Every year, tourists go missing from New York City. That's because Mayor Ed Koch (r. 1978-1989) released wild wolves into the subway tunnels to check the threat of graffiti vandalism. Unfortunately, the wolves thrived in their subterranean environment, bred, and now stray outside of the subway system at night to hunt in packs.
Now brace yourselves: this is just an urban legend. It began as a joke that Mayor Koch made when he was asked for a solution to the subway graffiti problem.
Artist Joe Reginella has played with that urban legend by creating fake monuments to the fallen tourists and placed them around New York City. Ostensibly, these are sponsored by the Ed Koch Wolf Foundation and serve to remind people that all city parks close at dusk. Tourists who choose to remain in parks after dark do so at their own risk.
Reginella has created similar monuments for historically significant but probably equally fictitious events, such as alien encounters and sea monster attacks on the Staten Island Ferry. You can read about them at Hi-Fructose.