Moorhens in the Mariana Islands are found primarily at freshwater manmade and natural wetlands that are both seasonal and permanent. Occasionally, they are recorded in brackish water wetlands. In the Mariana Islands, moorhens have been recorded at golf course wetlands, commercial fish ponds, sewage treatment plants, wetlands created for the mitigation of wetland loss, but rarely at rivers and streams. Nests have been found in all months of the year. They are typically concealed in emergent vegetation near open water, but some nests are constructed out in the open on submergent vegetation beds or on floating debris.
Most active nests contain six eggs that are buff-colored with dark speckles.
Incubation lasts 19-21 days. Mariana Common Moorhens feed on a variety of plant and animal matter that may be located in the water, in and adjacent to wetland vegetation, and along the shoreline. They also fly between islands to utilize seasonal and permanent wetlands. Historically, the Mariana Common Moorhen was found on the islands of Guam, Tinian, Saipan, Rota, and Pagan. The Pagan population is believed extinct due to ash and cinder fallout from a 1981 eruption of Mount Pagan and overgrazing and rooting of emergent vegetation by feral cattle and pigs.