An experimental study on the effects of an introduced parasite in Darwin’s finches

It is widely recognised that the main threats to the biota of the Galápagos Islands stem from newly introduced diseases, plants and animals. Introduced organisms may lead to the rapid extinction of naïve insular populations. Previous research on Galápagos showed that the parasitic larvae of the fly Philornis downsi occurred in virtually all nests of land bird species examined, with high nestling mortality (27% of all broods) in relation to high parasite infestation. In this study, we used an experimental approach to measure the fitness impacts of the fly larvae in two species of Darwin’s finch (Geospizinae). We created parasite-reduced nests by applying a 1% pyrethrin solution to the nest during the early nesting phase, and measured: (1) nestling growth, (2) nestling haemoglobin (Hb) concentration and (3) fledging success. A single insecticide treatment was sufficient to reduce parasite intensity to nearly zero, and revealed reduced mass gain and reduced fledging success in parasitized nests compared to parasite-reduced nests. This is the first experimental study of fitness impacts by Philornis on its host species. The results are discussed in the light of short-term protection measures for nests of rare finch species in the Galápagos archipelago.     

Modelling the effect of El Niño on the persistence of small populations: The Galápagos penguin as a case study

Small populations are vulnerable to long-term declines, even where short-term censuses indicate increasing trends in numbers. Census data for the Galápagos penguin (Spheniscus mendiculus) collected between 1970 and 2004 provide evidence that despite year-to-year population increases detected in most of the annual censuses, the strong El Niño events of 1982-83 and 1997-98 were followed by population declines of more than 60% from which the species has yet to recover. Such large declines raise concerns about the future viability of the species because the frequency and severity of El Niño events are predicted to increase. We used the simulation software VORTEX to evaluate the potential effects of El Niño on the risk of extinction of the Galápagos penguin population and its four constituent subpopulations. Weak and strong El Niño events were treated as catastrophes, with varying frequencies, which simulated past, current and future effects on the penguin population. The “Current El Niño” scenario, based on the frequency of El Niño events recorded in the Galápagos between 1965 and 2004, indicated an approximately 30% probability of extinction within the next 100 years for the penguin population. More ominously, the species may be at a greater risk if the frequency of strong El Niño episodes increases only marginally. A probability of extinction greater than 80% was predicted when the current frequency (5%) of strong El Niño events was doubled (to 10%). The probabilities of extinctions were higher for each subpopulation treated individually, ranging from 34% for Isabela and Fernandina, 64% for Bartolomé-Santiago to 78% for the smallest subpopulation on Floreana. Sensitivity analyses identified survival of penguins during El Niño events and sex ratio as influential parameters. The estimates of extinction risk may be conservative as other threats associated with increased human activities on the islands may further compromise species persistence.     

Extinction behind our backs: the possible fate of one of the Darwin’s finch species on Isla Floreana, Galápagos

Without regular monitoring a rare species may slip into extinction unnoticed. We report a possible case from the Galápagos archipelago. The warbler finch (Certhidea fusca) has not been recorded by scientists on Isla Floreana in recent years, and we have been concerned about its status. On a two-day visit to prime habitat in the breeding season of 2004 we used playback of warbler finch song and calls recorded on another island to stimulate an approach of local birds. We failed to find a single warbler finch, whereas we encountered numerous small tree finches (Camarhynchus parvulus), medium tree finches (C. pauper) and yellow warblers (Dendroica petechia). Searches in 1979, 1983, 1997 and 1999 were also unsuccessful. Our continuing failure to find any warbler finches indicates the species must be extremely rare on the island, if not actually extinct. We discuss possible reasons for their demise and draw attention to other species that could be heading in the same direction.     

Estimating the potential effects of sudden oak death on oak-dependent birds

Sudden oak death (SOD), a disease induced by the fungus-like pathogen Phytophthora ramorum, threatens to seriously reduce or eliminate several oak species endemic to the west coast of North America. We investigated how the disappearance of one of these species, coast live oak (Quercus agrifolia), may affect populations of five resident oak-affiliated California birds - acorn woodpecker (Melanerpes formicivorus), Nuttall’s woodpecker (Picoides nuttallii), Hutton’s vireo (Vireo huttoni), western scrub-jay (Aphelocoma californica), and oak titmouse (Baeolophus inornatus) - using geocoded data from Audubon Christmas Bird Counts, North American Breeding Bird Surveys, and the California Gap Analysis. Capitalizing on observed relationships between the focal bird species and both oak species diversity and areal extent, we modeled relative bird abundance while assuming complete loss of Q. agrifolia and complete, partial, or no loss of oak habitat following a disease sweep. Post-SOD projections of bird populations occurring within the range of coast live oak were on average 25-68% smaller and 13-49% more variable relative to pre-SOD estimates. SOD effects were greatest for habitats with low initial oak species diversity. Climatic SOD models predicted that the disease stands to negatively impact populations of all five focal bird species throughout 20% of California’s coast live oak habitats. This study provides the first spatially explicit insights into the potential effects of SOD on avian distribution and abundance. Results may be used to help prioritize conservation plans aimed at minimizing overall community level disturbances resulting from the disease.     

