It's a mystery with enormous consequences for the survival of a species: where do piping plovers from eastern Canada go when they head south for the winter?

Shannon Mader, species at risk co-ordinator with P.E.I.'s Island Nature Trust, said despite the efforts to protect them on their northern breeding grounds, "we're still not seeing a recovery."

"So we do believe that something is happening during migration or over winter."

A study by Environment Canada that began in 2013, which included putting tiny bands on the plovers, has started to turn up clues as to where the plovers go.

This plover named T5 was banded at East Lake, P.E.I., in 2014 and has been seen in the Bahamas and southern Nova Scotia but not on Prince Edward Island. (Submitted by Nazo Gabrielian)

P.E.I. plovers have been spotted this winter in the Bahamas, the southern states of Georgia, Florida, North and South Carolina as well as, for the first time, Bermuda.

They're tough little dudes, I'm in awe of what they do. — Shannon Mader

"It's so nice to hear, you can picture them down there on the beach with the palm trees," Mader said.

"They're tough little dudes, I'm in awe of what they do, the conditions they face to make this trek from year to year."

Shannon Mader of the Island Nature Trust says every bird, every nest is critical to find and protect. She's seen here on Barachois Beach, P.E.I. (Submitted by Sean Landsman)

But some may not be making it back. The number of plovers in eastern Canada is declining — a 37 per cent drop over the last 10 years — said Jen Rock, wildlife biologist with the Canadian Wildlife Service in Sackville N.B.

She has travelled to the Caribbean multiple times — including visits to the Bahamas, Cuba and an upcoming trip to the Turks and Caicos — to look for the Canadian plovers.

Jen Rock frequently travels to Caribbean countries in search of plovers. (Submitted by Jen Rock)

"It does look like part of what is contributing to that is survival during the non-breeding season so we're really interested in where birds are migrating through and also where they're spending their winters," she said.

The biologists and volunteers scour the beaches and flats looking for habitat where we think the birds may be.

"It's pretty tricky, it's different from up here at home where they're nesting," Rock said.

"They can be in larger groups but you come across a few at a time also and they're very well camouflaged."

This piping plover banded on P.E.I. was sighted in Bermuda. (Submitted by Andrew Dobson)

When a plover is spotted, it's cause for celebration.

"It's really exciting and it's important too because every detection of a different individual is feeding into the bigger picture so it's a piece of the puzzle in terms of trying to understand where these birds are wintering."

This P.E.I. piping plover, named 0H, was photographed in South Carolina. (Submitted by Melissa Chaplin)

On P.E.I., there is a guardian program to protect the piping plovers and their habitat. Rock would like to see similar efforts in the Caribbean.

"Some groups are working towards initiating very similar sort of guardian programs down south, for example, in the Bahamas, but certainly it's absent across most of the Caribbean," she said.

"Anything to protect these birds would make a difference and would potentially help the population."

A large concentration of shorebirds, including piping plovers, were discovered on Joulter Cays in the Bahamas in the 2011 census. The site is now protected as a national park. (Submitted by Jen Rock)

With just 60 plovers counted on P.E.I. in 2017, Mader said every single bird and every nest is critical.

"I think we here on the breeding grounds tend to think of them as our birds, these are P.E.I. piping plovers, but they spend more than half the year somewhere else," Mader said.

"We can put all of this effort in here on the breeding grounds but if there's no protection on the wintering grounds then they're incredibly fragile."