Recovery Plan for Two Plants from Rota

U.S. Fish & Wildlife Service Recovery Plan for Two Plants from Rota ©Gregory A Koob, used with permission. DISCLAIMER Recovery plans delineate reasonable actions that are believed to be required to recover and protect listed species. We, the U.S. Fish and Wildlife Service, prepare and publish recovery plans, sometimes with the assistance of recovery teams, contractors, State agencies, Tribal agencies, and other affected and interested parties. The objectives of recovery plans 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. Recovery plans do not obligate other parties to undertake specific actions and may not represent the views nor the official positions or approval of any individuals or agencies involved in recovery plan formulation, other than our own. They represent our official position only after they have been signed by the Regional Director or Director as approved. Recovery plans are reviewed by the public and submitted to peer review before we adopt them as approved final documents. Approved recovery plans are subject to modification as dictated by new findings, changes in species status, and the completion of recovery actions. Literature citation of this document should read as follows: U.S. Fish and Wildlife Service. 2007. Recovery Plan for Two Plants from Rota (Nesogenes rotensis and Osmoxylon mariannense). Portland, Oregon. 86 pp. An electronic copy of this plan is available at: <http://pacific.fws.gov/ecoservices/endangered/recovery/default.htm> and also at <http://endangered.fws.gov/recovery/index.html>. i ACKNOWLEDGMENTS This recovery plan was prepared by the U.S. Fish and Wildlife Service’s Pacific Islands Fish and Wildlife Office in cooperation with the Commonwealth of the Northern Mariana Islands Department of Lands and Natural Resources. Its completion would not have been possible without their assistance. Many individuals and organizations have contributed to our knowledge of Nesogenes rotensis and Osmoxylon mariannense and work cooperatively with us to recover these species. We would especially like to thank the following individuals for their support: James Manglona, Lynn Raulerson, Estanislao Taisacan, and Laura Williams. ii EXECUTIVE SUMMARY Current Status: The plants Nesogenes rotensis and Osmoxylon mariannense (no common names) are found only on the island of Rota in the Commonwealth of the Northern Mariana Islands (CNMI). Nesogenes rotensis is a low-growing herbaceous plant in the verbena family (Verbenaceae) and Osmoxylon mariannense is a spindly, soft-wooded tree in the ginseng family (Arialiaceae). Both species were federally listed as endangered in 2004 (U.S. Fish and Wildlife Service [USFWS] 2004). Osmoxylon mariannense is also protected by the government of the Commonwealth of the Northern Mariana Islands. Currently, there are 2 known populations of N. rotensis of 15 to 20 plants each. The 10 known individuals of O. mariannense are in scattered locations on the Sabana (the cloudswept plateau that dominates the western half of Rota). Habitat Requirements: Nesogenes rotensis is found on exposed, raised limestone flats in non-forested coastal strand habitat. These flats are subject to salt spray during severe storms. Osmoxylon mariannense is found in limestone forests on the Sabana, a raised plateau unique in the Mariana archipelago, that are often shrouded in clouds and mist. Limiting Factors: Human activities that alter native vegetation and habitat are believed to be the primary factors leading to the small population sizes and limited distribution of Nesogenes rotensis and Osmoxylon mariannense. These activities include agriculture, ranching, nonnative plant and animal introductions, resort and beach park development in the coastal habitat of N. rotensis, and road construction and maintenance in the Sabana habitat of O. mariannense. In the last decade, several major typhoons have made landfall on Rota, severely impacting individuals of both species. Another factor that may affect the recovery of these two species is their vulnerability to extinction from reduced reproductive vigor due to their small population sizes. iii Recovery Strategy: Recovery of Nesogenes rotensis and Osmoxylon mariannense focuses on the following actions: (1) protecting and restoring the native coastal strand and forest habitat of N. rotensis and O. mariannense, respectively; (2) establishing new populations and augmenting existing populations of these species through methods including controlled propagation and outplanting; (3) assessing the impacts of feral ungulates (deer and pigs), rats, mice, insects, diseases, and introduced plants, and determining methods for their appropriate control or eradication; (4) building public support for