Biological effects of El Niño on the Galápagos penguin

Long-term monitoring of physical and biological parameters is essential for understanding the effects of El Niño on bird populations, particularly for small or declining populations. We examined the biological effects of El Niño activity from 1965 to 2004 using instrumental sea-surface temperatures from the Galápagos Islands and 20 years of census counts of the Galápagos penguin. Between 1965 and 2004, nine El Niño events were recorded of which two were strong and seven were weak. The two strong El Niño events of 1982-1983 and 1997-1998 were followed by crashes of 77% and 65% of the penguin population, respectively. The evidence suggests that the increased frequency of weak El Niño events limits population recovery. The 2004 penguin population is estimated to be at less than 50% of that prior to the strong 1982-1983 El Niño event. We discuss the biological effects of increased El Niño intensity and frequency within the context of a 6000-year record of El Niño influence and in the light of increasing anthropogenic threats operating after 1535, when the Archipelago was discovered by Europeans.     

Conservation action in the Galàpagos: feral pig (Sus scrofa) eradication from Santiago Island

Introduced mammals are major drivers of extinction and ecosystem change. As omnivores, feral pigs (Sus scrofa) are responsible for wholesale adverse effects on islands. Here, we report on the eradication of feral pigs from Santiago Island in the Galápagos Archipelago, Ecuador, which is the largest insular pig removal to date. Using a combination of ground hunting and poisoning, over 18,000 pigs were removed during this 30-year eradication campaign. A sustained effort, an effective poisoning campaign concurrent with the hunting program, access to animals by cutting more trails, and an intensive monitoring program all proved critical to the successful eradication. While low and fluctuating control efforts may help protect select native species, current eradication methods, limited conservation funds, and the potential negative non-target impacts of sustained control efforts all favor an intense eradication effort, rather than a sustained control program. The successful removal of pigs from Santiago Island sets a new precedent, nearly doubling the current size of a successful eradication, and is leading to more ambitious projects. However, now we must turn toward increasing eradication efficiency. Given limited conservation funds, we can no longer afford to spend decades removing introduced mammals from islands.     

Effects of feral mink removal on seabirds, waders and passerines on small islands in the Baltic Sea

We studied the effects of removing introduced American mink (Mustela vison) on the number of birds breeding on small islands in the Baltic Sea. During autumn 1992-2001 mink were removed from a 72 km² area, while mink were not removed from a 35 km² control area. Second removal (125 km²) and control areas (130 km²) were established during 1998-2001. The breeding densities of ringed plover (Charadrius hiaticula), arctic skua (Stercorarius parasiticus), arctic tern (Sterna paradisaea) and rock pipit (Anthus petrosus) increased markedly in the removal areas in comparison to the control areas. Turnstone (Arenaria interpres), common gull (Larus canus) and wheatear (Oenanthe oenanthe) also appeared to increase. Two species already extinct in one of the removal areas, razorbill (Alca torda) and black guillemot (Cepphus grylle), returned to breed in the area. Breeding densities of great black-backed gull (Larus marinus), oystercatcher (Haematopus ostralegus) and white wagtail (Motacilla alba) were unaffected. We conclude that it is possible to remove feral mink from large archipelagos with many small islands, and that mink removal increases the breeding densities of many bird species in this habitat.     

