Two older African lions known for their devotion to one another were euthanized this week at the Los Angeles Zoo, which cited the pairs diminishing health.

Lions Hubert and Kalisa were both 21. The staff made the difficult decision to euthanize the pair because of their declining health and age-related illnesses that diminished their quality of life, the zoo said a statement .

This is a very hard loss for our Zoo community, curator of mammals Alisa Behar said in the statement. In the early mornings, staff would routinely hear Huberts waking roars, and I will personally miss hearing them on my walks around the ground. You cannot think of Hubert without thinking of his companion, Kalisa; theyve been an inseparable couple for years.