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House Crows a big threat to tourism, the environment and human health

By Caroline Chebet | January 4th 2021 at 07:00:00 GMT +0300

Indian House Crows hover above mounds of garbage at Mwakirunge dumpsite in Mombasa County. [Kelvin Karani, Standard]

Residents of Mombasa, Malindi, Watamu and Kilifi have all encountered the annoying and invasive Indian House Crows.

If not chattering noisily at dawn to awaken the neighbourhood, they are hovering above waiting to swoop and dive-bomb on eateries or snatch food in homes.

They can also be spotted chasing other birds or hunting their nestlings or even rummaging through garbage for a meal before finally retreating to their safe spaces at dusk.

Experts describe the Indian House Crows as invasive pests. Though they are not indigenous to East Africa, they rule the skies in Coastal towns and are a nuisance.

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Loves garbage

The House Crow, also known as Indian House Crow, thrives on the garbage and originated from India, as the name suggests. Experts say the birds gained entry in Mombasa in 1947 as stow-aways on ships or spread from the neighbouring coastal town of Zanzibar. Although the birds are non-migratory, they stow away in ships, often landing in coastal towns away from their native ranges.

“Indian House Crows are invasive and are ruling the skies in coastal towns of Kenya. They thrive on garbage but have become a nuisance, getting into hotels and grabbing guests’ food. The birds are also displacing other native species that once thrived in those areas by raiding their nests and feeding on their young ones,” Paul Gacheru, a species expert at Nature Kenya says.

With the House Crows having no natural predators in Kenya and their ability to adapt to new environments quickly, they increased exponentially in numbers.

By 1980, the birds had spread inland to Mariakani, south to Diani and north to Kilifi Creek. By late 1980s, the birds were already in Malindi and now thousands are found in Mombasa.

By 2011, the first House Crows were seen inland at Voi town and by 2013, the same were spotted in Makindu.

Impact on bird diversity

But given their negative effect on the environment, they are now a cause for concern, according to conservationists.

 “There is concern that these birds, which are dependent on human habitation and garbage, are fast displacing native bird species at the Coast. Bird counts have shown a declining population of other species within the Coast while there has been an increase in the population of Indian House Crows,” Gacheru says.

The biggest concern, he says, is that the birds’ population is growing and they are spreading to other counties beyond Coast.

“Tsavo National Parks acted as a barrier since there is no human habitation and garbage to let them thrive. However, the birds seem to be getting inland following the main highway and have since been spotted at Sultan Hamud. The fear is they are now getting into other towns where controlling the population remains a challenge,” Gacheru observes.

Threat to agriculture

According to the National Indian House Crows Eradication Programme, the birds have caused negative impacts on agriculture, environment, tourism and public health sectors.

House Crow is also classified as an invasive species in the Wildlife Act, 2013. The Ministry of Tourism and Wildlife acknowledged that the birds affect people and livestock through spread of disease, causing damage to farms, infrastructure and wildlife and impacting tourism negatively.

National Indian House Crow Eradication Programme also notes that while Tsavo National Park has for many years served as a barrier to the birds, petrol stations, hotels, restaurants and food kiosks along the highway was encouraging their spread.

Additionally, the building of the Standard Gauge Railway has also created a suitable habitat to enhance their spread.

Poison to kill them

Between 1999 and 2005, A Rocha Kenya, a conservation organisation piloted the use of a special poison designed to kill avian pests to eradicate the invasive Indian House Crows.

According to Colin Jackson, A Rocha Kenya director, the poison - Starlicide - worked well to control the population of the birds within the period. The government, however, banned the poison in 2005, a move that has since seen a rise in population and spread of the birds.

“Starlicide has worked well in other countries in the eradication of the invasive birds. The poison is only designed to eradicate invasive birds and there are no secondary deaths resulting afterwards. The poison is expensive and we have since done a proposal for funding to eradicate the birds,” Jackson said.

By the time the government banned the importation and use of the poison, population of Indian House Crows had been controlled down to six birds in Watamu and between 25 and 30 birds in Malindi.

According to the Centre for Agriculture and Bioscience International (CABI), the invasive birds have since established populations in 24 countries outside their native range. They have also been documented in 23 other countries in which they are yet to become established.

The organisation noted that House Crows have a history of ruling over urban areas before spreading further into human settlements, harassing native species and acting as carriers of human and animal diseases as they rummage dumping sites.

CABI noted that though Starlicide has been widely used to eliminate House Crows in several countries with success, funds are often a limiting factor as with the Kenyan case.

“Use of Starlicide has proven highly successful in House Crow control where populations are large, but such programmes in Kenya and Tanzania have been halted due to funding problems and lack of access to Starlicide,” CABI noted.

Other options that have been employed by the locals in eradicating the bird included trapping, nest destruction during the breeding season as well as shooting. Long-standing restrictions on the importation of Starlicide and a failure to reduce garbage availability, according to Jackson, has resulted in the increasing populations with rising concerns that they might soon be spreading to other towns.

Global monitoring

The current strategy, Jackson said, is to prevent the Indian House Crows from spreading to other towns and cities like Nairobi, where they will be hard to control.

As part of global monitoring of the bird that is rapidly spreading across coastal towns, a website, www.housecrow.com has been established to monitor invasions.

The website is part of a 30-year-long programme to monitor the continuing world-wide invasion of the House Crow, as well as assessing its status in places where it has already established.

Travel on ships

According to the website, House Crows travel on ships, often over thousands of kilometres so they could turn up on almost any coast in the world that is close to major shipping routes, most likely in ports, peninsulas and fishing villages.

House Crows, the website notes, are already well-established in East and South Africa and many parts of South East Asia.

“They could arrive anytime at ports in Indonesian islands, the Philippines, New Zealand, Japan, Coastal USA, the Caribbean Mediterranean Coast and islands and additional ports in Africa and Europe. They are spreading overland in Southeast Asia and could turn up anywhere in Laos and Cambodia, and extend their range in Thailand, Vietnam, Sumatra and Borneo,” notes the website.

Being omnivorous, House Crows feed primarily on refuse supplementing their diet with stolen food and raiding nests and predating on small marine animals. They also forage for insects, picking ticks and opening up wounds on livestock as well as picking up and eating discarded fish. Their undying commitment to live alongside humans has seen them foraging in markets, parks, gardens, homes and public areas.

As part of the solution, Kenya Wildlife Service among partners including National Museums of Kenya, A Rocha, Nature Kenya, Pests Control Products Board, Nema, Kenya Airports Authority among other organisations have been discussing viable ways to control the invasive birds.

A National House Crow Control Committee has also been formed to oversee efforts to control House Crows in order to bring to tolerable levels their negative ecological, biological, agricultural and economic impacts.


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