to be aggressive, especially when nesting — is not native to Singapore.
They are house crows, an invasive species that “causes damage to our ecosystem”, said Liu, whose job is to help protect Singapore’s natural habitats and biodiversity.
“They prey on the eggs of our native birds. … They outcompete our native wildlife for food and nesting sites,” he elucidated, citing a risk to the critically endangered straw-headed bulbul, “one of the most precious birds we have”.
“We have to deal with the situation right now. … The (crow) population is huge, and if it grows any larger, there’ll definitely be negative impacts (on) our ecosystem.”
SHOOTING CROWS, NO COUNT TARGET YET
To complement the existing crow management efforts, shooting has now resumed in nine districts with a high level of crow activity where conditions allow for safe operations and where traps have proven less effective.
Kuek, who has lived in Bishan for about 20 years, observed that when shooting stopped in 2020, his problems started. The crow culling measure, which began in 1973, was halted after pellets hit homes and safety concerns grew.
So, how have safety protocols been stepped up? In a shooting operation in Jurong observed by the media this month, safety areas were marked out, and extra security officers were around to keep watch.
The shooter had to stand in a blue square, where the angles of shooting were also specified. This meant, for instance, he could not turn to shoot at crows behind him.
Members of the media witnessed six crows being shot. Another 10 crows were brought down later in the operation, which spanned an hour.
NParks director of wildlife management and outreach (urban birds) Soh Ze Bin agreed with Chia that such numbers were not really moving the needle.
“But … having more options on hand is going to enable us to sort of address this crow issue,” Soh said.
The “very big crowd” attending the shooting may have scared off the birds. “The crow shooting team is usually quite small: five to six people,” he shared.
NParks will try out different sites to see “how the crows will behave when shooting occurs”, compared with an open area in the heavy vehicle car park where the demonstration was held.
“We’ll learn from it. We’ll see what we can refine,” he said. “It’ll also allow us to select a better shooting location next time.”
NParks has not shared a specific target, however, for the number of crows it hopes to remove.
Watch this episode of Talking Point here. The programme airs on Channel 5 every Thursday at 9.30pm.
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