conservation; and (5) reassessing and refining recovery actions as appropriate. Recovery Priority Numbers: Nesogenes rotensis has a recovery priority number of 2 on a scale of 1 (highest) to 18 (lowest), reflecting a high degree of threat, high recovery potential, and its taxonomic status as a full species. Osmoxylon mariannense has a recovery priority number of 5, reflecting a high degree of threat, low recovery potential, and its taxonomic status as a full species. Recovery Goals: The interim goal is to control threats and increase population sizes and geographic distribution sufficient to reclassify or downlist these two endangered species to threatened status. The long-term goal is to conserve and recover Nesogenes rotensis and Osmoxylon mariannense in order to remove them from the Federal List of Endangered and Threatened Wildlife and Plants (delisting). Recovery Objectives: Restore and maintain multiple naturally reproducing populations of Nesogenes rotensis and Osmoxylon mariannense on the island of Rota such that the protections of the Endangered Species Act are no longer necessary. Recovery Criteria: Nesogenes rotensis and Osmoxylon mariannense may be considered for downlisting to threatened status when all of the following criteria are achieved and maintained for a minimum of 10 consecutive years: iv 1) A total of two populations of Nesogenes rotensis are naturally reproducing and stable, or increasing in numbers. Each population of N. rotensis must consist of at least 300 mature, reproducing individuals. A total of two populations of Osmoxylon mariannense are naturally reproducing and stable, or increasing in numbers. Each population of O. mariannense must consist of at least 100 mature, reproducing individuals. A stable or increasing population is defined as having a finite rate of increase (known as 8 or lambda) greater than or equal to 1 over the requisite 10-year time period. 2) Sufficient habitat is protected and managed to achieve criterion 1 above. 3) Management and control of nonnative species by local, regional, Commonwealth, and Federal authorities are demonstrated to be successful and sufficient to achieve criterion 1 above. Nesogenes rotensis and Osmoxylon mariannense may be considered for removal (delisting) from the Federal List of Endangered and Threatened Wildlife and Plants when all of the following criteria are achieved and maintained for a minimum of 10 consecutive years: 1) A total of four populations of Nesogenes rotensis are naturally reproducing and stable, or increasing in numbers. Each population of N. rotensis must consist of at least 300 mature, reproducing individuals. A total of four populations of Osmoxylon mariannense are naturally reproducing and stable, or increasing in numbers. Each population of O. mariannense must consist of at least 100 mature, reproducing individuals. A stable or increasing population is defined as having a finite rate of increase (known as 8 or lambda) greater than or equal to 1 over the requisite 10-year time period. 2) Sufficient habitat is protected and managed to achieve criterion 1 above. v 3) Management and control of nonnative species by local, regional, Commonwealth, and Federal authorities are demonstrated to be successful and sufficient to achieve criterion 1 above. Recovery Actions Needed: 1) Coordinate and monitor recovery efforts; 2) Address factors affecting viability of the wild populations; 3) Monitor the extant Nesogenes rotensis and Osmoxylon mariannense populations, establish new populations, and augment existing populations; and 4) Provide educational and informational opportunities to build public support for conservation. Date of Recovery: Due to the present uncertainties regarding the roles of introduced species, habitat loss and degradation, and the susceptibility of the wild populations to random catastrophic events, we cannot realistically estimate when delisting of Nesogenes rotensis and Osmoxylon mariannense might occur. We expect that it will likely take several decades to fully recover these species, depending on the status of controlling threats to the species and the status of their populations. As we implement the recovery actions in this plan we anticipate that we will be able to more accurately estimate when delisting might occur. Total Estimated Cost of Recovery: Due to the great number of unknown variables affecting the management and potential recovery of these two species, the total cost to recover Nesogenes rotensis and Osmoxylon mariannense cannot be realistically determined at this time. Future recovery actions will be initiated, implemented, and modified as informed by research and monitoring of ongoing management actions (see Recovery Actions

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