Thanks, further digging reveals that it's a Lindgren Funnel Trap.
As you point out, Emerald Ash Borer traps are supposed to be green or purple. So either the Canadian government got a deal on black ones or they are monitoring something else.
Given the local situation, EAB is still the most likely choice. These traps are placed just outside areas where there is a known infestation of some bark beetle. EAB has been found in Bolton but I don't think it has been confirmed in Palgrave yet, so Glen Haffy is a good place to monitor now. The Conservation Authority has been cutting down healthy ash trees near trails so it is definitely one of their top concerns.