Bizarre.
Found this with some more references if you haven’t seen it...
1974: BLACK HELICOPTERS OVER ONTARIOhttp://www.ufoinfo.com/roundup/v10/rnd1013.shtml[emphais mine]
"There were two sightings of a UFO in early January (1974) near Snow Road Station, Ontario. One witness, whose account was filed with the Meteor Centre, described it as looking like the bottom portion of a hovercraft with two rotors on the top. And the other witness I located feels convinced it was a helicopter travelling away from her as she couldn't see the tail of it...Both witnesses stated that the craft was moving eastward."
These sightings soon drew the attention of local newspapers, in particular, the Lindsay Post. "Later, in early March (1974), a series of sightings of a weird aerial artifact occurred near the Lake Boshkung area. They were said to have four large wings with an overall wingspan of 20 feet (6 meters), dark in colour, and with lights that appear to change colour."
"'They were monstrous planes, black in colour and shaped like a pollywog,' according to" one witness, Ms. Lunham, who "said that they were noiseless, with one exception--when one of them appeared to have some difficulty taking off and gave off a thump-thump noise. It is her belief that they are not from outer space but (are) some experimental craft being tested by the U.S. and Canadian military."
"And in her concern, she has written to the (Canadian) Minister of National Defence without receiving a response."
"An effort to photograph the lights was made by (reporter) Peter Courtney of the Minden Progress, but the lights were too dull and moved too fast for any good photographs."
"One description of the UFO was that: 'It looked like a helicopter with the tail off.' Markings of a landing behind the Lunham residence made several weeks earlier were examined; and though they were fairly old, they were made up of a V-shaped marking with two pad-like markings at right angles to it."
"Two further sightings were made by a Jerry Gavreau, to the south of Lindsay. 'The first...was made when he noticed that what he had first taken to be helicopters were 'tail-less' while watching them through binoculars; and the second was made near Orono when a cigar-shaped object passed before him at low level."
Maybe a stretch but a quick search turned up this...

Canadair CL-84 "Dynavert"http://en.wikipedia.org/wiki/Canadair_CL-84The Canadair CL-84 was a V/STOL turbine tilt-wing monoplane designed and manufactured by Canadair between 1964 and 1972. Only four of these experimental aircraft were built with three entering flight testing. Two of the CL-84s crashed due to mechanical failures, but no loss of life occurred as a result of these accidents. Despite the fact that the CL-84 was very successful in the experimental and operational trials carried out between 1972 and 1974, no production contracts resulted.
I wonder if there are any bases or airports nearby? If not, that might be one way to rule that out…
Men go and come but Earth abides.