Monographs of the Western North American Naturalist Volume 7 8th California Islands Symposium Article 37 12-31-2014 Reintroduction of historically extirpated taxa on the California Channel Islands Scott A. Morrison The Nature Conservancy, San Francisco, CA, [email protected] Kevin A. Parker Institute of Natural Sciences, Massey University, [email protected] Paul W. Collins Santa Barbara Museum of Natural History, Santa Barbara, CA, [email protected] W. Chris Funk Colorado State University, Fort Collins, CO, [email protected] T. Scott iS llett Migratory Bird Center, Smithsonian Conservation Biology Institute, National Zoological Park, Washington, DC, [email protected] Follow this and additional works at: https://scholarsarchive.byu.edu/mwnan Recommended Citation Morrison, Scott A.; Parker, Kevin A.; Collins, Paul W.; Funk, W. Chris; and Sillett, T. Scott (2014) "Reintroduction of historically extirpated taxa on the California Channel Islands," Monographs of the Western North American Naturalist: Vol. 7 , Article 37. Available at: https://scholarsarchive.byu.edu/mwnan/vol7/iss1/37 This Monograph is brought to you for free and open access by the Western North American Naturalist Publications at BYU ScholarsArchive. It has been accepted for inclusion in Monographs of the Western North American Naturalist by an authorized editor of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. Monographs of the Western North American Naturalist 7, © 2014, pp. 531–542 REINTRODUCTION OF HISTORICALLY EXTIRPATED TAXA ON THE CALIFORNIA CHANNEL ISLANDS Scott A. Morrison1,6, Kevin A. Parker2, Paul W. Collins3, W. Chris Funk4, and T. Scott Sillett5 ABSTRACT.—Most invasive alien vertebrate populations on the Channel Islands of California have been eradicated over the past 30 years. Unfortunately, removal of these introduced herbivores or predators came too late for some native flora and fauna, and numerous populations are now extinct. Here, we describe a systematic approach to reintroducing extirpated native taxa as a means for rebuilding natural communities and enhancing the resiliency of island ecosystems. Reintroduction efforts typically focus on a single species or site. In contrast, we propose that if reintroduction is a shared conservation goal of managers across the islands, the associated planning, implementation, and monitoring should be conducted as a cross-island initiative for the archipelago. A coordinated effort based on best practices in reintroduction biology could accrue programmatic efficiencies and economies of scale, more quickly advance ecosystem and species conservation goals, and create unique opportunities to test hypotheses in basic and applied ecology and evolution. The philosophical and technical approaches developed through this program may apply to other island and mainland sys- tems and could be adapted to develop conservation strategies for species that may be candidates for assisted coloniza- tion in the face of climate change. RESUMEN.—La mayoría de las poblaciones invasoras de vertebrados no nativas en las Islas del Canal de California han sido erradicadas durante los últimos 30 años. Desafortunadamente, la eliminación de estos herbívoros o depredadores exóticos llegó demasiado tarde para algunas especies de fauna y flora nativa, y numerosas poblaciones están ahora extin- tas. Describimos un enfoque sistemático para reintroducir taxa autóctonos eliminados como un medio de reconstruir las comunidades naturales y mejorar la resistencia de los ecosistemas de las islas. Los esfuerzos de reintroducción típica- mente se centran en una sola especie o lugar. Por el contrario, nosotros proponemos que si la reintroducción es un obje- tivo de conservación compartido por los administradores de recursos en todas las islas, la planificación asociada, la implementación y el monitoreo deben ser conducidos como una iniciativa entre islas del archipiélago. Un esfuerzo coor- dinado, basado en mejores prácticas de biología de reintroducción, podría conjuntar eficiencia del programa y economías de escala, hacer que los objetivos de conservación de los ecosistemas avancen más rápidamente y crear opor- tunidades únicas de comprobar hipótesis sobre ecología y evolución básica y aplicada. Los enfoques filosóficos y técni- cos desarrollados a través de este programa podrían aplicarse a otros sistemas de islas y de continentes, y podrían ser adaptados para desarrollar estrategias de conservación para aquellas especies que pudieran ser candidatas para la colo- nización asistida en caso de cambio climático. Advances in the eradication of invasive Reintroducing locally extinct populations on vertebrates from islands have improved our islands free of harmful invasive species can ability to conserve