A tiny trio of rare birds have sparked big celebrations on a Suffolk nature reserve – and they have marked a milestone in eastern England’s “comeback of the cranes” conservation success story.

The three crane chicks at the RSPB’s Lakenheath Fen reserve also represent the best “birthday” present the site’s staff and volunteers could have wished for as they have fledged in the reserve’s 20th anniversary year.

The past few months represent the best breeding season to date for the two pairs of cranes that nest at the site.

The parent cranes, which stand 5ft tall and have 8ft wingspans, have been resident on the reserve since 2007. One of the pairs made history in 2009 when they fledged the first young crane chick in the Fens for more than 400 years.

Since then, a further four chicks have fledged on the reserve. In 2012, both pairs fledged young in the same year for the first time ever.

Cranes breed in wetlands across northern Europe and Asia but have “amber” conservation status in the UK due to the small numbers breeding and wintering here.

Last year there were only 25 pairs of cranes nesting in the UK and the Fens population, which also includes birds nesting at RSPB Nene Washes, near Peterborough, forms a significant proportion of the British nesting population.

The RSPB has announced that one of the Lakenheath pairs fledged twins on July 6, with the second pair- known as Little and Large – fledging a single youngster on July 12.

As well as being the first season that three young have fledged on the reserve, it is also the first time that twins have fledged at the site.

Dave Rogers, the RSPB’s senior site manager for the reserve, said: “We put a lot of effort into managing the reserve for our cranes and it is fantastic that they have done such a good job of parenting this year.”