POLK CITY, Fla. -- Animal rights activists were stunned and pleased when the parent company of Ringling Bros. and Barnum & Bailey Circus announced it would eliminate elephants from its circus performances by 2018. But activists soon focused on the timing, questioning why it will take three years to phase out the elephants from the travelling circus shows.

"Many of the elephants are painfully arthritic, and many have tuberculosis, so their retirement day needs to come now," wrote Ingrid E. Newkirk, president of People for the Ethical Treatment of Animals, in a statement. "If the decision is serious, then the circus needs to do it NOW."

Executives at Feld Entertainment, Ringling's parent company, say it will take three years to build proper facilities for them on the 200-acre (80-hectare) plot of land in central Florida that's already being used as an elephant conservation centre. They have repeatedly denied that the elephants are mistreated in any way in the circuses.

"Each elephant requires a certain amount of space and a certain amount of barn area," said Stephen Payne, Feld's spokesman, adding that permits, drainage issues and other logistics must be worked out. The company intends for the elephants to live out their years on the property, and since one elephant is 69, they must plan for the long haul to care for the crop of gentle giants.

The decision to phase out elephants from the Ringling Bros. and Barnum & Bailey Circus comes at a time when cities across the United States are cracking down on exotic animal displays.

Even before Thursday's announcement that the elephants will be phased out of Ringling's performances by 2018, company officials already said they were pulling out of certain cities because of newly enacted restrictions.

Feld executives said the decision to end the circus's century-old tradition of showcasing elephants was difficult and debated at length. Elephants have often been featured on Ringling's posters over the decades.

Feld owns 43 elephants, 29 of which live at the company's 200-acre (80-hectare) Center for Elephant Conservation in central Florida. Thirteen animals will continue to tour with the circus before retiring to the centre by 2018.

Another reason for the decision, company President Kenneth Feld said, was that certain cities and counties have passed "anti-circus" and "anti-elephant" ordinances. The company's three shows visit 115 cities throughout the year, and Feld said it's expensive to fight legislation in each jurisdiction. It's also difficult to plan tours amid constantly changing regulations, he said.

"All of the resources used to fight these things can be put toward the elephants," Feld said during an interview at the conservation centre. "We're not reacting to our critics; we're creating the greatest resource for the preservation of the Asian elephant."

Carol Bradley, the author of the book "Last Chain on Billie: How One Extraordinary Elephant Escaped the Big Top," which is about a non-Ringling circus elephant, said she believes the Feld family "realized it was a losing PR battle."

"This is an enormous, earth-moving decision," she said. "When I heard the news, my jaw hit the floor. I never thought they'd change their minds about this."

In 2014, Feld Entertainment won $25.2 million in settlements from a number of animal-rights groups, including the Humane Society of the United States, ending a 14-year legal battle over allegations that Ringling circus employees mistreated elephants.

The initial lawsuit was filed in 2000 by a former Ringling barn helper who was later found to have been paid at least $190,000 by the animal-rights groups that helped bring the lawsuit. The judge called him "essentially a paid plaintiff" who lacked credibility and standing to sue. The judge rejected the abuse claims following a 2009 trial.

The circus will continue to use tigers, dogs and goats, and a Mongolian troupe of camel stunt riders joined its Circus Xtreme show this year. More motorsports, daredevils and feats of human physical capabilities will likely be showcased as well.

Ringling's popular Canada-based competitor, Cirque du Soleil, features human acts and doesn't use wild animals.

And while Ringling is phasing out the elephants, other, smaller circuses in the U.S. -- and in countries such as Russia, France and Thailand -- still use elephants.