you do not appreciate some things until they go away or become extinct Now we have only memories of of our song birds. You don't miss the water till the well runs dry.
YOU DON'T MISS THE WATER TILL THE WELL RUNS DRY
Meaning of YOU DON'T MISS THE WATER TILL THE WELL RUNS DRY in English
English idioms vocab. Словарь английских идиом и выражений. 2012