The existing wooden bunkhouse dates from about 1914. After this building floated thirty feet downstream during the El Niño flood of 1997, an archeological test pit was excavated near the original northeast corner of the foundation. This test revealed a low masonry wall with thick lime plaster and a very solid, highly polished concrete floor. This floor is about eighteen inches below the present ground surface. Review of the existing island records or literature did not reveal any mention of an earlier building.

However, three maps, dated 1876, 1885, and 1892, show a square structure in what appeared to be the same location. On the later two of these maps, this structure is labeled as a residence. None of the maps has a scale, but the 1892 map shows the existing two-story adobe building, which is slightly longer than 50 feet. If the buildings are accurately shown to scale on this map, this older residence was 31 feet square. No other details of the structure were depicted on the map.

This building was likely the oldest ranch residence on the eastern end of the island. Archeological evidence indicates that it was constructed of adobe.