On the verge of vagrancy: What rare bird sightings mean

Spotting a rare bird in a rarer geography is every birder’s joy and pride. Recently, birders at the Sultanpur National Park in Gurugram, Haryana experienced this delight as they spotted a Marbled Duck, a Baikal Teal and a Falcated Duck.

The experience raised a question: Why are there so many rare sightings this season?

Here, the star of the story is the celebrated Falcated Duck. The sightings of the Falcated Ducks in India are irregular and can be termed as 'rare'. Often, a single individual has been spotted at certain places in North India.

Though many available records indicate the bird had visited northern India from time to time, the frequency of winter migration to Sultanpur has diminished substantially in recent times.

Most of the time, only a single bird descended at the park and probably the rest (if there are any) moved ahead towards the northeast Indian region, which is the preferred wintering ground for Falcated Ducks.

Many questions bother me: Did this bird embark on its migration journey alone? Or was this one separated from a flock due to some reasons and covered an arduous journey on its own?

If a bird gets separated from its group under some unavoidable circumstances and is found in an unexpected place which is not its normal range of occurrence, it is called a ‘vagrant’. The Falcated Duck is not a vagrant in India. India is the wintering ground for the species.

The gradual decline in the number of migrations over a period of a few decades led me to wonder if they are on the verge of vagrancy! (Especially those who know about the accelerated extinction of the avian species due to anthropogenic consequences will easily relate to my concerns.)

Why and how does a bird become vagrant? What happens to such birds? Do they successfully return to their family / flock or perish somewhere in between the wintering and breeding grounds?

There are many reasons due to which a bird becomes a vagrant. Powerful storms, for instance, often transport birds to a far-off region which is not their usual range of occurrence. Then, any kind of anomaly like a space storm can disrupt Earth’s magnetic field, causing errors in birds’ navigation.

Deviation in migratory orientation due to the 180-degree flip of the sense of direction can play a role too. As a result of this, the bird may take the opposite route to the one it has to follow.

Another factor can be the wrong assessment of the length of the migration, which is termed as ‘overshoot’. This means the bird moves far ahead of the destined landing place.

Sometimes, a single bird joins a wrong group which is nearly similar to its own species and ends up landing at a wrong destination, which is termed as ‘group entrainment’.

Migrants, exhausted by flying over vast stretches of water, desert flats or mountain ranges for many hours, fly towards the nearest good patch of habitat to rest and refuel before moving towards their destined grounds.

Finding a vagrant is always exciting but most of these birds cannot return successfully to their native areas. There are many reasons.

First, due to predation by other animals or raptors at an unknown terrain. Second, the harsh weather of the unknown place may not be suitable.

Third, if the bird has been exhausted at arrival and couldn’t manage to get enough food timely to regain its lost strength, it may perish.

Fourth, if it gets affected by some pathogen or avian disease at the foreign land then death is inevitable.

Finally, in an unfamiliar habitat a vagrant bird may die from the stress caused by humans.

Still, there is some hope because all vagrancies are not a result of calamity, but a well-planned migration to expand the range boundaries by a particular species. The first individual of a species pioneers the range expansion by dispersing to a distant place, which is later followed by the expanding population to colonise the area.

Probably this is not the case in Falcated Duck, because then we would have seen an increase in the number of winter migrants at different places in the subsequent migration records. In particular, there may have been a sharp increase in the number of Falcated Ducks arriving in winter in north Indian states such as Punjab, Uttarakhand, Haryana, Assam, West Bengal and Himachal Pradesh, where more sightings have been recorded. 

Moreover, this species has been categorised under the ‘Near Threatened’ category by the International Union for Conservation of Nature, which implies that their number is declining globally.

It is unclear which of the above reasons brought the Falcated Duck to Sultanpur this year but looking at the good physical condition of the bird, it can be assumed that it has come to rest and refuel.

The individual did not display any kind of physical stress during my observation but was rather foraging happily along with other ducks.

Probably it is the healthy ecosystem of Sultanpur National Park that attracted this otherwise tired and famished duck due to the long journey! This park is a part of the Central Asian Migratory Flyway that provides food, shelter and breeding grounds for many species of birds. It is a stopover site for thousands of migratory birds from Central Asia, Siberia and Europe, at which the distant migrants refuel themselves before moving to their usual wintering grounds.

Inside the park, grasses, aquatic plants, seeds and roots, along with aquatic insects and molluscs, are plentiful, and these are the favourite food of all the dabbling ducks, including the Falcated Ducks.

So, I assume that the ducks might have landed at Sultanpur National Park and stayed for a few days just to regain their lost strength and gather enough energy / fat to resume their migration journey.

Let’s be mindful and make it a point not to disturb or harm these precious visitors and wish that these lone birds should get back to the safety of its flock as soon as possible!

Views expressed are the author’s own and don’t necessarily reflect those of Down To Earth.