Two small, very attractive birds, with black "masks" across their eyes and russet backs, perching on fence posts, barbed wire and branches, flicking their wings and tails before dashing off after passing beetles and bumblebees: that's what hope looks like.

Nobody thought they would come back. Just five years ago, the best and most comprehensive book on English birds said the species was "unlikely to breed here on a regular basis again". Yet there they were on the edge of a small valley in Dartmoor, two juveniles fresh from their Dartmoor nest and feeding up for their long migratory journey to winter in southern Africa: red-backed shrikes.

The announcement yesterday that Lanius collurio had bred again in Britain, 18 years after going extinct, delighted conservationists and birdwatchers. This is (or was) one of the most engaging of all our birds, an exquisite small predator, something like a falcon the size of a sparrow – a sparrow with a hooked beak and a ferocious intent.

Its fierce behaviour long ago gave it a country name, the butcher bird, for the red-backed shrike catches its prey items – beetles, caterpillars, lizards, small mammals and even other small birds – and then stores them in "larders" by impaling them on the spikes of a thorn bush or a barbed wire fence. The butcher bird was a part of rural folklore right across Britain, until a decline began in the middle of the 20th-century which accelerated through the 1970s and 1980s, with the last pair breeding in Norfolk in 1992.

It was widely assumed they were gone forever. Leading ornithologists Andy Brown and Phil Grice wrote in their authoritative Birds in England in 2005: "The prospects for any recolonisation look bleak."

But on Wednesday The Independent was invited to view the birds which have returned, at the secret breeding site where they have spent the summer, guarded 24 hours a day, seven days a week, in an operation involving several conservation organisations and coordinated by the Royal Society for the Protection of Birds.

The adult male, resplendent in his grey-blue head which contrasts with his red-brown back and black face mask, appeared to have gone, to have left for winter quarters in sub-Saharan Africa; the adult female was also nowhere to be seen. But two of the three young birds they successfully raised were splendidly on view in the isolated scrubby valley with a small stream that has been their home, and to which – the hope is – they will return next year to breed themselves.

The birds were surveying their world from hunting lookout posts and then fluttering and swooping down on prey, with big black beetles being a favourite item: these were taken back to the perches and greedily torn apart, as the birds built up their fat and muscle reserves for the 5,000-mile flight which awaits them.

Watching them with Peter Exley and Kevin Rylands from the RSPB and Roger Smaldon from the Dartmoor Study Group was not only an intense pleasure in itself; it was to witness a triumph of active conservation. For perhaps more than any other British bird, the red-backed shrike has suffered at the hands of egg collectors.

Colourful and also highly variable, the eggs have always been prized by "eggers" and as the bird became rarer, so did their value to collectors; the fewer breeding shrikes there were in the 1980s, the harder the eggers tried to get them, often succeeding. Although the full reasons for the birds' disappearance are not known – one may be the disappearance of large insects from the countryside – it is almost certain that egg collectors had a hand in driving them to extinction.

Any returning birds would be targeted, of course – despite penalties which now include jail sentences, there are still enough egg collectors to drive the birds to extinction once again – and as soon as it was realised that a pair were present and nest-building, in late May, a protection operation began.

It involved RSPB staff and volunteers from the Dartmoor Study Group and the Devon Bird Watching & Preservation Society, who spent more than 2,600 hours constantly overlooking the nest. They were needed. Three men with criminal convictions for egg collecting approached the site, before being warned off; another man was discovered in hiding, trying to spot the nest (he fled through a peat bog when challenged, up to his knees in mud).

That the chicks eventually hatched, and safely fledged, was a major achievement for the volunteers. But perhaps it was an even greater achievement for the parent birds themselves, for they lost their first brood of chicks to marauding magpies in July, yet stoically started out again. "I saw them mate again, and begin nest building once more, on the same day," Mr Rylands said.

They need to be stoic in this world where the threats to so much of our wildlife continue, with farmland bird numbers, for example, down by 50 per cent in the last four decades, and still falling. Yet watching the young shrikes on Dartmoor, these brilliant birds that have come back from the dead in our country, there was an overwhelming sense of the resilience of living things, given half a chance, and a feeling that for all the threats, there is hope for our wildlife too.

A summer to remember

The breeding of the red-backed shrikes on Dartmoor crowns what has been a remarkable summer for rare and new breeding bird species in Britain, especially for long-legged water birds.

* Purple herons, more colourful but much shyer cousins of our own grey herons, bred successfully for the first time ever in Britain at the RSPB reserve in Dungeness in Kent. (They had tried and failed at Minsmere in Suffolk in 2007). The Dungeness birds have raised two chicks.

* Little bitterns, small members of the heron family, bred in Somerset, for only the second recorded time in Britain (the first occasion was in Yorkshire in 1984). These elusive birds nested at Ham Wall nature reserve and raised at least one chick.