Mimi is an old girl — the grand dame of the Denver Zoo, where she has ruled the roost since 1961 in spite of her shyness.

She is at least 53, and elephants, under human care and in the wild, have an average life span of just over 44 years.

Mimi’s slow decline has been steeper lately and harder to watch. Tender feet, sore joints and a slower gait have been apparent for a while — but when their “big-boned” girl recently lost her legendary appetite, zookeepers started thinking about the end.

“She’s quite the chowhound, and seeing her not want to eat is new and concerning,” said large-mammal curator Dale Leeds of his pachyderm friend of two decades.

Staffers have started anxiously monitoring what she’s eating instead of watching in awe as it disappears.

“What we realized the other day is that we really need to put her in hospice care,” said Denver Zoo president and chief executive Craig Piper. “What that means for her is that she tells us what she wants to do, where she wants to go. Inside? Fine. Outside? Great.”

It doesn’t mean zookeepers have given up on her. She could rebound. She had a pretty good day Thursday, they said.

It doesn’t mean veterinarians have stopped treating her and trying all the latest therapies to make her feel better and stronger, Leeds said.

It is time, though, for the community to prepare to say goodbye.

“Mimi is one of the most beloved animals in the zoo,” Piper said. “We want everyone in Denver to understand how precious she is.”

Mimi has entertained tiny kids who now sit on the zoo’s board of directors.

“She’s seen it all,” Leeds said. “She’s been here longer than about anybody.”

Mimi always enjoyed any food put in front if her, but the sweeter the better. She now gets all the favorites — bagels and melons — that she wants, within reason, to help coax her to eat. If she wants to hang out with her old friend, Dolly, she does. Or she can choose to be on her own. She gets medications to make her more comfortable.

“All the staff is looking for a little extra Mimi time, some quiet time with her,” Piper said, “but if they sense she wants alone time, she gets it.”

She has been a little less social with her humans. Mimi would follow them around when she was in one of her “schmoozy moods,” as they called them. She could be very affectionate. She’d want to be rubbed. She liked her tongue rubbed. It’s an elephant thing.

Mimi also has her own particular quirks, including a bird phobia — she’s very nervous around geese.

She was never a big lover of “object manipulation,” also known as playing with toys, but she did have a thing for pounding large suspended objects.

When Mimi and Dolly moved into their posh new exhibit, Toyota Elephant Passage, in December, zookeepers wondered whether Mimi would take to it.

“Change could be a little bit tough for her,” Leeds said. “She can be suspicious. I thought it would take more time for her to adapt to it. To my surprise, she adapted to it really quickly.”

To the delight of staff members she became an explorer, and they’ve loved telling stories about her latest adventures that began with: “You won’t believe what Mimi did today …”

“One of the things I’m happiest about is that she got some time to enjoy the new home,” Piper said.

Leeds said he has loved spending Christmases with Mimi — when it was quiet at the zoo, with just the immediate family around.

If this is the end of Mimi’s life, Piper said, zookeepers want it marked by respect and dignity.

It’s too soon, though, to talk about services, ultimate dispositions and farewells. Everyone is still hoping for a rally.

“We are always looking for ways to make her feel better,” Leeds said.

Electa Draper: 303-954-1276, edraper@denverpost.com or twitter.com/electadraper