Kenyan farmer Danson Safari was forced to give up poultry rearing after losing hundreds of chickens to attacks from aggressive Indian house crows which are multiplying along the country's coast, reported Reuters.

The growing threat has prompted Kenyan authorities and conservation groups to turn to a chemical called starlicide to eliminate the pests while minimising harm to other birds.

The invasive species was originally brought to East Africa from the Indian subcontinent in 1891 and researchers estimate that they number almost one million in Kenya today.

The crows have dramatically reduced the populations of birds native to Kenya, said Kirao Lennox, research scientist at conservation group A Rocha Kenya.

"They are now predating on our indigenous species, targeting nests, eggs, chicks, and even adult birds," Lennox said. "Without natural predators to keep their numbers in check, they are overwhelming the ecosystem, leading to the decline of native species."

Since being deployed, the starlicide has killed around 200 crows in a month in the coastal town of Watamu, said Eric Kinoti, a crow control officer at A Rocha Kenya.

Kinoti said the crows have also been seen along the road connecting the port city of Mombasa to Nairobi. He fears the crows could decimate biodiversity within Kenya's capital city, especially in Nairobi National Park, home to hundreds of bird species.

"We don't want them to get to Nairobi," he said. "When they enter into that ecosystem, they are going to totally eliminate the other bird species."