U.S. Fish & Wildlife Service Recovery Plan for the Nosa Luta or Rota Bridled White-Eye (Zosterops rotensis) Rota bridled white-eye at nest; photo by Fred Amidon, U.S. Fish and Wildlife Service Recovery Plan for the Nosa Luta or Rota Bridled White-Eye (Zosterops rotensis) Region 1 U.S. Fish and Wildlife Service Portland, Oregon DISCLAIMER Recovery plans delineate actions which the best available science indicates are required to recover and protect listed species. Plans are published by the U.S. Fish and Wildlife Service, sometimes prepared with the assistance of recovery teams, contractors, State agencies, and others. Recovery teams serve as independent advisors to the U.S. Fish and Wildlife Service. Recovery plans are reviewed by the public and submitted to additional peer review before they are approved and adopted by the U.S. Fish and Wildlife Service. Objectives will be attained and any necessary funds made available subject to budgetary and other constraints affecting the parties involved, as well as the need to address other priorities. Nothing in this plan should be construed as a commitment or requirement that any Federal agency obligate or pay funds in contravention of the Anti-Deficiency Act, 31 USC 1341, or any other law or regulation. Recovery plans do not necessarily represent the views nor the official positions or approval of any individuals or agencies involved in the plan formulation, other than the U.S. Fish and Wildlife Service. Recovery plans represent the official position of the U.S. Fish and Wildlife Service only after they have been signed as approved by the Regional Director or Director. Approved recovery plans are subject to modification as dictated by new findings, changes in species status, and the completion of recovery actions. Please check for updates or revisions at the website address(s) provided below before using this plan. Literature citation of this document should read as follows: U.S. Fish and Wildlife Service. 2007. Recovery Plan for the Nosa Luta or Rota Bridled White-eye (Zosterops rotensis). Portland, Oregon. xi + 136 pp. An electronic copy of this plan will be made available at: <http://pacific.fws.gov/ecoservices/endangered/recovery/default.htm> and also at <http://endangered.fws.gov/recovery/index.html>. i PRIMARY AUTHORS Fred Amidon of the Pacific Islands Fish and Wildlife Office, U.S. Fish and Wildlife Service, Honolulu, Hawai`i, prepared this recovery plan. All outreach recovery actions within this plan were developed by Ken Foote, Pacific Islands Fish and Wildlife Office. The monitoring program for the Rota bridled white-eye presented in this plan was developed by Rick Camp, Hawai`i Cooperative Studies Unit, University of Hawai`i. All maps within this plan were developed with the assistance of Mark Metevier, Pacific Islands Fish and Wildlife Office, U.S. Fish and Wildlife Service. Recovery plan preparation was supervised and edited by Marilet A. Zablan, Gina Shultz, and Patrick Leonard, Pacific Islands Fish and Wildlife Office, U.S. Fish and Wildlife Service. ACKNOWLEDGMENTS Many individuals and organizations have contributed to the recovery program for the nosa Luta or Rota bridled white-eye. We would especially like to thank the following individuals for their assistance and support: Jeff Burgett (U.S. Fish and Wildlife Service), Scott Derrickson (National Zoo), Nate Hawley (U.S. Fish and Wildlife Service), Curt Kessler (U.S. Fish and Wildlife Service), Shelly Kremer (U.S. Fish and Wildlife Service; formerly of the Commonwealth of the Northern Mariana Islands, Division of Fish and Wildlife), Peter Luscomb (Honolulu Zoo), William McDowell (Audubon Zoo), John Morton (U.S. Fish and Wildlife Service), Bill Rameyer (U.S. Geological Survey), Thalia Sachtleben (Colorado State University), and Estanislao Taisacan (Commonwealth of the Northern Mariana Islands, Division of Fish and Wildlife – retired). We would also like to acknowledge the many researchers whose efforts have helped bring insight into the biology and conservation of the nosa Luta. Finally we would like to thank the three peer reviewers who provided comments on the draft recovery plan. ii EXECUTIVE SUMMARY Current Status: The Rota bridled white-eye or nosa Luta in the Chamorro language (Zosterops rotensis) was listed as endangered in 2004 (U.S. Fish and Wildlife Service [USFWS] 2004). As of August 1999, the population on Rota was approximately 1,000 birds and the species’ core range consisted of approximately 254 hectares (628 acres) of forest above 150 meters (490 feet) elevation. This population estimate is approximately 90 percent lower then the population estimate of over 10,000 birds in 1982 (Engbring et al. 1986). The nosa Luta has a recovery priority number of 2 on a scale of 1 (highest) to 18 (lowest), reflecting a high degree of threat, strong prospects for recovery, and its taxonomic status as a full species. Habitat Requirements and Distribution: The nosa Luta is endemic to the island of Rota, Commonwealth of the Northern Mariana Islands. Currently, the species is primarily restricted to mature forests above 150 meters (490 feet) in the Sabana region of Rota. These forests are divided into the following three types based on dominant canopy tree species: (1) mixed oschal (Hernandia labyrinthica; a native species) and yoga (Elaeocarpus joga; a native species) forest; (2) faniok (Merrilliodendron megacarpum; a native species) forest; and (3) sosugi (Acacia confusa; an introduced species) forest. Nosa Luta primarily forage in the outer canopy of forests for insects, fruit, or nectar and the majority of the foraging observations have been reported in Elaeocarpus joga, Hernandia labyrinthica, pengua (Macaranga thompsonii; a native species), Merrilliodendron megacarpum, and ahgao (Premna obtusifolia; a native species). Nosa Luta nests have been reported in Merrilliodendron megacarpum, Hernandia labyrinthica, Elaeocarpus joga, and Acacia confusa trees 3 to 15 meters (10 to 49 feet) tall and 2 to 60 centimeters (1 to 24 inches) in diameter. Threats to Species Recovery: Current threats include habitat loss and degradation and susceptibility of the single small population to random catastrophic events, such as typhoons. Predation by introduced rats (Rattus spp.) and black drongos (Dicrurus macrocercus) may also be threatening the long-term conservation of this species. In addition, the establishment of a new predator, such as the brown treesnake (Boiga irregularis), or avian diseases, such as west Nile virus, would also threaten the recovery of the species. iii Recovery Strategy: Recovery actions in this plan are designed to address the threats to the nosa Luta in order to achieve the recovery goals for this species. Recovery actions focus on addressing predation by introduced species, preventing the establishment of new predators and avian diseases, protecting and restoring native forests within the nosa Luta’s range, and evaluating the need for establishing a second population. The impact of black drongo and rat predation on the nosa Luta population is uncertain. This level of impact will be assessed and used to determine how to prioritize control and eradication activities for these introduced species. Preventing the introduction of new predators, such as the brown treesnake, and new avian diseases, such as west Nile virus, are intended to prevent additional declines in the population while current threats are addressed. Protecting forest habitat within the nosa Luta’s range is intended to reduce the decline in available habitat by working with private landowners and public land managers on Rota. Restoring forested habitat within the nosa Luta’s range includes developing and implementing forest restoration programs in the Sabana region of Rota. Evaluating the need for establishing a second population is intended to determine if and at what point a captive propagation or translocation program is needed to help prevent the species from going extinct due to random catastrophic events. Recovery Goals and Objectives: The goal of the nosa Luta recovery program is to downlist the species to threatened status and ultimately to remove the species from the Federal list of Endangered and Threatened Wildlife and Plants (delist). Due to the limited information available to inform long-term recovery planning efforts, the recovery program presented in this plan focuses on the first 10 years of the recovery process, with the immediate goal of halting the population decline of the nosa Luta and preventing the extinction of the species. The primary interim objectives of this recovery plan over the next 10 years are to stop further declines in the range and composition of the nosa Luta population, develop safeguards to prevent the species from going extinct, reverse population declines, and restore the population to at least the abundance level estimated in 1982 (10,000 individuals). At this time, we have developed only interim downlisting targets for the nosa Luta due to data limitations and potential uncertainties associated with attempting to define more specific and quantitative recovery criteria. Recovery iv actions intended to acquire the information needed to develop appropriate recovery criteria within the next 10 years are identified in this recovery plan. The population targets for downlisting offered here should be revised, if necessary, based upon new data gathered during this time. At present, the interim downlisting objectives for the nosa Luta over the next 10 years are as follows: (1) Arrest the decline in abundance