The breeding pair were relocated from a colony in Scotland to Cropton Forest in the North York Moors back in April 2019, and the female gave birth to their first two offspring later that spring.
Forestry England, who manage the beaver reintroduction project, have now confirmed that a third kit has been born in a specially-constructed enclosure in the forest near Pickering.
Beavers remain with their parents for the first two years of their life, and next year conservationists will have to consider moving the elder two kits to another beaver project so that they can find mates once they reach maturity.
The family of five are monitored by 12 heat-sensitive cameras placed around their enclosure so that Forestry England ecologists can study their behaviour.
They have already observed the two elder kits helping to look after the newborn and teach it 'adult' tasks such as feeding and dam-building.
Forestry England ecologist Cath Bashforth said:
"The adult beavers settled in straight away after their release last year, quickly making the site their home. I am really pleased that they have had another kit this year and that all the whole family look so fit and well.
‘It is delightful to see the strong family bond on the footage from the trail cameras, with last year’s offspring helping with the new arrival. I look forward to watching the kit grow and learn from its siblings over the next few months. It will be fascinating to watch them work together as a family to further change the site with new dams and channels, reconnecting the river with its floodplain."
The aim of the five-year trial is to study the impact the animals have on the landscape and on natural flood management. Two former ornamental boating ponds inside their enclosure have filled with water again since the beavers repaired leaks to the banks, attracting other species, and they have also reconnected the beck in the forest with its floodplain.
There are several man-made dams and bunds in Cropton Forest built to prevent flooding downstream, and it is hoped that the beavers will 'adopt' and maintain these defences as well as building their own.
Back in February, The Yorkshire Post visited the beaver enclosure with Cath Bashforth - read more about it here.