L.A. Zoo Elephants Billy, Tina Transferred to Tulsa Zoo Under Cover of Night

9:11 AM PT -- The L.A. Zoo has confirmed Billy and Tina the elephants have been "safely" transferred to the Tulsa Zoo despite fierce backlash over the move.

Contradictory to what critics argue, the zoo says in a statement Billy and Tina "will receive the same love and expert individualized care that they have had at the Los Angeles Zoo."

They also confirm Mayor Karen Bass inquired about having the elephants relocated to a sanctuary ... but after a "comprehensive evaluation" the decision to transfer the elephants to the Tulsa Zoo was "made with the health and well-being of the individual elephants as the top priority" -- plus a recommendation from the Association of Zoos and Aquariums and its Elephant Species Survival Plan.

Cher is gonna be pissed! The beloved L.A. Zoo elephants she went to bat for -- Billy and Tina -- were secreted outta the zoo under the cover of darkness last night ... TMZ has learned.

Sources connected to the L.A. Zoo tell us Billy and Tina were removed around 1:30 AM Tuesday and, presumably, loaded up to be shipped to Tulsa Zoo -- a controversial move that prompted protests, a lawsuit and an angry letter to L.A. Mayor Karen Bass ... which Cher and several other celebs signed.

We're told the elephant exhibit at L.A. Zoo was empty Tuesday morning -- no elephants, no keepers and the electric perimeter fence was off ... clear indications the animals were on their way to Oklahoma.

Our sources say the elephants were put into crates and loaded onto a semi-truck for the transfer to Tulsa Zoo. It's unclear how long the trip will take.

We reached out to several L.A. Zoo officials, but no one's called back, and L.A.'s Deputy Mayor -- who oversees the zoo -- hung up on us.

Advocates for Billy and Tina have been all over the L.A. Zoo for years, because Billy and Tina, Asian elephants, have been kept in an enclosure far too small for them.

Zoo officials say they'll have more room to roam in Tulsa, but as the letter to Mayor Bass said, "it is nearly impossible to humanely keep elephants in traditional zoos."