Wetlands International, a global monitor of coastal areas and their wildlife, said the number of shore birds wintering in Malaysia had plunged by 22 percent over the past 20 years as the country aggressively developed its coastline for new housing, shrimp farms, industry and recreation.
The shrinking habitat means a loss of food and a break in the chain of wetland rest stops for migrating birds, the group said. "A larger number of young will starve. Slowly, the number born every year is declining," Wetlands spokesman Alex Kaat said.
Climate change also may be a factor. The report cited the construction of sea walls to protect against storm surges and rising sea levels as contributing to the changing coast line. Mud flats - ideal for wading birds - were being eroded or reclaimed for human use.
Kaat said the organization was careful about drawing a link to global warming, though he said other studies have blamed climate change for shifting migration patterns.
The destruction of mangrove forests heightened the threat to rare birds, Wetlands said. Traditional prawn ponds were being converted to deep pools for adding crabs. Hunters also have taken a toll on shore birds, the report said.
"The region is undergoing rapid economic development, but conservation policies are lagging behind," Kaat said.
The coast of Malaysia's peninsula is one of the most important wintering grounds for several endangered species, including the Nordmann's Greenshank and the Chinese egret, the report said.
Estimates by Birdlife International say the global population of the greenshank, which breeds on the coast of Siberia, may number fewer that 1,000. The Chinese egret also probably numbers no more than the low thousands.
Especially hit hard was the Perak coast, north of the capital Kuala Lumpur. A two-year survey ending in 2006 found an 86 percent decline from a similar survey in the 1980s. The Selangor area around the capital also showed dramatic losses of bird life, as did the wet coast of Johor, said the report.
Wetlands volunteers surveyed 134 sites in Malaysia. At the peak time, the survey recorded 105,000 water birds, with Selangor and Sarawak the most important sites.
Wetlands International is based in Wageningen, Netherlands.