insular biodiversity (Veitch be an important management strategy for and Clout 2002, Veitch et al. 2011). Eradica- restoring island ecosystems and conserving tion, however, generally represents only the native species (Ewen et al. 2012). initial phase of an island restoration program. The Channel Islands of California have After eradication, managers must decide what been the focus of much ecological restoration desired state they will manage toward over effort, including invasive species eradication the long term (Hobbs and Norton 1996, Hay- (McEachern et al. in press). The Channel ward 2009). For example, managers might Islands are a loose archipelago of 8 islands assess the desirability, feasibility, and priority that range in size from 260 ha (Santa Barbara of reconstituting the full complement of native Island) to 250 km2 (Santa Cruz Island) and species that was present on the island prior from 20 km (Anacapa Island) to 120 km (San to the introduction of invasive vertebrates. Nicolas Island) in distance to the mainland. 1The Nature Conservancy, 201 Mission St., 4th Floor, San Francisco, CA 94105. 2Institute of Natural Sciences, Massey University, Private Bag 102904, North Shore Mail Centre, Auckland, New Zealand. 3Santa Barbara Museum of Natural History, 2559 Puesta Del Sol, Santa Barbara, CA 93105. 4Department of Biology, Graduate Degree Program in Ecology, Colorado State University, Fort Collins, CO 80523. 5Migratory Bird Center, Smithsonian Conservation Biology Institute, National Zoological Park, Box 37012, MRC 5503, Washington, DC 20013. 6E-mail: [email protected] 531 532 MONOGRAPHS OF THE WESTERN NORTH AMERICAN NATURALIST [Volume 7 Ownership is mostly federal (U.S. Department to be identified (Parker et al. 2010). Develop- of Defense, U.S. National Park Service) and ing experience not only in the science and nonprofit conservation organizations (The practice but also in the philosophy and policy Nature Conservancy [TNC], Catalina Island of conservation translocations may become Conservancy). Although the terrestrial and increasingly important because, with climate marine environments of the islands have been change, managers will face decisions about affected by human activities for millennia, the assisting the colonization of species outside 19th and 20th centuries—generally catego- of their indigenous range to facilitate adapta- rized as the “ranching era”—had an especially tion (Seddon 2010, IUCN/SSC 2013). profound ecological impact (Rick et al. 2014). Introduced herbivores and predators degraded WHY REINTRODUCE EXTINCT POPULATIONS? island habitats and imperiled many plant and animal species. Populations of a variety of Reintroducing populations on the Califor- taxa disappeared (PWC unpublished data), nia Islands would be elective and therefore including numerous passerine birds (Table 1). warrants articulating reasons for reintroduc- Island managers across the archipelago have tion to help prioritize it as a management implemented numerous projects aimed at action. Below, we discuss potential reasons eradicating ecologically harmful introduced to reintroduce extirpated taxa, which include species (McEachern et al. in press). These considerations of ecological function, species efforts over the past 3 decades have con- viability and adaptation, as well as ethical con- tributed to the recovery of some native vege- siderations, such as a desire to undo perceived tation communities (e.g., Beltran et al. 2014) damage caused by humans. Potential reasons and imperiled animal populations (e.g., Whit- not to reintroduce populations include oppor- worth et al. 2005, Coonan et al. 2010, Sillett tunity costs of diverting limited conservation et al. 2012). Some invasive animal species resources from other conservation manage- (e.g., Randall et al. 2011, McEachern et al. in ment priorities, and risks (e.g., of the translo- press) and numerous invasive plant species cation causing harm to the relocated species (e.g., Corry and McEachern 2009, Cory and or to other species on the destination island). Knapp 2014) remain; but all of the islands Such risks should be addressed in planning, are now managed for protection of natural which we discuss in the subsequent section. resources, and their ecological trajectories Societal Values and Precedent are generally more toward resilience than degradation (Rick et al. 2014). For some A general management goal for many of the Channel Islands species, however, the current islands is a return to conditions that existed “conservation management era” came too late. prior to the ranching era. This goal stems from Here, we discuss reintroducing taxa that an awareness that relatively recent human were historically extirpated from the Channel activities