KUALA LUMPUR, Malaysia >> Tens of thousands of birds cultivated for their edible nests are being banned from the capital of Malaysia’s tourist island after the U.N. cultural agency warned that the business endangers efforts to preserve decades-old buildings.

The bird breeders on northern Penang island voiced fears Thursday that the ban would disrupt the lucrative business that existed for years before UNESCO placed Georgetown on its list of World Heritage Sites in 2008.

A spot on the list helps attract tourists and U.N. grants but authorities have to follow restrictions to limit changes to the landscape. The restrictions pose a problem for entrepreneurs in Georgetown who convert old buildings into small farms where sparrow-like swiftlets live.