Some years ago, soon after my sister’s husband died after a long siege with severe Parkinson’s, she began getting phone calls from a seemingly kind and solicitous man. He had, according to my recollection of what she told me then, a deep, soothing voice, an impressive British accent, and a gift for listening and commiserating.

He, too, had lovingly cared for his spouse while she was dying of breast cancer, he told my sister; so he knew what she had just gone through in caring for her husband. In his daily phone calls to her, he tried to lift her spirits. He kindled dreams of travel to faraway places – in his private jet, of course. He sprinkled his conversation with British terms of endearment: “Yes, my love. … You’re so right, my love…” He posed as wealthy and worldly.

In giddy, school-girlish tones, my otherwise smart-cookie sister, who wasn’t born yesterday (for the record, she arrived in this world two summers after I did), told me about this prince of a guy and how happy he was making her at this low point in her life. She, like most of the rest of us, had a weakness for sweet talk, especially since it had been years since she’d heard any directed at her.

Longer story shortened: He began to press her for her banking and financial information, because, he said, he was a financial planner and he could help her make good investments now that her husband was gone. Red flags went up. She balked. He pressed on. She ended their brief “phonemance” and reported him. No long-term harm was done to her — other than to her pride.

Clever, charming predators live, operate, and thrive all over the world, alas. They are rife in Nature too; think: birds of prey. Even here in sunny, mellow Mexico, where I’ve found the vast majority of people to be honest and decent, good natured and kind hearted, I’ve crossed paths with one charming predator in particular, and no doubt there are many more out there. The challenge for us older, single, vulnerable women is to be smart and aware.

I was reminded of this lesson this week when a friend told me about her recent experience with a predator, who turned out to be the same one I’d known seven years ago when I was new to San Miguel. Youngish (in his forties then), darkly handsome, bilingual (he’d studied in the States), computer-savvy, and willing to assist with any technical problem (of which I had many at the time), he was the one I turned to for help, on someone’s recommendation. I spoke zero Spanish then. Admittedly, I was an old babe in these new-to-me woods.

I trusted him. Until I caught him in lies and theft. Two examples come to mind: selling me a second-hand smart phone for more than it was worth (telling me it was near-new, when it was really eight years old); charging me far more for a new laptop than it actually cost (after the one I’d brought with me to Mexico had been stolen).

Trust broken, I dropped him, went on my way, and tried to put this setback behind me. Now my friend here is in the process of doing the same with the same guy, only for her the stakes are higher. My heart aches for her. She is older than I, recovering from major surgery, and in fragile health.

Birds of prey, such as vultures, hawks, and eagles, are highly skilled at spotting smaller, vulnerable creatures at a distance and quickly swooping in to overpower them and whisk them away. Humans who prey on other, vulnerable humans show similar characteristics, I think.

One sure subset of vulnerable humans is older, single, women who live alone, have no family at hand, are in declining health, and seem to have means. Men who prey can spot them a mile away and are quick to swoop in.

In New York, I recall, I knew of a conniving businessman in his mid-sixties who romanced a wealthy ninety-four-year-old childless widow who lived on Park Avenue – no doubt with a view to becoming her sole beneficiary. I often wondered how he hid his talons from her. Or maybe her eyesight had dimmed by then.

Here in San Miguel de Allende, Mexico, where many older single women come to retire, at least partly because the cost of living is more affordable for us here, there is an added vulnerability when we don’t speak Spanish. We’re at a disadvantage, unless or until we make friends with a helpful local who will act as our interpreter or intermediary.

The goal, as ever, I believe, at this stage of life, is for us older women to become wise. Not bitter or frightened or overly wary of others, but wise. Trust is essential in human relations, but trust must be tempered by reality: Not all birds are benign. And, too, trust must be earned.