Declan Manley of Edenderry, County Offaly, has had his rings found on sand martens at two sites in Spain . . . in San Sebastian and in Malaga.

"I've been ringing on my own for six years now, " says Declan. "I got my comprehensive licence in 2000. I trained with a man called Hugh Brazier who was a very good teacher, very thorough."

Hugh Brazier, a British man who lived in Dublin at the time, used to travel down to Edenderry for the bird life, and now some of the people training under Declan Manley . . . two women and two men . . . do the same. The birds in county Offaly, says Declan, are undramatic but plentiful. He runs a tree nursery near the farm where he grew up.

The licences for bird ringing . . . a centuryold practice which allows migrating birds to be tracked . . . are issued by the Irish Wildlife Service and the British Trust for Ornithology (BTO). You must have a licence to net birds in this country. It is to the BTO that Declan sends the information which he enters in his beautifully tabulated notebooks. "Normally I send information every two months, " says Declan.

Declan has a tool box in his van, and in it is a CD player, run off a motor bike battery. The swallow song is on track 45, and it brings the birds to the nets. "My brother made it for me, " says Declan. He has had this passion since childhood. He jokes that he was born with a deficiency, but the rest of us would say that he was born with a talent.

"My father was quite aware of nature, " says Declan. "Years ago farmers were more in touch with nature. My father would say: 'The swallows are here, it's time to put down fertiliser.' Or he'd say 'There are lapwings flying over, there must be frost further up.' And then I had an aunt who was very interested in nature. When she came home from Birmingham she encouraged me to write everything down."

You haven't really seen a swallow until you have seen her carefully put in the pouch of a special scales. You haven't really seen a swallow until you have seen her weigh in at 19 grammes, and realised that this scrap of a thing is on her way to South Africa.

We found this swallow nesting in a barn. Declan Manley blew on her breast, and her feathers parted to reveal her bare breast bone underneath. This is her brooding patch, where she shed her breast feathers in order to keep her eggs in her nest warm against her bare skin. It was a David Attenborough moment . . . live.

Declan ringed her chicks as well.

Swallows' legs hardly grow any bigger as they mature, so the light rings which fit the adults do not have to be changed for the chicks.

We were in the barn because it was a wet day, and Declan's long mist nets hung empty. "You can't ring when it's wet, " said Declan. This is partly because the birds can spot the nets and avoid them. "Also if the birds hang upside down they get cold, " says Declan. "In winter if you're ringing you have to check the net every 20 minutes. Green finches in particular are prone to wing strain."

Last year Declan ringed 2,600 birds and this year he is up to 2,200 already. Half of those would be swallows and sand martens and half would be storm petrels.

In the summer Declan and his 15-year-old son, Patrick, were up two nights in a row, ringing petrels in Mayo. They breed on the stacks off Broadhaven. Stormy petrels take a harder ring . . . a ring which can withstand salt water. The ring for swallows is much softer, because they are so much smaller and they tuck their legs up under them.

For thousands of years bird migration was a mystery to humans. According to Oscar Merne of Birdwatch Ireland, our ancestors thought that swallows went to the moon in winter. Then people thought that they hibernated at the bottom of ponds. This makes perfect sense, says Declan, because swallows fly low over ponds and lakes as the summer comes to a close. They roost in reeds; although in modern times they have learned to roost in maize, which is like reeds. But all in all our ancestors get 10 out of 10 for observation, even if, as Oscar Merne says, they put two and two together and got five.

The young birds spend four or five weeks in the nest and then, as Declan puts it: "They fly around for a few months.

So they fly around Edenderry. Then they fly around Offaly. Then they fly around Leinster. Then they fly around Ireland. We think that they are mapping."

In the winter Declan rings garden birds.

He puts apples up for the fieldfares (large, colourful thrushes) and red wings from October on. Bird ringing has only been going on for one hundred years and bird ringers are more convinced than any of us that bird migration is still a mystery . . . if not a miracle.