Effects of oak barrens habitat management for Karner blue butterfly (Lycaeides samuelis) on the avian community

The federally endangered Karner blue butterfly (Lycaeides samuelis) is the focal species for a conservation plan designed to create and maintain barrens habitats. We investigated whether habitat management for Karner blue butterflies influences avian community structure at Fort McCoy Military Installation in Wisconsin, USA. From 2007 through 2009 breeding bird point count and habitat characteristic data were collected at 186 sample points in five habitat types including two remnant barrens types, barrens habitat restored from woodland and managed specifically for the Karner blue butterfly, and two woodland habitat types. Although the bird community of managed barrens was not identical to the communities of remnant barrens, the Field Sparrow (Spizella pusilla), a species of conservation concern, and sparse canopy associated bird species, such as the Baltimore Oriole (Icterus galbula) and Eastern Bluebird (Sialia sialis) were predicted to occupy managed barrens and remnant barrens in similar proportions. Adjacent habitat was the most influential factor in determining the community of bird species using the managed barrens. In Wisconsin, and likely throughout the range of the Karner blue butterfly, management for the butterfly creates habitat that attracts a bird community similar to that of remnant barrens, and benefits several avian species of conservation concern. Additionally, the landscape context surrounding the managed habitat influences avian community composition. Managed barrens that are adjacent to remnant barrens, rather than adjacent to woodland habitats, have the highest potential for conserving barrens breeding birds.     

A snake in paradise: Disturbance of plant reproduction following extirpation of bird flower-visitors on Guam

The introduction of an alien top predator, the brown treesnake (Boiga irregularis), has resulted in severe losses of native vertebrate populations in Guam. Among these are important pollinators and seed dispersers. This study is a first attempt to document cascading effects on vertebrate-pollinated native plant species in Guam. We investigated flower visitation, seed set and germination in two native plants, the mangrove tree Bruguiera gymnorrhiza and the forest tree Erythrina variegata var. orientalis. Both species are bird-pollinated. Studies were conducted on two Mariana islands, Guam (with high density of snakes) and Saipan (with nearly no snakes). Visitation rates by birds were high on Saipan, but zero on Guam. Insects and lizards visited flowers to a low extent on both islands. Only lizards were potential effective pollinators. Seed set of both species were significantly higher on Saipan compared to Guam, and for B. gymnorrhiza, seedling recruitment was significantly higher on Saipan. Hence, these bird-pollinated species appear highly dependent on bird visitors for reproduction. The eradication of flower-visiting birds by the invasive treesnake thus secondarily results in broken mutualistic interactions, which may, in turn, result in a lower recruitment of native plants. Thus, the treesnake affects not only potential prey species, but its effects cascade through the entire ecosystem on Guam. Conservation actions should be directed towards an improved recruitment (artificial pollination, planting) of the affected plant species.     

Exposure to tourism reduces stress-induced corticosterone levels in Galápagos marine iguanas

Unstressed and stress-induced plasma corticosterone levels in Galápagos marine iguanas (Amblyrhynchus cristatus) were compared in animals from a site heavily exposed to tourism to animals from a site undisturbed by humans. Initial corticosterone levels not only did not differ between the two groups, but they were 50% of levels in iguanas known to be chronically stressed. These data suggest that iguanas in tourist areas are not chronically stressed. Both groups of iguanas exhibited elevated corticosterone levels after 30 min of capture and restraint, indicating that they can physiologically respond to stressful stimuli. The stress response was lower, however, at the tourist site. This result indicates that iguanas are physiologically affected by tourism, although it is presently unknown whether these changes are ultimately beneficial or harmful.     

Vegetational changes in the Galápagos Islands during the period 1966–1973

Analysis of 12 permanent sample plots established in the Galápagos showed that introduced mammals have had a destructive influence on the vegetation; closed forest and scrub have been changed into open vegetation. The plots provide information on the regeneration ability of various types of vegetation. Scalesia forest, dominated by the endemic Scalesia pedunculata Hook. f., might under certain circumstances regenerate rapidly. Miconia scrub, dominated by the endemic Miconia robinsoniana Cogn., regenerates slowly and is consequently more vulnerable to the activities of man and introduced mammals. Arid zone vegetation, characterised especially by endemic species of Opuntia, is able to regenerate, but it is still too early to estimate how the regeneration will proceed. The suggested conservation measures include a continuation of the programme for elimination or control of introduced mammals, and a stronger control with the National Park areas on inhabited islands. Financial support is needed for the Galápagos National Park Service and the Charles Darwin Research Station to continue and enlarge the activities necessary to preserve the unique wildlife of the Galápagos Islands.     

