March 2009 ECOLOGICAL RESTORATION 27:1 • 27 Ecological Restoration Vol. 27, No. 1, 2008 ISSN 1522-4740 E-ISSN 1543-4079 ©2008 by the Board of Regents of the University of Wisconsin System. UW Press / Ecological Restoration CASE STUDY Seabird Habitat Restoration on Praia Islet, Azores Archipelago Joël Bried, Maria C. Magalhães, Mark Bolton, Verónica C. Neves, Elizabeth Bell, José C. Pereira, Luís Aguiar, Luís R. Monteiro and Ricardo S. Santos ABSTRACT As on many other islands, most of the seabird species breeding in Portugal’s Azores archipelago are now restricted to tiny remnants of their former nesting range, owing in large part to the introduction of mammals by humans. Praia Islet, 0.12 km² in size, is home to five seabird species, four of which fall under the European listing of “conservation concern.” Introduced rabbits (Oryctolagus cuniculus) on Praia had accelerated soil erosion through overgrazing, destroyed seabird nests, and competed for burrows with petrels. Restoration of seabird habitat on the islet began in 1995 and involved rabbit eradication, control of soil erosion, native plant reintroduction, and installation of artificial nests for common terns (Sterna hirundo), roseate terns (Sterna dougallii), and Madeiran storm-petrels (Oceanodroma castro). Rabbits were eradicated in 1997 using broadcast pellets containing poison. Since then, soil erosion has decreased, many of the reintroduced native plants have started to spread, and tern and Madeiran storm-petrel breeding numbers on the islet have increased by 1,548% and 43%, respectively. However, Praia Islet seabirds remain vulnerable owing to human recreational activities. This case study highlights the need to consider local conditions carefully when assessing restoration options to effect rapid mammal eradication. It also confirms the value of combining measures aimed at restoring native vegetation and improving seabird habitat quality with alien herbivore eradication. Keywords: Azores, European rabbit (Oryctolagus cuniculus), island habitat restoration, rabbit eradication, seabirds A nthropogenic species introduc- tions represent the main cause of extinctions on islands (Clout and Veitch 2003). Because many seabird species evolved in areas to which mam- mals had limited or no access (oceanic islands, inaccessible mainland clifs), they lack behavioral or ecological adaptations to cope successfully with alien predators or with perturbations of their nesting habitat, making them especially vulnerable to mammalian introductions (Lack 1968, Burger and Gochfeld 1994). he Azores archipelago, located in the subtropical northern Atlan- tic (Figure 1), currently holds eight seabird species. Many of these were extirpated from the nine main islands with the introduction of 16 mammal species by Portuguese settlers begin- ning in the 15th century (Le Grand 1993, Monteiro et al. 1996), and are now restricted to a few islets and remote coastal strips. Currently, six out of these eight species are consid- ered “of Conservation Concern” in Europe (BirdLife International 2004, Table 1). While the area and topography of the nine islands, combined with the presence of large human populations, currently preclude mammal eradica- tion and large-scale habitat restora- tion, such operations are possible on the smaller islets, which can there- after serve as refugia for the native fauna. On Praia Islet (Figure 1), rabbits (Oryctolagus cuniculus) were introduced about 50 years ago. As on the other approximately 800 islands worldwide where rabbits have been introduced (Courchamp et al. 2003), their impact has been catastrophic, as they depleted native vegetation relied upon by nesting birds and chicks, increased soil erosion, and competed for burrows with petrels (Bell et al. 1997, Monteiro 2000). he importance of Praia Islet for seabirds (Table 1), associated with the underrepresentation of native vascular plant species (pteridophytes, gymno- sperms, and angiosperms) on the near- est island, Graciosa, as compared to the eight other islands (Borges et al. 2005), ofered a unique opportunity to conduct what is to our knowledge the irst habitat restoration campaign involving rabbit eradication, reduc- tion of soil erosion, reintroduction of indigenous plants, and long-term monitoring of reintroduced plants and vulnerable seabirds. Because prevail- ing winds blow from Graciosa to the neighboring Praia and Baixo islets, and the distance from Graciosa to each of these islets is quite short (0.8–1 km), the plant community on these islets before rabbits were introduced 2-ER27.1 Bried (27-36).indd 27 12/18/08 1:16 PM