Tinian Island

Country/territory: Northern Mariana Islands (to USA)

IBA Criteria met: A1, A2 (2007)
For more information about IBA criteria please click here

Area: 9,888 ha

Most recent IBA monitoring assessment
Year of assessment Threat score (pressure) Condition score (state) Action score (response)
2012 high unfavourable negligible
For more information about IBA monitoring please click here

Site description
The proposed Tinian Island IBA encompasses the majority of the island, excluding a small settlement in the southern part of the island and including a large military leasehold area in the north. Part of the military leasehold area is designated a National Historical Site. The military leasehold areas are used for training exercises, but are uninhabited. The proposed IBA includes the Hagoi Marsh and Marpo Swamp areas, which are important as water sources and as animal habitat.

Key biodiversity
Engbring et al. (1986) reported that the Tinian Monarch, endemic only to Tinian, was present in every surveyed habitat in Tinian. The USFWS (2005) also found that the Tinian Monarch inhabited a variety of forest habitats, including native, secondary, and introduced vegetation. Engbring et al. (1986) also found that other native birds were distributed throughout the island. Engbring et al. (1986) found that the northern part of Tinian, the location of Hagoi marsh, held the largest population of monarchs and was important for wetland birds, including the US federally listed and protected Mariana Common Moorhen. Tanaka and Haig (2004) found that Mariana Common Moorhens appear to use Tinian’s Lake Hagoi, particularly during the dry season. Wiles et al. (1985) and O’Daniel and Krueger (1999) found the Micronesian Megapode on Tinian. O’Daniel and Krueger (1999) reported sightings of the Megapode were made at Maga, Upper Mt. Lasu, and Bateha, all sites with native limestone forest. These sites are located on the center escarpment of the island. Native forest is also found on the eastern part of the island in Unai Dankulo (NPS, 2001). Reichel (1991) reported over 270 pairs of breeding seabirds on Tinian, including 150 pairs of White Terns.

Recommended citation
BirdLife International (2023) Important Bird Areas factsheet: Tinian Island. Downloaded from on 26/03/2023.