Some alien birds have as severe an impact as the most effectual alien mammals in Europe

Invasive alien species cause considerable economic and environmental damage. Nevertheless which species should be targeted first and exact control strategies are controversial matters. As no categorization of the impact of alien bird species is available so far, we adopted an impact scoring system for mammals to birds and scored the impact of the alien birds established in Europe. We investigated 26 established alien birds in Europe and compiled all known impact data for these species. The species with highest environmental impact were the Canada goose (Branta canadensis), sacred ibis (Threskiornis aethiopicus) and ruddy duck (Oxyura jamaicensis). The most severe impact on economy was exerted again by the Canada goose. Also the ring-necked parakeet (Psittacula krameri) and monk parakeet (Myiopsitta monachus) had high impact in this category. Combining these potential impact data with the current distribution generates a list of alien birds with highest actual impact. These two values can be used to prioritise preventive and control measures. In comparison to birds, mammals in general have higher potential and actual impact in Europe, but some bird species reach impact values as high as some of the worst mammal species. Still, these bird species - in contrast to mammals with high impact - are hardly targeted by control programmes. This study shows that there is no scientific reason for this. With the here presented scoring system we offer a decision tool to practitioners which supports them in finding an appropriate reaction to invasive birds.     

Pathogen exposure in endangered island fox (Urocyon littoralis) populations: Implications for conservation management

Island fox (Urocyon littoralis) populations on four California Channel Islands have declined severely since 1994. Canine distemper (CDV) was suspected to be responsible for the decline of the Santa Catalina Island fox, so knowledge of infectious disease exposure in the remaining island fox populations was urgently needed. This study reviewed previous pathogen exposure in island foxes and investigated the current threat by conducting a serologic survey of foxes on all islands and sympatric feral cats on three islands from 2001 to 2003 for antibodies against canid pathogens. Before the decline, foxes had evidence of exposure to CDV, canine adenovirus (CAV), canine parvovirus (CPV), and Toxoplasma, with exposure to these five pathogens differing greatly by island. Exposure to canine coronavirus (CCV), canine herpesvirus (CHV), and Leptospira was rare. In 2001-2003, wild-born foxes had evidence of exposure to CDV (5.2-32.8%) on 5 of 6 islands, CPV (28-100%) and CAV (4.7-100%) on five islands, and Toxoplasma gondii (2.3-15.4%) on four islands. Exposure to CCV, CHV and Leptospira was less common. Sharing of infectious agents between sympatric foxes and feral cats appeared minimal, but CDV exposure was detected in two cats on Santa Catalina Island. Domestic dogs have historically been present on the islands, but it is not known if canine diseases can be maintained in fox populations without the continual presence of dogs. Targeted vaccination programs against the most virulent pathogens and continued intensive disease surveillance may help protect the critically small remaining fox populations from disease outbreaks that could threaten the success of ongoing conservation efforts.     

Land birds of Tuamotu Archipelago, Polynesia: relative abundance and changes during the 20th century with particular reference to the critically endangered Polynesian ground-dove (Gallicolumba erythroptera)

We report relative abundances and distributions of land bird communities on eight isolated islands of the Tuamotu Archipelago (Polynesia, South Pacific Ocean) during two 21-day expeditions in 1999. The selection of islands was based on the historical range of the Polynesian ground-dove (Gallicolumba erythroptera), in the hope of finding populations of this critically endangered species. Data were also collected on the Tuamotu sandpiper Prosobonia cancellata, the Atoll Fruit-dove Ptilinopus coralensis, the Tuamotu reed-warbler Acrocephalus atyphus, the Spotless Crake Porzana tabuensis and the Bristle-thighed Curlew Numenius tahitiensis, and on introduced predators (cats, rats, pigs and dogs). None of the five land-bird species recorded previously, in 1922 and 1974, has completely disappeared, but ranges of several species have contracted. Only one population of G. erythroptera erythroptera was found and it is the only population known for this species today. Our data also raise particular concern for the future of the Tuamotu sandpiper.     

Facilitating the evolution of resistance to avian malaria in Hawaiian birds

Research has shown that avian malaria plays an important role in limiting the distribution and population sizes of many Hawaiian birds, and that projected climate change is likely to eliminate most disease-free habitat in Hawai’i in the next century. I used a modeling approach, parameterized with demographic data from the literature and the field, to examine alternate management scenarios for the conservation of native Hawaiian birds. I examined the feasibility of using management in the form of rodent control to facilitate the evolution of resistance to malaria by increasing the survival and reproduction of native birds. Analysis of demographic data from seven native species, Akepa (Loxops coccineus), ‘Akohekohe (Palmeria dolei), Elepaio (Chasiempis sandwichensis), Hawai’i’amakihi (Hemignathus virens), Hawai’i creeper (Oreomystis mana), Omao (Myadestes obscurus), and Palila (Loxioides bailleui), suggest that differences in life history cause some species to be more susceptible to local extinctions from the transmission of malaria. Modeling results demonstrated that rodent control at middle, but not high, elevations can facilitate the evolution of resistance to malaria in several species of Hawaiian birds. Advocating a management approach that encourages evolutionary change in endangered species contrasts with the traditional conservation paradigm but it may be the best strategy to reduce the impacts of one of the multiple stressors that have devastated the native bird community of Hawai’i.     

