In a first, NParks trials use of dead bird effigies to prevent crows from congregating, Singapore News

AsiaOne

2 days ago

SINGAPORE - Hanging upside-down from a tree branch, the full-feathered "crow" was limp, its eyes devoid of any signs of life.
The dead bird, however, is not real, but just a plastic effigy.
It is part of an ongoing trial by the National Parks Board (NParks) to prevent murders of house crows (Corvus splendens), considered an invasive species here, from congregating in large groups.
Such effigies have been tested overseas in places such as the US with some success, and NParks is testing them out here for the first time as a tool to disperse these birds.
In response to queries from The Straits Times, Mr How Choon Beng, NParks' group director of wildlife management, said: "The effigies are placed at roost sites and positioned to resemble dead crows. The aim is to create a perception of danger and encourage the roosting crows to disperse to other locations."
The realistic decoys were first deployed in Singapore in late 2023, with each effigy deployed at a site for about two weeks on average, NParks said.
Since 2023, a total of 15 effigies have been put up across eight locations that are heavily populated with crows, or experience higher volumes of disturbances by crows.
NParks shared that it received an average of nearly 7,000 cases of crow-related feedback annually from 2023 to 2024, relating to issues such as noise, sightings, attacks, feeding and soiling.
The board did not reveal the exact locations of the set-ups, but The Straits Times had observed one effigy deployed on a tree outside Katong V mall in April.
"This is a plastic crow. Please do not be alarmed," read a sign next to the tree where the effigy had been deployed. That effigy was taken down on April 24.
As data collection is still ongoing, NParks said it was unable to provide further details.
Trials of these crow effigies come after news of these birds flying at and pecking passers-by.
Between February and March 2023, there were reports of crow attacks in Bishan and Serangoon, with some 10 passers-by getting hit or having crows swoop right by them in a 20-minute span near Block 110 Bishan Street 12.
Another crow attack at Block 485B Tampines Avenue 9 in July 2024 led to the removal of 77 crow nests from a stretch of trees in Tampines.
There were also cases of crows attacking humans outside Orchard Central mall in October 2024. Two birds attacked about 10 individuals in the span of an hour, ST observed, with one victim sustaining a bleeding earlobe.
A 2008 scientific paper by the National Wildlife Research Centre of the US Department of Agriculture (USDA) Wildlife Services had cited an earlier paper that suggested that dead crows, when hung on fences or from trees near fields, "can be effective for months".
That study had also suggested that "crows readily associate death and danger with places where their brethren have died".
The USDA researchers then sought to test out their hypothesis that effigies could be an effective tool in dispersing crows. Each effigy was suspended upside down from a prominent branch near the top of a centrally located roost tree.
Ahead of the winters of 2005 and 2006, the researchers installed effigies of dead crows in wooded areas of Lancaster in Pennsylvania, the US, where up to 40,000 crows would roost together.
The first effigies were put up in November 2005, and by January of the following year, the crows had split into smaller roosting aggregations.
Prior to the return of winter in October 2006, the researchers installed the effigies again, and observed that the area was used only sparingly by crows throughout the second winter.
The researchers concluded that this tactic was effective in dispersing large numbers of crows at large roost sites away from the effigies.
However, they also noted that crows are observant and wary of changes in their environment. Some crows occasionally returned to roost sites at night when the effigies were not as visible.
House crows are common residents in cities and towns, and thrive in urban environments.
In Singapore, these black birds can often be found at food centres and rubbish bins scavenging for leftover food. Their cawing and droppings can bring about inconvenience and unsanitary conditions when gathering and roosting, especially near residential areas.
During the fledgling season between May and June, adult house crows get extra protective and may attack humans who come close to their young. The fledgling season is the period when young birds develop their ability to fly.
Nature Society Singapore's bird group told ST previously that house crows pose a threat to local biodiversity as they are known to prey on the Malaysian plover, a critically endangered bird native to the Republic.
Vice-president of research and conservation group Bird Society Singapore Movin Nyanasengeran noted that the practice of deploying crow effigies is common enough that one can buy such decoys easily online.
"It will probably be effective, at least initially. Crows are, however, very intelligent, so it's tough to say if it will remain effective over time... but it is definitely preferable over shooting or poisoning the birds, and is unlikely to lead to any detrimental impacts on its welfare," added the PhD student, who studies bird species distributions at NUS.
He added that it is difficult to predict when the crows would eventually learn that the decoys are harmless and do not indicate danger, before returning to roost.
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The crow effigies add to a suite of measures already being implemented to manage crow populations in Singapore.
These include removing nests and sources of food, modifying their habitats to make them less conducive for roosting and trapping the birds.
"NParks adopts a holistic and science-based approach to managing pest bird species... (and) conducts studies to understand the ecology of the birds, such as their roosting patterns and movements," said NParks' Mr How.
Those who wish to provide feedback on crows in their neighbourhoods can contact NParks' Animal and Veterinary Service on 1800-476-1600 or submit an online feedback form at https://www.avs.gov.sg/feedback How to control crow populations Avoid feeding crows. Under the Wildlife Act, offenders can be fined up to $5,000 for their first offence of feeding any wild animal, including crows, and up to $10,000 for subsequent offences. Mr How said NParks also monitors feedback on illegal bird feeding and undertakes active enforcement, which includes physical surveillance and the deployment of CCTV cameras at identified feeding hotspots.
Fruits in trees planted in landed property should be harvested or covered with an opaque material. This is because crows are omnivores and feed on insects, fruits, vegetables, rubbish and carcasses.
hose living in houses near hotspots where crows roost should remove water sources in their yards, as they may present a stable drinking source for the birds.
Pet owners should remove unfinished food and spills if they feed their pets outdoors. Ideally, pets should be fed indoors.
Residents of landed property can consider playing recordings of crow distress calls multiple times a day, or stringing up shiny metal pieces, such as CDs, to reflect sunlight and disperse roosting crows. However, this method may not be effective for long, as crows are intelligent birds.
This article was first published in The Straits Times. Permission required for reproduction.