It was first seen this winter in a pond in the Grand Canal Forest Park in Beijing's Tongzhou district on Dec 26. But after most, if not all, freshwater bodies including reservoirs and ponds froze due to the sharp drop in the temperature in early January, it, along with other waterbirds, moved to rivers which remained relatively ice-free due to the water flow.

It was last sighted on the Wenyu River on the border of Chaoyang and Shunyi districts of Beijing.

The scaly-sided merganser, also known as the Chinese merganser, is a species of migratory bird with only about 10 sightings in Beijing－and the first in Tongzhuo district according to news reports. The species is under first-grade State protection and classified as "endangered" on the International Union for Conservation of Nature's Red List.

Scaly-sided mergansers are endemic to East Asia, breeding along rivers in the mountainous areas of northeastern China, the Russian Far East and probably the Democratic People's Republic of Korea in the summer, and wintering in water bodies in mainly eastern and southern China and the Republic of Korea. The species, mainly distributed in China, is estimated to number about 2,000.

Do the increasing sightings of rare birds such as the Chinese merganser in Beijing's parks and water bodies mean an obvious improvement in the local environment? A colleague who knows I've been an avid birdwatcher for years asked the question.

While I may know a bit more about Beijing's birds and environment than my colleague, I cannot say for sure the sighting of the scaly-sided merganser does necessarily indicate an improvement in Beijing's environment. But based on what I know and have seen, the environment is indeed better than what it was some years ago.

There is more green cover in neighborhoods. And more parks have come up across the city. Some bushy stretches of land on the shores of many of Beijing's lakes and reservoirs have now been fenced and closed to visitors including anglers, and people in general have become more bird-friendly. For example, the land around Shisanling Reservoir in Changping district was fenced several years ago－and probably because of that, several sightings of rare birds, some rarer than the scaly-sided merganser, have been recorded there over the past two years.

Also, seasonal farming, mainly of corn, on the wide stretches of land around Beijing's largest reservoir, Miyun Reservoir, was banned several years ago－and the whole area was fenced and closed to visitors. Although I haven't been there on bird-watching trips since, I can imagine the area being transformed into a haven for migratory birds, with many more rare species wintering there. Perhaps more environmentally friendly wintering habitats have been drawing more birds, including rare ones, to the city.

But for me, the more obvious reason for the increased sightings of rare birds is the rise in the number of birdwatchers. Bird-watching or bird photography has become a popular hobby among Beijing residents. Groups of senior bird photographers gather around lakes or reservoirs in the city every week.

About 10 years ago, when my friends and I used to visit birding sites on the outskirts of the city on the weekends, we often found ourselves alone. Now if you go to a birding site on the weekend, you have a good chance of meeting other birdwatchers.

With the number of birdwatchers increasing, "good records" (meaning sightings of rare birds) have become more frequent and many winter habitats for birds are now much safer－meaning fewer threats from poachers and human interventions to the birds. And a safer, greener environment will naturally attract more birds.

But some ornithologist friends say that more birds flocking to one place could also mean the loss of their winter habitats in other areas. For example, when land reclamation and environmental degradation led to the loss of many intertidal mudflats and coastal wetlands in eastern China, migratory birds were seen flocking to some surviving sites along the coast in increasing numbers.

But indeed it's a blessing to enjoy the company of more feathered friends in the city amid the shadow of COVID-19.

The author is a writer with China Daily.