A startling 45% of executives are either actively seeking a new job or taking calls from headhunters. Can you spot who they are before they resign?

FORTUNE -- It never fails. After every recession, people (especially top performers) get restless, and their employers start fretting about how to keep them from jumping ship. This recovery, although it has come with a feebler job market than most, is no exception.

Not only are recruiters noticing that it's far easier to get A-list managers to take their calls than it was a year or two ago, but companies seem to be more intent on poaching each others' star players. Almost two out of three employers (63%) complained, in a survey last month by consultants Right Management, that competitors are aggressively wooing their best people. That's a marked increase from well under half (42%) who said so last year.

The big problem here, of course, is that the people you most want to keep may not come right out and tell you they're dissatisfied in their current jobs -- at least, not until they've accepted an offer somewhere else, and by then it's too late. So identifying who's eyeing the exits "is crucially important right now," notes Mark Anderson, president of ExecuNet, an online career network for senior managers. "We've found that the answers to four questions in particular will give you a pretty good idea of who's likely to leave."

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ExecuNet's researchers discovered those questions in the course of compiling the forthcoming 2013 edition of its Executive Job Market Intelligence Report, a detailed survey of 3,785 U.S. executives (average salary: $220,000) across a range of industries. Based on their answers to queries about their plans for the next 12 months, ExecuNet sorted the whole group into two categories -- the roughly 55% who plan to stay put, and the 45% who aren't so sure or are already plotting their departure.

In sifting through the data, the researchers noticed something interesting. "One of the questions we asked was, 'Are you proud of the company where you work now?'," Anderson says. "Among those who are planning to stay, 89% said yes, vs. 62% of those who are job hunting." Intrigued, ExecuNet started looking for other correlations and found three more:

• Do you enjoy your work? 86% of those Anderson calls "happy campers" said yes, vs. 58% of those planning to quit.
• Is your boss someone you respect and/or admire? 80% of loyalists answered yes, vs. 56% of job seekers.
• Would you refer other executives in your network for a job here? Among the happy campers, 75% said they would, vs. only 42% of the group looking to leave.

"Not recommending the company to others as a place to work, and not actively referring people for job openings, is a clear early warning sign that the person is disenchanted and is open to offers elsewhere," Anderson notes, adding, "We really think that the answers to all four questions could help employers identify where to focus their retention efforts."

How do you elicit honest answers? Anderson says top management has to sit down with the talent the company most wants to keep and start some in-depth conversations. He recommends asking, "Are you passionate about what you're doing? Or is there something else here that you'd rather be doing, or that you think we as a company should be doing but we're not?"

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The idea, Anderson says, is to "get at the heart of why this executive is here and how he or she sees the future. What could be going better than it is? How could his or her relationships with higher-ups and direct reports be stronger and more effective than they are now?"

Anderson acknowledges that there's no surefire way to tell who's going to quit, and a recruiter calling with an irresistibly juicy opportunity has been known to tempt even the most diehard loyalist. Even so, "open and direct discussions can go a long way toward getting insights" into how your star players see their current roles -- and what it would take to entice them to stick around.