A colleague appeared. “Wow,” he said, leading me to a display case. “We do have snakeskin bags back here. Is he nice? Does he bite?” The salesman handed me a smart, yellow python bag marked $9,000. “I think this would work the best. It’s one of our classics. I think yellow. Red makes the snake look too dull.”

The welcome wasn’t as warm at Mercer Kitchen, where a maître d’ responded to my request for a table by saying, “Not with that!”

“But it’s a companion animal,” I said. “It’s against the law not to let me in.”

“I understand,” he said. “But I need you to take that out.”

Over at Balthazar, once the woman at the front desk confirmed with her superior that snakes could count as emotional-support animals, I was able to make a lunch reservation for the following week. (“So that’s how you get a table there,” a friend said.) An hour later, I learned that the Angelika Film Center does not require you to purchase a separate ticket for your snake, and that the Nespresso coffee bar is much too cold for an ectotherm.

To think that animals were once merely our dinner, or what we wore to dinner! Fifteen thousand years ago, certain wolves became domesticated and evolved into dogs. One thing led to another, and, notwithstanding some moments in history that dogs and cats would probably not want to bring up (like the time Pope Gregory IX declared cats to be the Devil incarnate), pets have gradually become cherished members of our families. According to “Citizen Canine,” a book by David Grimm, sixty-seven per cent of households in America have a cat or a dog (compared with forty-three per cent who have children), and eighty-three per cent of pet owners refer to themselves as their animal’s “mom” or “dad.” Seventy per cent celebrate the pet’s birthday. Animals are our best friends, our children, and our therapists.

“I hate all of these people,” Jerry Saltz, the art critic for New York, told me, referring to pet owners “who can’t be alone without their dogs or who feel guilty about leaving their dumb dogs home alone.” He went on, “A few years ago, my wife and I were flabbergasted to see a smug-looking guy sauntering through MOMA while his ‘comfort dog’ happily sniffed the paintings, as if to pee on one. I ran up to a guard and started yelling, ‘That guy’s dog is about to pee on the Pollock!’ She looked at me and said, ‘There’s nothing we can do about it.’ ”

Why did the turkey cross the road? To get to the Hampton Jitney. How did the twenty-six-pound fowl get across? With me hoisting him by his “Emotional Support Animal” harness, as if he were a duffel bag.

“You’re taking this with you?” an attendant asked, standing in front of the luxury bus on Eighty-sixth Street. Henry was a Royal Palm, a breed not known for its tastiness but one that could easily make the cover of People’s sexiest-poultry issue. His plumage is primarily white, but many of the feathers are accented with a tip of jet black, giving him a Franz Kline Abstract Expressionist feel.

“Yes,” I said, handing the man two tickets, one for me and one for Hope, the turkey’s ten-year-old neighbor, in Orange County, New York. Henry flapped his wings furiously, dispersing a good amount of down into the air and emitting noises not unlike the electronic beeps that a car makes when it’s too close to the curb. Henry had been driven in from the farm that morning.

“Did you talk to the company?” the attendant asked.

“Yes,” I fibbed.

“Good boy, good boy,” Hope whispered to the heaving bird, as I strained to lift him up the bus’s stairs.

“He’s my therapy animal,” I primly told the driver. “Do you want to see the letter from my therapist?” The question was not acknowledged.

“Easy, buddy,” Hope said, helping me to park Henry on a seat next to the window. Soon the bus was lurching down Lexington Avenue. The turkey angrily flapped his wings. I hovered in the aisle, because, truth be told, I was a bit emotional around my emotional-support animal.

“If you sit with him, maybe he’ll calm down, right?” the attendant said. I slid in next to Henry, whose eyes seemed fixed on the Chase bank sign out the window.

“Did you take him for immunizations and everything?” the optimistic attendant asked. Simultaneously, I said yes and Hope said no.

“How much food does he eat?” the attendant continued. “Like, half a pound?” A huddle of passengers had gathered in the aisle, and a lot of phone pictures were snapped. The Jitney stopped at Fifty-ninth Street to let on more passengers.

“Is that a real turkey?” a woman said to her friend as she passed Henry. (No matter what the animal du jour, someone always asked me whether it was real.)

At Fortieth Street, Henry and I, who had pressing appointments in Manhattan, disembarked (“Oh, no. I think I forgot something,” I said. “I have to get off”), leaving a trail of plumage behind. The attendant, who asked for a picture of himself with the turkey, was more perplexed by our getting off (“You’re going to pay thirty dollars to get off at Fortieth Street!”) than by our getting on.

