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This paper develops a model of invasive species control when the species’ population size is unknown. In the face of an uncertain population size, a resource manager’s species-control efforts provide two potential bene ts: (1) a direct bene t of possibly reducing the population of invasive species, and (2) an indirect bene t of information acquisition (due to learning about the population size, which reduces uncertainty). We provide a methodology that takes into account both of these bene ts, and show how optimal management decisions are altered in the presence of the indirect bene t of learning. We then apply this methodology to the case of controlling the Brown Treesnake (Boiga irregularis) on the island of Saipan. We nd that the indirect bene t—the value of information to reduce uncertainty—is likely to be quite large.

Rattus rattus, or black rats, are rampaging through Tuvalu's atolls and gnawing through the country's chief export crop - coconuts. Coconuts and copra (dried coconut flesh from which coconut oil is made) are the islander's main source of revenue.

Questions: Do past disturbance, soil nutrients, or species diversity predict the invasion success of the alien tree Pittosporum undulatum in an island montane rain forest? What are the consequences of its invasion for forest composition and species diversity? Location: Blue Mountains, Jamaica. Methods: Censuses of trees ? 3 cm DBH in permanent plots in four sites within ca. 7 ha; 1974–2004 (intensive sites) and in 16 plots within 250 ha; 1990–2004 (extensive plots). Results: Pittosporum was unrecorded in the intensive sites before a severe hurricane in 1988: by 2004 all four sites were invaded. Pittosporum had invaded 25% of the extensive plots in 1990 and 69% in 2004, where its basal area increased from 0.5 ± 0.4 (SEM) m2.ha?1 in 1990 to 2.8 ± 1.3 m2.ha?1 in 2004. It had zero stem mortality and diameter growth rate exceeded that of native species fourfold. Pittosporum's basal area in the extensive plots in 2004 was positively related to the stand basal area damaged in the 1988 hurricane and negatively related to soil N concentrations. Pittosporum invasion was unrelated to stand-level tree species diversity in the extensive plots but as its basal area increased over time the basal area of native species and stand-level diversity declined. Conclusions: There are no obvious functional attributes of Pittosporum unrepresented in the native tree flora although it has high photosynthetic efficiency compared with native trees. More widespread invasion of these forests by Pittosporum seems inevitable since hurricanes, which accelerated the invasion, affect these forests frequently.

Disturbances are a primary facilitator of the growth and spread of invasive species. However, the effects of large-scale disturbances, such as hurricanes and tropical storms, on the broad geographic patterns of invasive species growth and spread have not been investigated. We used historical aerial imagery to determine the growth rate of invasive Phragmites australis patches in wetlands along the Atlantic and Gulf Coasts of the United States. These were relatively undisturbed wetlands where P. australis had room for unrestricted growth. Over the past several decades, invasive P. australis stands expanded in size by 6–35% per year. Based on tropical storm and hurricane activity over that same time period, we found that the frequency of hurricane-force winds explained 81% of the variation in P. australis growth over this broad geographic range. The expansion of P. australis stands was strongly and positively correlated with hurricane frequency. In light of the many climatic models that predict an increase in the frequency and intensity of hurricanes over the next century, these results suggest a strong link between climate change and species invasion and a challenging future ahead for the management of invasive species.

Invading alien species in the United States cause major environmental damages and losses adding up to almost $120 billion per year. There are approximately 50,000 foreign species and the number is increasing. About 42% of the species on the Threatened or Endangered species lists are at risk primarily because of alien-invasive species.

We conducted ant surveys on Santa Cruz Island, the largest of the California Channel Islands, in 1975/6, 1984, 1993 and 1998. Our surveys yielded a combined total of 34 different ant species: Brachymyrmex cf. depilis, Camponotus anthrax, C. clarithorax, C. hyatti, C. semitestaceus, C. vicinus, C. sp. near vicinus, C. yogi, Cardiocondyla ectopia, Crematogaster californica, C. hespera, C. marioni, C. mormonum, Dorymyrmex bicolor, D. insanus (s.l.), Formica lasioides, F. moki, Hypoponera opacior, Leptothorax andrei, L. nevadensis, Linepithema humile, Messor chamberlini, Monomorium ergatogyna, Pheidole californica, P. hyatti, Pogonomyrmex subdentatus, Polyergus sp., Prenolepis imparis, Pseudomyrmex apache, Solenopsis molesta (s.l.), Stenamma diecki, Sn. snellingi, S. cf. diecki, and Tapinoma sessile. The ant species form a substantial subset of the mainland California ant fauna. We found only two ant species that are not native to North America, C. ectopia and L. humile. Linepithema humile, the Argentine ant, is a destructive tramp ant that poses a serious threat to native ants.

