We evaluated patterns of herbivory and predation/scavenging by a small mammal, the arctic ground squirrel (Urocitellus parryii), as an indicator of biological diversity, vegetation structure, and ecological integrity on two contrasting islands in the vast and remote Alaska Maritime National Wildlife Refuge. Using DNA metabarcoding techniques, we assessed the taxonomic composition of vertebrates, vascular plants, and bryophytes at family and growth form levels in arctic ground squirrel fecal samples collected on the ecologically intact island of Chowiet, which supports diverse seabird and vegetation communities, and the degraded island of Chirikof, which has incurred centuries of disturbance from introduced arctic fox (Vulpes lagopus) and cattle (Bos taurus taurus). We also evaluated whether fecal samples collected across the growing season (May—August) could act as indicators of herbivore-plant phenology. We did not detect any vertebrate taxa, however, observed herbivory patterns closely matched known differences in island plant diversity based on independent surveys. Diets from the ecologically intact island exhibited higher taxonomic richness, greater evenness, and higher shrub content than the ecologically degraded island, which is a grass- and forb-dominated ecosystem. On Chowiet Island, diets changed seasonally, likely in response to changing availability, nutritional quality, and toxin content associated with primary production. Small mammal diet served as an effective indicator of plant diversity, vegetation structure, and ecological integrity when compared against known composition and status of these remote island ecosystems. Non-invasive fecal sampling and dietary analyses using genetic techniques may provide a useful strategy for monitoring biological diversity, particularly in remote areas where widespread intensive sampling is unfeasible.

The intentional and unintentional movement of plants and animals by humans has transformed ecosystems and landscapes globally. Assessing when and how a species was introduced are central to managing these transformed landscapes, particularly in island environments. In the Gulf of Alaska, there is considerable interest in the history of mammal introductions and rehabilitating Gulf of Alaska island environments by eradicating mammals classified as invasive species. The Arctic ground squirrel (Urocitellus parryii) is of concern because it affects vegetation and seabirds on Gulf of Alaska islands. This animal is assumed to have been introduced by historic settlers; however, ground squirrel remains in the prehistoric archaeological record of Chirikof Island, Alaska, challenge this timeline and suggest they colonized the islands long ago. We used 3 lines of evidence to address this problem: direct radiocarbon dating of archaeological squirrel remains; evidence of prehistoric human use of squirrels; and ancient DNA analysis of dated squirrel remains. Chirikof squirrels dated to at least 2000 years ago, and cut marks on squirrel bones suggested prehistoric use by people. Ancient squirrels also shared a mitochondrial haplotype with modern Chirikof squirrels. These results suggest that squirrels have been on Chirikof longer than previously assumed and that the current population of squirrels is closely related to the ancient population. Thus, it appears ground squirrels are not a recent, human-mediated introduction and may have colonized the island via a natural dispersal event or an ancient human translocation.

More than US$21 billion is spent annually on biodiversity conservation. Despite their importance for preventing or slowing extinctions and preserving biodiversity, conservation interventions are rarely assessed systematically for their global impact. Islands house a disproportionately higher amount of biodiversity compared with mainlands, much of which is highly threatened with extinction. Indeed, island species make up nearly two-thirds of recent extinctions. Islands therefore are critical targets of conservation. We used an extensive literature and database review paired with expert interviews to estimate the global benefits of an increasingly used conservation action to stem biodiversity loss: eradication of invasive mammals on islands. We found 236 native terrestrial insular faunal species (596 populations) that benefitted through positive demographic and/or distributional responses from 251 eradications of invasive mammals on 181 islands. Seven native species (eight populations) were negatively impacted by invasive mammal eradication. Four threatened species had their International Union for the Conservation of Nature (IUCN) Red List extinction-risk categories reduced as a direct result of invasive mammal eradication, and no species moved to a higher extinction-risk category. We predict that 107 highly threatened birds, mammals, and reptiles on the IUCN Red List-6% of all these highly threatened species-likely have benefitted from invasive mammal eradications on islands. Because monitoring of eradication outcomes is sporadic and limited, the impacts of global eradications are likely greater than we report here. Our results highlight the importance of invasive mammal eradication on islands for protecting the world's most imperiled fauna.

