Ms. Loh (LinkedIn)

Poaching for tech talent has reached such a crescendo in New York that, in some cases, proper etiquette is being thrown out the window. As Business Insider discovered with a few LinkedIn searches this morning, there seems to be a some kind of secret tunnel between Googleplex East and Foursquare. According to LinkedIn, 18 of Foursquare's 67-staffers hail from from Google.

Filching from the behemoths is fair game, of course, and restricted stock units and salaries at Google has risen to try to stop the tide. But that figure might be low-balling it. "A source close to the company said around a third of the company's employees have experienced some time at Google," reports BI.

That might have a little something to do with a trend Betabeat noticed last year.

Not only were Googlers getting poached, but Silicon Alley startups were also poaching Google recruiters. Last September, for example, Foursquare hired Susan Loh, a former lead technical recruiter at Google, away from Yelp to lead its efforts in New York. Then there's Morgan Missen, Foursquare's powerhouse recruiter out in San Francisco, who hails from both Twitter and Google. In June, Tumblr stole Sean McDermott away from Google's Chelsea outpost to help the startup increase its engineering staff. According to LinkedIn, there are at least four Tumblr employees who spent time at the GOOG, though we expect that number to rise.

He who poaches the poachers laughs last?