The Common mynah ruled the roost in Singapore 30 years ago, topping the Nature Society (Singapore)'s or NSS' one-day census of birds in the country in 1986.
But since then, the small black and brown bird has suffered a dramatic reversal of fortunes, losing its lofty perch to a relative, the Javan or White-vented mynah.
The Common mynah's fall has been so steep that NSS volunteers counted just 28 of them in the latest census last month, compared with 543 in 1986.
Although the NSS and birdwatchers said field studies are needed to uncover the cause, they noted that the Common and Javan species are ecologically similar and most likely compete for the same resources.
This fight for dominance within the mynah family is just one of many facts about the bird kingdom here revealed by the NSS' long-term data.
Since April 1986, the society has conducted a one-day, islandwide census every year.
The 1986 count spanned 30 sites, which included parks, nature reserves and other green spaces here, such as Botanic Gardens.
The latest census covered 26 of those sites as fewer volunteers were available.
Mr Lim Kim Seng, 54, helped to coordinate the latest count. The nature guide and part-time lecturer said the 30 years' worth of data has been "very valuable in telling us about the changes in Singapore's ecology".
The House swift, for example, has declined even more spectacularly than the Common mynah, and may be in danger of disappearing here altogether. It was ranked fifth in the 1986 census with 281 counted but, last month, the volunteers saw just two.
"This was due to the boom in swiftlet farming in South-east Asia, particularly in Malaysia and Indonesia," said Mr Lim.
The swiftlets, a relative of the House, are valued because their nests are used to make the bird's nest soup delicacy. Mr Lim said it is likely that the swiftlets flew to Singapore, fought the House swifts for dominance and won.
The Pink-necked green pigeon, on the other hand, has climbed the ranks over the years. It ranked No. 7 in the 1986 census with 213 sightings, but was No. 3 this year with 464 counts.
"It appears to be benefiting from the aggressive tree planting in new towns and regional centres, especially of trees with fruit such as palms, cinnamon and various Eugenia species," said Mr Lim.
The Little egret and Grey heron are two other birds that have flourished here due to Singapore's conservation policies. "They benefited from the Mandai mudflats and the expansion of the coastal reservoirs," he said.
Mr Lim said the society intends to continue the annual census.
He said: "We won't have 100 per cent coverage of the island, but if you do the surveys over a long period, it can tell you which species are going up, down or are maintaining their populations. If some of the birds seem to be having problems, you can also try to intervene to save them."
