As investigators continue to probe the deaths of about 7,500 songbirds at a Saint John gas plant over the weekend, some birders are worried about other possible deaths.

Jim Wilson says the migrating season is far from over and hopes future deaths can be prevented.

"A lot of our other birds will be migrating throughout September, and on through October, and even into November," he said.

"So the hazard isn't just a one night thing. It's, you know, continuous throughout the migratory season."

Red-eyed vireo

A large number of red-eyed vireos were among the estimated 7,500 migrating songbirds killed by the flare at Canaport LNG. (Courtesy of the Migration Research Foundation)

An estimated 7,500 migrating songbirds, possibly including some endangered species, were killed while flying over Canaport LNG between Friday night and Saturday morning.

It appears the birds flew into the gas flare, which towers 30 metres above the liquefied natural gas receiving and regasification terminal, officials have said.

About 6,800 of the birds were killed, while several hundred more were injured and had to be put down.

The Canadian Wildlife Service and the Atlantic Wildlife Institute are trying to determine the cause and will make recommendations to avoid a similar incident.

Wilson says he has never heard of anything like it happening before on such a massive scale.

'Like moths to a flame'

But he says the birds being attracted to the flame isn't a surprise.

"There are many early accounts of lighthouse keepers seeing birds all around the lighthouse, just thick as flies on a misty night, on an overcast night," he said.

"So…no one knows quite why they're attracted at night, but it's like moths to a flame, literally, or to a candle."

Many birds migrate at night, using the stars and the moon to navigate, which would have been difficult on the night in question due to fog and low cloud cover, said Wilson.

"When you get low cloud, when you get mist, rain, light rain, that kind of thing, sometimes their normal navigational cues are affected a little bit and they don't fly as high as they normally would."

Don McAlpine, the head of zoology at the New Brunswick Museum, is still examining several hundred of the dead birds to try to identify their species.

There were a large number of red-eyed vireos, several types of warblers, including parula, black-and-white, magnolias and redstarts, as well as a few thrushes and rose-breasted grosbeaks, he said.

It's possible there may have also been some endangered species, such as the olive-sided flycatcher and Canada warbler, which are on the federal government's species at risk registry, said McAlpine.

Several of the birds have also been sent to the Atlantic Veterinary College in Prince Edward Island for necropsies to determine if there were any underlying conditions or external factors that may have contributed to the bird deaths.