In 2011, a Common Redshank was spotted in the Sungei Buloh Wetland Reserve but this was no random visitor.
The long, red-legged bird had been ringed in 1990 and had returned, showing it had survived more than two decades in the wild - possibly the longest on record for the East-Asian Australasian Flyway.
Such valuable information is only possible through bird ringing, which works in the same way as a dog tag except the rings are much smaller and lighter.
The ring or metal band placed around the leg of the bird gives it a unique serial number which tells researchers where it was first ringed and, in so doing, gives valuable insight into its ecology.
In the case of the Common Redshank, researchers were able to determine its lifespan in the wild.
And in order to better understand the birds that stop over in Singapore, the National Parks Board (NParks) will start tagging birds with satellite transmitters this year.
These can detect in real time their precise locations without their having to be recaptured.
"Bird ringing allows researchers to study and understand the migration patterns and lifespan of different bird species.
"Over the years, we have improved our methods of bird ringing so that more data is collected and with increased accuracy," said NParks director of conservation Wong Tuan Wah.
"The data collected is important in the protection and management of areas critical to the continual survival of these birds."
Efforts by NParks to ring the birds started in 1990 and, so far, more than 11,000 birds of 142 species have been tagged, About one in five of them (2,500) have been recaptured at least once.
"As these birds come back to the Sungei Buloh reserve repeatedly, it shows that it is an important refuge, and must continue to be protected and well managed," said Mr Wong.
The data collected has helped NParks to manage the wetland reserve by providing the right kind of habitats needed for birds to feed and roost.
For example, bunds (raised embankments) were modified as the two most common birds in the reserve - Whimbrels and Common Redshanks - prefer to stand on slightly higher ground than have their feet too deep in mud.
According to conservation group BirdLife International, which has six regional offices worldwide, many of the world's migratory species are in decline due to reasons such as habitat destruction, illegal hunting and climate change.
Singapore is on the East Asian-Australasian Flyway, which consists of various routes used by millions of birds to escape harsh winters up north. The flyway stretches from Arctic Russia and Alaska to Australia and New Zealand.
While habitat loss is one reason many of the world's migratory bird species are declining, Sungei Buloh has remained a safe haven for the thousands of birds that seek refuge there each year.
Last year, a higher number of uncommon species were also spotted at the reserve.
Mr Spike Millington, chief executive of the East Asian-Australasian Flyway Partnership, a voluntary initiative which aims to protect migratory waterbirds, their habitats and the livelihoods of people dependent on them, said tagging allows a better understanding of how birds adapt to changes in habitats, and how survival rates are affected by habitat loss.
"Migratory birds often rely on a network of "stepping stone" sites and habitats to complete their migratory journeys," said Mr Millington.
"What happens when critical sites are lost? Can birds adapt? Can they move elsewhere? Can young birds survive as well as more experienced adults?
"All of these questions can be answered, at least in part, by bird tagging," he said.
BirdLife International (Asia) and NParks are partners of the East Asian-Australasian Flyway Partnership for the conservation of migratory waterbirds and their habitats along the flyway.
Bird ringing efforts have slowly become more sophisticated over the years.
The simple metal bands used by NParks at the start gave way to green and white flags to show the birds had been tagged here.
The coloured flags enable researchers to see from afar where these birds have come from and better understand their migratory routes.
In 2014, tiny geo-locators which can detect light were used to record the location of the birds based on the timing of sunset and sunrise.
This can be used to calculate the longitude and latitude readings and, hence, the location of the birds.
The locators also record temperature, which shed light on the migration status and habitat conditions.
But things are about to get even better with transmitters.
Apart from the satellite transmitters that will be used for bigger birds, NParks will be tagging the smaller ones with radio transmitters about 1g in weight.
Efforts started last week with three Mongolian Plovers. The transmitters will help find out where else in Singapore these birds go other than Sungei Buloh.
The usefulness of such methods for bird tagging is maximised only if follow-up action is taken, said ecologist Yong Ding Li from the Australian National University in Canberra.
"In theory, if we know where a bird goes and spends substantial amounts of time, we can focus the conservation resources in protecting those places.
"For a number of bird species, scientists are still unsure where they migrate to, and thus it is difficult to plan for their effective conservation," said Mr Yong.
He cited the example of the Muraviovka nature reserve in east Siberia, which was identified as important to waterbirds, thanks to satellite tracking studies.
White-naped and Hooded cranes first caught and tagged in Izumi, Kyushu, in Japan, were later found to spend a lot of time in Muraviovka nature reserve. Some even bred there.
Eventually, this spurred conservation efforts to protect the Muraviovka area.
"Ultimately, how well science (and the study of bird migration by tagging) can help conservation efforts depends on local and national governments," said Mr Yong.