The birth of wildcat kittens in the Cairngorms national park has been hailed as a “major milestone” in efforts to rescue the secretive mammals from extinction in the UK.

In footage exclusively shared with the Guardian by the Royal Zoological Society of Scotland (RZSS), two of the kittens can be seen playing in grassland with their mother and leaping on to a fallen tree branch.

These are potentially the first wildcats to be born outside captivity in Scotland for more than five years after 19 wildcats, which had been bred at the Highland wildlife park, near Kingussie, were released last summer in sites across the Cairngorms in a pilot project by the Saving Wildcats partnership, led by RZSS.