For decades, Canada's tufted puffins have failed to reproduce chicks. Now scientists think warmer ocean temperatures may be to blame.

Triangle Island off the north coast of Vancouver Island is the only place in Canada where the seabirds are found in significant numbers – an estimated 50,000 pairs.

Tufted puffin (Courtesy: University of
Researchers at Simon Fraser University, the University of Alberta and Environment Canada have been tracking reproductive changes in the puffins since 1975.

They've found a direct relationship between the puffins' breeding success and temperatures.

Records at Pine Island Light Station in British Columbia show a warming trend of 0.9 C from 1937 to 2002. Eight of the 10 warmest years occurred between 1990 and 1998.

The birds raised few chicks when sea surface temperatures were unusually cold during the 1970s, or especially warm, such as the 1990s, according to behavioral ecologist Colleen Cassady St. Clair of the University of Alberta.

The team speculate the puffins' prey are behind the change. Tufted puffins eat small fish and an anchovy-like species called sand lace.

St. Clair said when the breeding colonies are surrounded by warm water, the puffins can't catch fish. The adults appear to abandon their chicks, perhaps so that they can forage farther offshore and the chicks are left to starve.

"Projected further increases in global temperature and a lack of any (land)…otherwise suitable for puffin colonization may dramatically reduce numbers on Triangle Island, the stronghold of the species in Canada, within a few decades," the researchers wrote in this week's issue of the journal, Proceedings of the National Academy of Sciences .

They suggest puffins may act as a valuable indicator for the marine ecosystem in the Pacific region.