Country/territory: Northern Mariana Islands (to USA)

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

Area: 4,904 ha

Most recent IBA monitoring assessment
Year of assessment Threat score (pressure) Condition score (state) Action score (response)
2007 high not assessed not assessed
For more information about IBA monitoring please click here

Site description
The proposed IBA on Rota includes those areas that have been deemed feasible for management under the US National Park system. The IBA includes large areas of native forest and the USFWS-designated Critical Habitats for the Rota Bridled White-Eye and the Mariana Crow. Several cultural sites are included in the proposed IBA. Parts of the proposed IBA are currently protected by CNMI law. Because of Rota’s remaining native forest, several rare, endangered, and endemic species are known to occur in the proposed IBA.

Key biodiversity
Rota has two threatened birds that are restricted in range. The Rota Bridled White-Eye (formerly classified as a subspecies of Bridled White-Eye in Engbring et al. (1986) but later separated as its own species) is endemic to Rota and listed as Critically Endangered due to declining populations. Decline of the Rota Bridled White-Eye is in part due to predation by introduced species such as the Black Drongo and rats and in part due to habitat loss and degradation (USFWS, 2004; Craig, 1999). A small population size and limited distribution also increase the species vulnerability (USFWS, 2004). In 2004 there had been two captures of the Brown Treesnake on Rota (Campbell, 2004). The Mariana Crow, originally restricted to Guam and Rota, is listed as Endangered. The population in Guam was extirpated, although in 2005 10 birds were transplanted from Rota and did survive on Guam (Aguon et al., 2005). Declines of the Mariana Crow on Guam are largely attributed to the Brown Treesnake (Wiles et al., 2003), but introduced predators, human persecution, and habitat loss and degradation have all contributed to the decline (Plentovich et al., 2005). In 1982 Engbring et al. (1986) estimated the population of Rota Bridled White-Eyes to number over 10,000. The species was found in several areas, but generally above 300 meters in elevation. By 1996 the population numbered only over 1000 birds and was restricted to four patches of mature wet forest above 200 m (Fancy and Snetsinger (2001) in USFWS (2004)) (Figure 3). Craig (1999) wrote that the bird was restricted to the Sabana plateau region of Rota. In 1982 Engbring et al. (1986) found Mariana Crows to be distributed throughout Rota with a population of over 1300 birds. In 2004 there were only an estimated 85 pairs remaining (Aguon et al., 2005). In 2004 the USFWS (2004) designated Critical Habitat for the Mariana Crow. This habitat included expected recovery zones. Tanaka and Haig (2004) did not detect Mariana Common Moorhens during surveys, but did report several sightings, including evidence of breeding (Worthington, 1998), of the birds on golf course wetlands and ephemeral streams. Reichel (1991) reported 445 pairs of breeding seabirds for Rota, including 200 pairs of Red-footed Boobies and 100 pairs of Brown Noddies.

Non-bird biodiversity: Several rare, endangered, and endemic species are known to occur in the proposed IBA, including: • Endangered plants o Osmoxylon mariannenese o Nesogenese rotensis o Serianthes nelsonii o Tabernaemontana rotensis(candidate endangered species) • Mariana Fruit Bats • Fragile Tree Snail • A translocated population of Guam Rails (introduced to Rota)

Recommended citation
BirdLife International (2022) Important Bird Areas factsheet: Rota. Downloaded from on 29/09/2022.