Investigations of insular populations of Rock Ptarmigan (Lagopus muta) in Alaska over time are uncommon. We documented changes in spring density of Evermann’s Rock Ptarmigan (L. m. evermanni) on a portion of Attu Island, Alaska, from 2003 through 2009. Populations were 8.5 birds/km in 2003, decreased by approximately one-half in 2004 (3.8 birds/ km), and continued to decrease in 2005 (1.9 birds/km), 2006 (0.8 birds/km), and 2007 (0.6 birds/ km), reaching a low of 0.3 birds/km in 2009. The overall decrease from 2003 through 2007, and 2009 was approximately 97%. We conclude the most reasonable explanation for the decline was poor recruitment (90% decrease from 2003 to 2006) of young (subadult 5 yearling) to the spring population, possibly related to natural cycling of the population. We could not identify specific factors to explain the low recruitment.

We report results of a 4-year translocation effort to reestablish a breeding population of Evermann's Rock Ptarmigan (Lagopus muta evermanni) in the Near Islands group of the western Aleutian Archipelago. Habitat restoration was completed by eradication of introduced foxes from Agattu Island by 1979. We captured and moved 75 ptarmigan from Attu Island to Agattu Island during 2003-2006, and monitored 29 radio-marked females in the last 2 years of the study. We compared the demography of newly translocated birds (n = 13) with resident birds established from translocations in previous years (n = 16). Mortality risk was increased by translocation and 15% of females died within 2 weeks of release at Agattu Island. All surviving females attempted to nest but initiated clutches 8 days later in the breeding season and laid 1.5 fewer eggs per clutch than resident females. Probability of nest survival ((x) over bar +/- SE) was good for both translocated (0.72 +/- 0.17) and resident females (0.50 +/- 0.16), and renests were rare. Probability of brood survival was higher among translocated (0.85 +/- 0.14) than resident females (0.25 +/- 0.12), partly as a result of inclement weather in 2006. Fecundity, estimated as female fledglings per breeding female, was relatively low for both translocated (0.9 +/- 0.3) and resident females (0.3 +/- 0.2). No mortalities occurred among radio-marked female ptarmigan during the 10-week breeding season, and the probability of annual survival for females in 2005-2006 was between 0.38 and 0.75. Translocations were successful because females survived, successfully nested, and recruited offspring during the establishment stage. Post-release monitoring provided useful demographic data in this study and should be a key component of translocation programs for wildlife restoration. Future population surveys and additional translocations may be required to ensure long-term viability of the reintroduced population of ptarmigan at Agattu Island. Received 31 July 2008. Accepted 16 July 2009.

Author(s): Ebbert, Steve; Burek-Huntington, Kathy | Abstract: To eradicate invasive Norway rats, an aerial broadcast of the rodenticide Brodifacoum-25W Conservation was conducted on 2,777-ha Rat Island, within the Aleutian Islands Unit of Alaska Maritime National Wildlife Refuge, between 29 September and 5 October 2008. During subsequent visits to Rat Island (in spring and fall 2009) to check for evidence of remaining rats and to look for evidence of nontarget mortality, personnel found an unexpectedly high number of dead birds: more than 420 carcasses, mostly glaucous-winged gulls and bald eagles, but also included 24 other species. Some carcasses had tissue suitable for analysis and were collected. Seventy bird carcasses were necropsied and cause of death was determined for 50 birds; 45 died of brodifacoum toxicosis. Necropsy determined almost all gulls and eagles had extensive hemorrhaging, consistent with brodifacoum poisoning. All eagles and all but 1 gull tested positive for brodifacoum residues. Positive tests for brodifacoum also were recorded for single specimens of emperor goose, northern fulmar, pelagic cormorant, peregrine falcon, rock sandpiper, and gray-crowned rosy finch. Two Lapland longspurs tested positive for exposure to brodifacoum. Nontarget bird mortality from brodifacoum exposure at Rat Island was higher than predicted in the Environmental Assessment.

We lack critical information for oceanic archipelagos worldwide related to the origin and status of insular faunas. In southwestern Alaska, in particular, a need exists to tease apart whether specific insular populations are naturally occurring or are the result of exotic introductions by humans. We analyzed variation in mitochondrial sequences of the cytochrome-b gene and 8 nuclear microsatellite loci across 215 individuals representing 17 populations (12 insular) to refine our understanding of the history of the previously identified Southwest clade of arctic ground squirrels (Spermophilus parryii). We found significant geographic structure that suggests long-term isolation and diversification (Ushugat Island and Cold Bay), but we also documented closely related populations that are likely the result of human-mediated introductions. The latter instances (Kavalga and Unalaska islands) corroborate reports from early Alaska explorers. DOI: 10.1644/09-MAMM-A386.1.