Effects of the introduced parasite Philornis downsi on nestling growth and mortality in the medium ground finch (Geospiza fortis)

Invasive species have the potential to detrimentally affect native ecosystems by out competing or directly preying upon native organisms, and have been implicated in the extinction of endemic populations. One potentially devastating introduced species in the Galápagos Islands is the parasitic fly Philornis downsi. As larvae, P. downsi parasitize nestling birds and have been associated with high nestling mortality and reduced growth rates. Here I document nestling growth and mortality in a bimodal population of the medium ground finch, Geospiza fortis. Observations were conducted over three years, and under variable ecological conditions. Annual parasite prevalence in nests ranged from 64% to 98%, and nestling mortality in nests with parasites ranged from 16% to 37%. Parasite load and parasite load per nestling follow a skewed distribution with many nests having relatively few parasites, and few nest having many. Parasite load, however, was not correlated with onset of breeding, clutch size, the number of nestlings, nestling survival or fledgling success. Parasite load per nestling, on the other hand, was correlated with clutch initiation date and the proportion of nestlings that died in parasitized nests. Neither nestling size nor growth rate differed between parasitized and unparasitized nests. In addition, male and female beak morphology was not correlated with parasite load, breeding variables or nestling survival. Thus, while overall mortality due to parasitism is high, ecological conditions and possible host defenses may potentially counter some of the detrimental affects of P. downsi on nestling size and growth. These results taken together suggest that parasitism of P. downsi larvae on nestling G. fortis has the potential to lead to large population declines.     

A multi-scale analysis of species-environment relationships: breeding birds in a pitch pine-scrub oak (Pinus rigida-Quercus ilicifolia) community

Analyses of species-environment relationships are critically needed to guide conservation of many declining species. Comprehensive investigations of these relationships must incorporate environmental variables at multiple spatial scales since species responses to the environment vary with the scale of observation. We used partial canonical correspondence analysis to associate a bird assemblage in a threatened pitch pine-scrub oak (Pinus rigida-Quercus ilicifolia) community in Plymouth County, Massachusetts, USA, with plot, patch, and landscape level variables. The first level of analysis partitioned the amount of variance in the bird community explained by plot, patch, and landscape factors from that explained by spatial autocorrelation. The second level partitioned the amount of variance explained by plot, patch, and landscape factors alone and in combination. All three levels of environmental variables together accounted for 43% of the variance in the species data and only 5% of the variance was explainable by spatial factors alone. Landscape level factors accounted for a slightly larger amount of the explained variation (12%) than plot (11%) or patch (8%) level factors. We also examined the cumulative fit of each species to the plot, patch, and landscape partial models. Nine species of regional and/or national conservation concern had distributions that fit one model considerably better than the others. The Great Crested Flycatcher (Myiarchus crinitus) and Black-and-white Warbler (Mniotilta varia) were predominantly associated with plot level factors; the Whip-poor-will (Caprimulgus vociferus) was predominantly associated with patch level factors; and the Purple Finch (Carpodacus purpureus), Gray Catbird (Dumetella carolinensis), Scarlet Tanager (Piranga olivacea), Ovenbird (Seiurus aurocapillus), Brown Thrasher (Toxostoma rufum), and Eastern Kingbird (Tyrannus tyrannus) were predominantly associated with landscape level factors. This study suggests that focusing conservation efforts at the landscape level would provide the most effective protection for the largest number of sensitive species.     

Regional scale effects of human density and forest disturbance on large-bodied vertebrates throughout the Yucatán Peninsula, Mexico