We assessed the distribution, relative abundance, and habitat preferences of the 12 indigenous, resident species of landbirds that survive in the Vava‘u Group, Kingdom of Tonga. We surveyed 16 islands, 10 of which are previously unmentioned in ornithological literature. The islands vary in land area (0.02-96 kn?), habitat composition, elevation (20- 215 m), and distance (O-lo.1 km) from the largest island of ‘Uta Vavdu. We conducted point counts along transects on 14 of the islands, and placed each count location into one of five habitat categories. Of the 11 species of landbirds that are widespread and at least locally common, 7 (Purple-capped Fruit-Dove Ptilinopus porphyraceus, Pacific Pigeon Ducula pacijca, Common Barn-Owl Tyto alba, White-rumped Swiftlet Collocalia spodiopygia, Collared Kingfisher Halcyon chloris, Polynesian Tiiller Lalage maculosa, Polynesian Starling Aplonis tabuensis) certainly or probably occur on each of the 16 islands. One species (West Polynesian Ground-Dove Gallicolumba stairii) is extremely rare (one small population on one island). Three species that we did not record (Many-colored Fruit-Dove Ptilinopus perousii, Blue-crowned Lorikeet Vini australis, Fiji Shrikebill Clytorhynchus vitiensis) probably have been extirpated from Vava‘u. The species richness and relative abundance of landbirds on islands in Vava‘u are affected more by deforestation and other human activities than by island area, elevation, or isolation.

Since Elton highlighted the problem of biological invasions, numerous studies have established their importance in the structural evolution of natural communities, in particular insular communities. Because of their isolation, islands are regarded as natural evolution laboratories which are characteristically very fragile once the boundary is disturbed. This fragility is illustrated by the high proportion of species extinctions observed in islands: since 1600, more than 75% of monitored disappearances have been registered in islands. Invasions are not an abnormality in the evolutionary process, but an increase in their rate could lead to a dramatic homogenization of fauna and flora.

The Hanamiai archaeological site (Tahuata, Marquesas Islands) has yielded a strati ed assemblage of bird bones associated with prehistoric Polynesian artefacts, cultural features, and other faunal materials spanning an 800-year period beginning at c.ad1025–1100. The majority of the c.650 identi able bird bones are from seabirds, most species of which are extirpated on Tahuata. Indigenous landbirds (rails, pigeons, doves, parrots, king shers, warblers) are represented by 70 bones of 10 species, among which two rails, a pigeon, a dove, and three parrots no longer occur on Tahuata. The stratigraphic distribution of bird bones suggests that exploitation of indigenous species was most intense earlyintheHanamiaiculturalsequence(PhaseI;c.ad1025–1300).Byc.ad1450orbefore,thesevenextirpatedspecies of landbirds (and probably other species not recorded in the small bone sample) either had been eliminated or had become uncommon enough to elude archaeological sampling. A similar chronostratigraphic pattern of prehistoric landbird extinction has been documented for Mangaia, Cook Islands. While details of timing and taxonomy vary from island to island, an overall trend of early prehistoric depletion of birds is the rule across East Polynesia and all of Oceania.

The land snails (and semi-terrestrial molluscs) of the four islands that comprise the Pitcairn group are reviewed and the indigenous species illustrated. The strictly terrestrial molluscan faunas from the two atolls (Oeno and Ducie) are poor, like many other atolls in the Paci c. Each supports less than six species with wide geographical ranges. In contrast, the terrestrial molluscan fauna from Henderson Island, an uplifted atoll, is more diverse with at least 16 species belonging to seven families. Over half these taxa appear to be endemic, at least at the level of sub-species. Two species of semi-terrestrial molluscs have also been found on Henderson. Analyses of archaeological deposits in caves near the North Beach have revealed that at least a further six species of land snail formerly occurred on Henderson. The volcanic island of Pitcairn, the only island in the group still inhabited, supports the greatest number of terrestrial molluscs. Twenty-six species of land snail (and one semi-terrestrial pulmonate) were found living there during the recent expedition and a further three taxa were recognized amongst museum material. At least seven of these species are thought to be recent adventives and a further three are likely to have been prehistoric introductions. One Henderson (Georissa hendersoni) and three Pitcairn endemics (Paci cella lica, Sinployea pitcairnensis and Diastole tenuistriata) are formally described as new species. Some of the Pitcairn endemics occur in very restricted areas (less than a hectare) and it is important that measures should be taken to prevent the spread of invasive plants, such as rose-apple, that would threaten their survival.