The plaque reads:
The memorial sponsored by the Langdon Club is dedicated to 'Martha' September 1, 1914, the last passenger pigeon and 'Inca' February 21, 1918 the last known Carolina Parakeet and all extinct species. This building was home to Martha and Inca for many years until their deaths. It is the hope of the Langdon Club that people who visit this memorial will work toward the preservation of all the world's fauna.
A National Historic Landmark Building originally being one of seven aviaries that is dedicated to the last living passenger pigeon, Martha, and the last Carolina parakeet, Inca.
