The crooked upper bill of a crow has generated considerable interest among the community of ornithologists. An adult crow with a crooked upper bill was recently spotted at Mankavu near Kozhikode. The bird was photographed by T.V. Sajeev, an entomologist of the Kerala Forest Research Institute. “The picture of the crow had generated huge interest in the internet community and several people have reported sighting such crows,” Dr. Sajeev said.
Though it is difficult for the animals with such deformities to survive, the bird has developed a sub-niche for itself and was found feeding, though with some difficulty, he said. Crows are the birds which have not been studied and photographed much. One needs to look into the scientific aspects of the deformed upper mandible. The question whether the particular bird belonged to any sub species of the crow or the deformity was passed on to generations needs to be looked into, Dr. Sajeev said.
Satyan Meppayur, vice-president of the Malabar Natural History Society, Kozhikode, had also spotted and photographed another crow with such deformity from the Parambikulam Wildlife Sanctuary a few years ago.
“There was information that the upper mandibles of some Red-Billed Blue Magpies, which belonged to the crow family and was found in the Himalayan region, had similar deformities,” Mr. Satyan said.
The Himalayan cousins of the crows feed on the honey of forest flowers. Till now, no information on the reasons for the deformity has been reported. Studies on the genetic aspects of these birds need to be carried out for ascertaining the reasons for deformity, he said. Jafar Palot, Senior Scientific Assistant of the Zoological Survey of India Western Ghats Field Research Station, Kozhikode, had also spotted such crows.
“We had observed similar birds from Kannur and Kozhikode cities in the recent past. It was so sad to see foraging of these birds with malformed larger upper mandibles,” Mr. Jafar said.
P.O. Nameer, Associate Professor (Wildlife) & Head, Centre for Wildlife Studies College of Forestry, Kerala Agricultural University, Thrissur, said that it was a case of bill deformity due to calcium deficiency or the exposure to the synthetic chemical and environmental contaminant, Polychlorinated Biphenyl or a combination of both.
The pollutants in the atmosphere might have entered into the food chain of the bird leading to the deformity. The bill-deformed birds would find it difficult to feed and preen and this could ultimately lead to the death of the bird, said Dr. Nameer who is also the South Asian coordinator, Conservation Breeding Specialist Group, Species Survival Commission of the IUCN.
R. Sugathan, renowned ornithologist, also opined that the exposure to chemicals and pesticides might have caused the deformity. Then, there is also the possibility of congenital deformity as found in other animals. DNA analysis needs to be carried out for discovering the reasons of such deformities, Dr. Sugathan suggested.