- Crows are now seen even in wilderness havens such as Horton Plains
By Malaka Rodrigo
Crows have long had a reputation of being a nuisance and a pest, even though it’s widely recognised that they’re among the most intelligent of birds.
In Sri Lanka, that reputation goes back some 2,000 years, to the Jataka morality tales from the Buddhist tradition. One of the tales is of a “greedy crow” that spies a half-covered plate of fish in a nobleman’s kitchen and tries to steal it, only to be caught, have its feathers plucked, and thrown out. The moral being, of course, that greed is bad.
But if the modern-day crows of Sri Lanka are any indication, it would be safe to assume that the crow in the Jataka story ended up just fine, ever hustling and thriving — the perfect avatar for the International Crow and Raven Appreciation Day which fell yesterday (27).
Sri Lanka is home to two crow species: the large-billed crow (Corvus macrorhynchos) and the house crow (Corvus splendens), also known as the Indian crow, a common bird found throughout much of South Asia. (The house crows found in Malaysia’s Penang State are thought to come from a population of 56 birds brought over from Sri Lanka in the 1890s for caterpillar control.)
While the large-billed crow abounds in rural settings in Sri Lanka, the house crow occurs mostly in cities. One thing they have in common, though, is that both thrive on trash, flocking to the many open dumpsites around the island. Another thing: both are among just seven bird species that aren’t protected under Sri Lankan law; the vast majority of the around-500 bird species found in the country are protected.
Thriving on trash
Colombo, Sri Lanka’s commercial capital, appears to have the country’s biggest crow population. The Field Ornithology Group of Sri Lanka (FOGSL), the local affiliate of BirdLife International, initiated a study on Colombo’s crows in the late 1970s, and the effort continues today.
“Our study showed that garbage is directly linked to crow population fluctuations,” FOGSL President and University of Colombo Professor of Zoology Nihal Dayawansa, told Mongabay.
Crows have communal roosts, often a single tree, or several in the same area, depending on the size of the flock. This makes it easy to carry out a population assessment, which the FOGSL researchers perform through roost counts at dusk. Over the decades, they’ve recorded the Colombo crow population growing from about 50,000 birds in 1980 to a peak of 124,300 in 2006, before dropping below the 100,000 mark, at 98,350, in 2012.
The turning point, Dayawansa said, was the Colombo Beautification project in 2010, which included the shut down of several open dumpsites that were considered eyesores. But after 2014, the Government largely abandoned the project, and new dumpsites began appearing.
The Colombo crows are predominantly house crows (only about 5% are large-billed crows), roosting in flocks of as many as 500 individual crows – although figures like this aren’t common anymore, Dayawansa said.
Impact on endemic wildlife
The inspiration to begin the crow study came from a public market near a school where the birds had become a nuisance, said ornithologist and University of Colombo Emeritus Professor of Ecology Sarath Kotagama.
“This market got shifted to another area and the crow population in the area too declined,” Kotagama informed Mongabay.
Over the years, the study has confirmed that crows move with the garbage. And it’s not just open dumpsites that make for easy pickings. In Horton Plains National Park, one of the most ecologically sensitive areas of Sri Lanka and a UNESCO World Heritage Site, large-billed crows swoop in with every surge of human visitors, thanks to the large amounts of trash that the latter generate.
When visitor numbers to the national park drop significantly, as was the case throughout much of the Covid-19 pandemic, the crows lose their main source of food and begin hunting native species, which includes endemic species like the Ceylon deaf agama, a lizard found only in Sri Lanka. This development raises concerns about the impact on native species if the crow population increases unchecked, Kotagama said.
Dayawansa said that crow populations can be controlled through the management of food resources that are available to the birds. This means an effective garbage management strategy, he said. Some countries, such as Singapore, have crow-culling competitions and other methods to eradicate the birds.
But if there’s an alternative moral to the Jataka tale from 2,000 years ago, one that applies to the present-day problem, it’s that the plate of fish in the nobleman’s kitchen should have been fully covered to begin with.
“Implementing artificial population control methods such as destroying eggs and culling of adults would not be necessary, if garbage sites are better managed,” Dayawansa explained.
The writer is a naturalist with an IT background who took environmental journalism in 2007 to follow his belief in “conservation through awareness”. He has won many awards for his work and writes extensively on biodiversity, wildlife, oceans, water, climate change, and environmental issues.
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(This article was first published in Mongabay, a nonprofit environmental science and conservation news platform that has over 800 correspondents in some 70 countries)