Fewer piping plovers have returned to P.E.I. beaches this year. (CBC)

Piping plovers, birds already endangered in the Maritimes, could be in further trouble from the BP oil spill when they migrate south this winter.

While most of the birds spend the winter in eastern Florida, which is expected to escape the impact of the spill, some plovers could end up in areas affected by it.

"A few of them do cross over to the Gulf of Mexico, and it's very likely that those will be affected by this oil spill," said Jackie Waddell of P.E.I.'s Island Nature Trust.

"We've seen lots of video footage of oiled birds in terrible distress. And quite often we don't see most of those birds at all because they just die and they sink and you never see them again."

The population of birds on P.E.I. is particularly precarious. In the last few years, 85 to 100 birds have spent the summer on the Island, but this year the trust counted just 67. The plovers are particularly susceptible to oil along the beach.

Oil absorbed into feathers

"Plovers are shoreline feeders and they feed on sandy shores," said Waddell.

"We've seen lots of evidence of oil washing up on the sandy beaches in Louisiana and other states, and they'll be affected."

Kim Mawhinney of Canadian Wildlife Services said her group is working with U.S. Wildlife officials to keep track of Canada's migratory birds. She expects some plovers will run into trouble.

"The oil doesn't mix with the water but it's readily absorbed into the bird's feathers, and so when this happens, it decreases the bird's insulation from the cold, as well as their waterproofing and buoyancy. So this could lead to their death by hypothermia in cold waters."

There is little wildlife officials can do but watch, however, and Mawhinney said whether the birds will be affected will depend on where and when they fly south.