After 145 years of featuring elephants in its circus acts, Ringling Bros. and Barnum & Bailey announced Thursday that it will retire its elephant herd by 2018.

"This decision was not easy, but it is in the best interest of our company, our elephants and our customers," said Kenneth Feld, chairman and CEO of Ringling Bros. and Barnum & Bailey's parent company, Feld Entertainment, in a press release.

The company said it made the "unprecedented" decision to focus its elephant work on conservation programs. "No other institution has done or is doing more to save this species from extinction," Feld said, "and that is something of which I and my family are extremely proud."

The circus will send its 13 traveling Asian elephants to the Ringling Bros. and Barnum & Bailey Center for Elephant Conservation in central Florida.

In an interview with the Associated Press, a Feld Entertainment executive vice president acknowledged a "mood shift" among the circus's consumers.

"A lot of people aren't comfortable with us touring with our elephants," said the executive, Alana Feld.

The company's press release said that "the circus will continue to feature other extraordinary animal performers, including tigers, lions, horses, dogs and camels."

Ringling Bros. Retired Its Elephants. This is Where They Live Now.

Intelligent—and Endangered

The Asian elephant (Elephas maximus) is the second largest land mammal on Earth, behind its cousin the African elephant.

Intelligent and strong, the Asian elephant is known for being a highly social animal capable of problem solving, grief, and empathy. (Related: "It's Time to Accept That Elephants, Like Us, Are Empathetic Beings.")

Habitat loss, conflict with humans, and the illegal wildlife trade drives the population a little lower each year. (Related: "100,000 Elephants Killed by Poachers in Just Three Years, Landmark Analysis Finds.")

A 2011 investigation by the magazine Mother Jones found that "Ringling elephants spend most of their long lives either in chains or on trains, under constant threat of the bullhook, or ankus—the menacing tool used to control elephants."

Despite abuse allegations raised by the Humane Society of the United States and other animal welfare groups, Ringling Bros. prevailed in a long legal battle against the groups in 2014, collecting nearly $16 million in a settlement.

People for the Ethical Treatment of Animals on Thursday called for the Ringling Bros. to expedite the elephants' retirement.

"Three years is too long for a mother elephant separated from her calf, too long for a baby elephant beaten with the sharp fireplace-poker-like weapons called bull hooks that Ringling handlers use routinely, too long for an animal who roams up to 30 miles a day in the wild to be kept in shackles," PETA president Ingrid E. Newkirk said in a statement.

RELATED VIDEO: Dr. Jim Laurita, co-founder and elephant manager at Hope Elephants in Maine, was tragically killed while caring for retired circus elephants on September 10, 2014.