When do those birds expire?

A new US government website, PlainLanguage.gov, provides examples of re-writing to eliminate ambiguities, including this one:

Before

This rule proposes the Spring/Summer subsistence harvest regulations in Alaska for migratory birds that expire on August 31, 2003.

After

This rule proposes the Spring/Summer subsistence harvest regulations for migratory birds in Alaska. The regulations will expire on August 31, 2003.