Editor’s note: This story was originally reported in July 2015 and is being republished for its continued relevance.

Back in August 2013, two rare Sumatran tiger cubs—originally named Spot and Stripe—were born at Australia Zoo. Their birth was a huge moment for conservation efforts, as many cubs don’t survive in captivity.

Their early lives were featured in the 2014 BBC series Tigers About the House, which followed tiger expert Giles Clark as he became their hands-on caretaker, raising them almost like family.

With fewer than 350 Sumatran tigers left in the wild due to deforestation and poaching, the birth of these cubs offered a glimmer of hope for the critically endangered species. Now fully grown and renamed Hunter and Clarence, the brothers have become powerful adult tigers, symbolizing the importance of protecting wildlife for future generations.