Jamshedpur, June 2: Can a city’s bird count impact its health? Well, if ornithologists are to be believed, it can.

Jamshedpur has shown two clear trends in terms of its avian population. One, the number of crows has dwindled to less than 5,000 now from 20,000 in the recent past. Two, the number of pigeons (also called rock dove) has increased to 10,000 from4,000 to 5,000.

And this, a city ornithologist says, can be dangerous as far as communicable diseases are concerned.

K.K. Sharma, who also heads Jamshedpur Co-operative College’s zoology department and is a member of the Ornithological Society of India (Jharkhand-Bihar chapter), says he does not want to be an alarmist.

But he adds: “Crows, as natural scavengers, clean up the neighbourhood. Less crows means more carcasses of rats, dogs and other small animals lying uneaten and festering. This apart, wastes in slum areas also lie in heaps. Together, these breed infections,” said Sharma.

Pigeons at Jubilee Park. Picture by Bhola Prasad

On the other hand, pigeons carry human pathogens. Three human diseases are known to be associated with pigeon droppings — histoplasmosis, cryptococcosis, and psittacosis.

The reduced number of crows across Jharkhand — and especially Jamshedpur — came into sharp focus from September last year as crows started dropping dead, prompting a pathogenic H5N1 virus scare.

Then, there’s always what avian experts call “social parasitism” during the breeding season where crows are particularly vulnerable. Cuckoos destroy crow eggs and lay their own. Basically, the cuckoo tricks the crow into hatching its own eggs and raising their young.

On the other hand, pigeons neither faced any virus scare nor any natural threat to breeding.

In fact, they get manmade help where food is concerned.

Though there are no kabutarkhanas (public zones where pigeons congregate to eat grain or titbits offered by humans) in Jamshedpur, in Jubilee Park, near JN Tata’s bust, morning walkers feed thousands of pigeons.

“We feed pigeons with jowar grains at our native Jaipur (Rajasthan) with a religious belief that such an act brings us prosperity. I have been doing so for the past four decades in Jubilee Park after my morning walk. In one day, I use around 700gm of jowar for this purpose. In the last two years, numbers of people doing such acts has increased,” said 76-year-old Bhawarlal Khandelwal, a grocery shopkeeper at Sakchi.

It may be a coincidence, but doctors said the number of gastro-intestinal patients had shown a spurt.

Head of the medicine department at MGM Medical College and Hospital, Nirmal Kumar said: “Patients with gastro-intestinal infections with symptoms of vomiting and diarrhoea have increased in several hospitals. Infants and elderly people have a weak immune system and are more susceptible to these infectious diseases. If neglected, they can turn fatal.”

Would avian experts link this trend to less crows and more pigeons?

“We need to be alert to the possibility. Let’s keep watch,” said ornithologist Sharma.