Calcutta: A lone Spoon-billed Sandpiper, one of the world's critically endangered species with a population of barely 450 birds worldwide, was recorded at Frazergunj in South 24-Paraganas on Sunday.

Four birders in a group of 10 from Calcutta and the districts were able to photograph the bird, making this the first known record of the species in Bengal in more than seven decades.

The website of the International Union for Conservation of Nature (IUCN) states that the bird has an extremely small population that is undergoing an extremely rapid population reduction. "This is because of a number of factors, including habitat loss in its breeding, passage and wintering grounds, which are compounded by disturbance, pollution, hunting and the effects of climate change."

The IUCN has pegged the Spoon-billed Sandpiper population at between 240 and 456 mature individuals.

The website mentions that the bird had been listed as "vulnerable" in 2000, became "endangered" in 2004 and got the "critically endangered" tag in 2008. The change in status clearly shows the decline in population and the threat it faces.

Atanu Modak, a member of the team that spotted the bird, told Metro over phone that the lone Spoon-billed Sandpiper was within a flock of Lesser Sand Plovers. "We had reached Frazergunj around 9.40am, but we spotted the Spoon-billed Sandpiper only at 12.30pm. We saw the bird for about seven minutes before it flew away and went out of sight," recounted Modak, one of the four who caught the bird on camera.

Frazergunj, about 120km from Calcutta, is a fishing destination along the Bay of Bengal and about 2km from the popular Bakkhali resort. Birders go there looking for waders and, with a little bit of luck or serendipity, something rare shows up once in a long while.

Modak said the Spoon-billed Sandpiper made an appearance about an hour after the onset of low tide. It was foraging for food in the shallow water.

A member of the team sent a picture of the bird with a bill like a fancy tablespoon to Shubhankar Patra, who leads the nature group SundayWatch. Patra turned to Sumit Sen, the honorary wildlife warden of South 24-Parganas, for confirmation.

"This is a great development. If I remember correctly, the last time a Spoon-billed Sandpiper was recorded in Bengal was way back in the 1940s. The bird is found in Bangladesh. A photograph of the bird in West Bengal extends the geographical span of the bird beyond Bangladesh," said Sen, whose website www.kolkatabirds.com is a popular resource for information on species, habitats and birding reports.

The last person to spot the bird in India before the Frazergunj surprise is S. Balachandran, a scientist with the Bombay Natural History Society (BNHS). That was in 1996.

"Balachandran found a Spoon-billed Sandpiper at Point Calimere (in Tamil Nadu). It was the last sighting in India," said Raju Kasambe, a senior official of the BNHS.

There was a previous sighting at Chilka in Odisha, Kasambe said.