Data Zone
| Country/Territory | Micronesia, Federated States of |
| Area | 120 km2 |
| Altitude | 0 - 100 m |
| Priority | high |
| Habitat loss | major |
| Knowledge | incomplete |
The state of Yap in the western Pacific comprises four main volcanic and metamorphic islands separated by narrow channels: Yap (which has the highest peak at 176 m), Gagil Tomil, Maap and Rumung. The Federated States of Micronesia includes other island states (Truk, Pohnpei and Kosrae) c.1,500 km to the east, but these are treated separately in one EBA, the East Caroline Islands (EBA 192).
At one time broadleaf deciduous forests are thought to have largely covered the Yap islands, but, since the arrival of aboriginal people, this habitat has been destroyed or greatly altered, and now savanna and grassland are common, and virtually all remaining forest is secondary (a mixture of both native and cultivated species) and scrubby in nature (Engbring et al. 1990). Mangrove swamps are found around all the islands in sheltered, shallow, coastal situations.
Restricted-range speciesMost of the restricted-range species occur in a variety of habitats, including all forest types and secondary vegetation, though few native birds use savanna extensively. Four of the restricted-range species occur more widely in the Micronesian region (which includes four EBAs, 189-192), but do not show clear affinities to any one EBA, and thus Yap has been treated as an EBA in its own right.
| Country | IBA Name | IBA Book Code |
|---|---|---|
| Micronesia, Federated States of | Yap Island | FSM016 |
Given their small ranges, and despite their large populations, all of the endemic species of this EBA are at risk from introduced species. Main cause for concern is the possible future introduction of the brown tree snake Boiga irregularis, which has caused the extinction of many bird species on Guam (see Mariana Islands, EBA 189).
Concern has also been expressed that the Tree Sparrow Passer montanus, introduced in the late 1970s from Eurasia, may carry exotic diseases which could seriously affect the native avifauna (Engbring et al. 1990); however, earlier introductions of other bird species have apparently had no drastic effects, and, as Yap receives migrants regularly, continental diseases have probably been present for some time and are unlikely to be a significant threat (H. D. Pratt in litt. 1995). Loss of habitat from fire is an additional threat as, during the dry season, large areas of savanna are torched by local people for various reasons (B. Raynor in litt. 1995).
Zosterops oleagineus is the scarcest of the endemic species, with a population estimated at less than 20,000 in 1984 and some evidence of a decline since the 1970s; it has therefore been classified as threatened. The two other endemics are regarded as Near Threatened.Several subspecies endemic to this EBA qualify as threatened. One example is Yap Cicadabird Coracina tenuirostris nesiotis (a good candidate for elevation to species rank), which is very rare and thinly distributed in forest (H. D. Pratt in litt. 1994). A race of Common Moorhen Gallinula chloropus which has nested in small numbers on Yap in recent years is also a threatened subspecies if it has colonized from the Marianas-though not if it has come from Palau or the Asian mainland (see Stinson et al. 1991, H. D. Pratt in litt. 1995).
Although there are no legally protected areas in this EBA (all land is privately owned), the use of natural resources has been regulated by customary management. However, as elsewhere in the Pacific, such control is likely to be increasingly challenged and to become difficult to maintain. A general policy of regular forest maintenance has therefore been recommended, including standard forestry practices such as controlling fires, and replanting and reclaiming portions of savanna. It is difficult to provide more specific recommendations, such as the identification of specific areas that are of more conservation value than others, because birds are found throughout the remaining forest (Engbring et al. 1990).
Recommended citation
BirdLife International (2024) Endemic Bird Area factsheet: Yap Islands. Downloaded from
https://datazone.birdlife.org/eba/factsheet/190 on 23/11/2024.