The occupancy probability of 35 large-bodied bird and mammal species was examined in relation to patch- and landscape-scale habitat and disturbance variables in 147 forest patches distributed throughout the Mexican Yucatán Peninsula. Occupancy was assessed on the basis of interviews with local informants. The most important predictors of vertebrate species richness, composition, and patch occupancy were human population density and the extent and quality of forest cover. Most forest species responded positively to forest extent, while felids in particular were sensitive to human population density. However, the effects of human density on patch occupancy operated at extremely local scales. Effects were stronger at a smaller grain size, offering optimistic prospects for conservation strategies that incorporate human population effects. Three arboreal frugivores (Ateles geoffroyi, Alouatta pigra, and Ramphastos sulfuratus) were strongly associated with total basal area of trees bearing fleshy fruits. The degree of hunting pressure was not related to human population density, and affected the occupancy probability of three game species, two of which (Mazama spp., Crax rubra) are among the most preferred prey across the Yucatán Peninsula. Levels of patch occupancy across this region varied considerably among species, and were best explained by body size and degree of forest habitat specificity, large-bodied species and habitat specialists being the most vulnerable. This study provides a quantitative assessment of the conservation potential of large vertebrates in Mesoamerica and identifies disturbance-sensitive species. This can inform regional-scale conservation planning at a time when low deforestation in parts of the Yucatán Peninsula still provides a narrow window of conservation opportunity given the rapid human population growth.     

Identifying the characteristics of organic soil amendments that suppress soilborne plant diseases

Application of organic amendments has been proposed as a strategy for the management of diseases caused by soilborne pathogens. However, inconsistent results seriously hinder their practical use. In this work we use an extensive data set of 2423 studies derived from 252 papers to explore this strategy. First, we assess the capability of a specific organic amendment to control different diseases; second, we investigate the influence of organic matter (OM) decomposition on disease suppressiveness; and third, we search for physical, chemical and biological parameters able to identify suppressive OM. OM was found to be consistently suppressive to different pathogens in only a few studies where a limited number of pathogens were tested. In the majority of studies a material suppressive to a pathogen was ineffective or even conducive to other pathogens, suggesting that OM suppressiveness is often pathogen-specific. OM decomposition in many studies (73%, n = 426) emerged as a crucial process affecting suppressiveness. During decomposition, disease suppression either increased, decreased, was unchanged or showed more complex responses, such as ‘hump-shaped’ dynamics. Peat suppressiveness generally decreased during decomposition, while responses of composts and crop residues were more complex. However, due to the many interactions of contributing factors (OM quality, microbial community composition, pathosystem tested and decomposition time), it was difficult to identify specific predictors of disease suppression. Among the 81 parameters analysed, only some of the 643 correlations showed a consistent relationship with disease suppression. The response of pathogen populations to OM amendments was a reliable feature only for some organic matter types (e.g. crop residues and organic wastes with C-to-N ratio lower than ∼15) and for pathogens with a limited saprophytic ability (e.g., Thielaviopsis basicola and Verticillium dahliae). Instead, population responses of the pathogenic fungi Phytophthora spp., Rhizoctonia solani and Pythium spp. appeared unrelated to disease suppression. Overall, enzymatic and microbiological parameters, rather than chemical ones, were much more informative for predicting suppressiveness. The most useful features were FDA activity, substrate respiration, microbial biomass, total culturable bacteria, fluorescent pseudomonads and Trichoderma populations. We conclude that the integration of different parameters (e.g. FDA hydrolysis and chemical composition by ¹³C NMR) may be a promising approach for identification of suppressive amendments.     

Vulnerability of ground-nesting waterbirds to predation by invasive American mink in the Cape Horn Biosphere Reserve, Chile

Biological invasions constitute one of the most important threats to biodiversity. This is especially true for “naïve” birds that have evolved in the absence of terrestrial predators in island ecosystems. The American mink (Mustela vison) has recently established a feral population on Navarino Island (55°S), southern Chile, where it represents a new guild of terrestrial mammal predators. We investigated the impact of mink on ground-nesting coastal waterbirds with the aim of deriving a vulnerability profile for birds as a function of different breeding strategies, habitat, and nest characteristics. We compared rates of nest survival and mink predation on 102 nests of solitary nesting species (Chloephaga picta, Tachyeres pteneres), on 361 nests of colonial birds (Larus dominicanus, Larus scoresbii, Sterna hirundinacea), and on 558 artificial nests. We calculated relative mink and bird densities at all nest sites. Nests of colonial species showed the highest nest survival probabilities (67-84%) and no predation by mink. Nest survival rates for solitary nesting species were lower (5-20%) and mink predation rates higher (10-44%). Discriminant analyses revealed that mink preyed upon artificial nests mainly at shores with rocky outcroppings where mink were abundant. High nest concealment increased the probability for predation by mink. Conservation planning should consider that invasive mink might severely affect the reproduction success of bird species with the following characteristics: solitary nesting, nesting habitat at rocky outcrop shores, and concealed nests. We recommend that work starts immediately to control the mink population with a priority in the nesting habitats of vulnerable endemic waterbirds.