Next stop: Katz’s Delicatessen, at the corner of Ludlow and East Houston Streets. “How many?” the guy at the front desk asked, after I’d shown him the therapist’s letter and we were joined by two of Henry’s human friends.

“Four, plus the turkey,” Hope said. We followed a waiter through the crowd until Henry, whom I’d been leading on a leash, plopped onto the floor in a spot that blocked traffic. Hope and I dragged him to a table and hoisted him onto a chair, on which he lay immobile, on his side with his feet splayed as if he’d conked out on the sofa, watching TV. A wing drooped over one side of the chair.

“What kind of emotional support do you get from him?” a man asked. Henry’s E.S.A. badge had come off earlier, when he jumped onto a dumpster on East Houston Street (“He needs to roost,” Hope’s mom said), but the news of his presence had spread among the diners as if he were Jack Nicholson.

Depending on his mood, a turkey’s head and neck can be red, white, blue, or, if very excited, some combination of the three. After lunch, Henry’s head had turned purple. His handlers decided that he was “too stressed” and ought to be getting back to the farm.

“Too stressed for yoga?” I said, having hoped to take the turkey to a class at Jivamukti. Did my emotional-support animal need a support animal?

Reflecting on whether it is reasonable to be this inclusive of man’s best friends, I called the Australian philosopher and ethicist Peter Singer, who is best known for his book “Animal Liberation,” which makes a utilitarian argument for respecting the welfare and minimizing the suffering of all sentient beings. Singer takes a dim view of the emotional-support-animal craze. “Animals can get as depressed as people do,” he said, so “there is sometimes an issue about how well people with mental illnesses can look after their animals.” He went on, “If it’s really so difficult for you to be without your animal, maybe you don’t need to go to that restaurant or to the Frick Museum. ”

An alpaca looks so much like a big stuffed animal that if you walked around F.A.O. Schwarz with one nobody would notice. What if you tried to buy a ticket for one on an Amtrak train? The alpaca in question was four and a half feet tall, weighed a hundred and five pounds, and had a Don King haircut. My mission: to take her on a train trip from Hudson, New York, to Niagara Falls.

“Ma’am, you can’t take that,” a ticket agent at the Hudson station drawled, in the casual manner in which you might say, “No flip-flops on the tennis court.”

“It’s a therapy animal. I have a letter.”

“O.K.,” she said flatly. “That’s a first.” I paid for our tickets. On the platform, the alpaca, whose name was Sorpresa, started making a series of plaintive braying noises that sounded like a sad party horn. Alpaca aficionados call this type of vocalization humming, and say that it can communicate curiosity, concern, boredom, fear, or contentment but is usually a sign of distress. Sorpresa’s wranglers, who raise alpacas for wool, and who had accompanied us, decided that she’d be better off staying closer to home. They had no problem, though, with her accompanying me to CVS and to some art galleries along Hudson’s Warren Street (man in gallery: “Wow! Are they the ones that spit?”). In fact, alpacas rarely spit at humans.

At Olana, a New York State Historic Site, showcasing the nineteenth-century home of the painter Frederic Edwin Church, Sorpresa and I were stopped at the visitors’ center by an apologetic tour guide. A higher-up named Paul was summoned, and kindly broke it to me that animals were not permitted.

“It’s a museum and a historic home,” he said. “There are thousands of distinct objects in there that are over a hundred and twenty years old. I’m sorry, but we just have never been able to take that risk.”

While the alpaca stood, perfectly behaved, in the gift shop among hand-painted porcelain tiles, glass vases, and antique lanterns, and I fielded questions from shoppers (“Are you allergic to dogs?”), Paul consulted the site manager in charge of Olana. They called their boss in Albany to ask for guidance.

When you hear that the livestock in your custody has been granted permission to clomp through the premises of a national treasure that houses hundreds of priceless antiques, you do not feel unequivocal joy—particularly when the beast has been known to kick backward if a threat from the rear is perceived. Don’t ask me anything about Frederic Church’s home. Could you really expect me to concentrate on the art when all I kept thinking was: “Didn’t the owners say that when the alpaca’s tail is held aloft it means she has to go to the bathroom?” By the time we reached Church’s entertainment room, Sorpresa was intently humming a distress signal.