California Channel Islands Research Articles

Using non-dietary gastropods in coastal shell middens to infer kelp and seagrass harvesting and paleoenvironmental conditions

Archaeologists analyzing shell middens typically focus on larger (>2 cm) mollusks to examine subsistence practices, impacts on littoral habitats, and paleoenvironmental conditions as well as a host of other natural and cultural phenomena. Small (<2 cm), non-dietary gastropods in archaeological shell middens also provide important clues regarding human resource procurement in littoral areas and coastal paleoenvironments. We present data from two sites on the California Channel Islands to demonstrate the range of information that can be gained by analyzing small gastropod shells. Identifications revealed the remains of over 4500 non-dietary small gastropods from 75 taxa. Human harvesting of marine macrophytes is suggested by the presence of 18 species that are predominantly associated with seaweeds and seagrasses. Quantification measures revealed high diversity and equitability indices, oscillating taxonomic richness, and decreasing densities through time at both sites. Likelihood ratio tests revealed differences in assemblage composition between Early Holocene and later components at one site, and demonstrated similarities in the relative composition of non-dietary shell assemblages between both sites during the Middle Holocene. Incorporating detailed studies of less conspicuous “incidental” shellfish remains in archaeological midden studies has the potential to contribute to our understanding of past human land use practices and littoral paleoecology. Our findings are applicable to archaeologists working in coastal settings around the world, as well as marine ecologists interested in intertidal paleo-habitats and kelp forest ecosystems.

&lt;b&gt;Environmental Imaginations of the California Channel Islands and Ecological Crisis in T.C. Boyle's &lt;i&gt;When the Killing's Done&lt;/i&gt;&lt;/b&gt; // Imaginaciones medioambientales de las Islas del Canal y la crisis ecológica en &lt;i&gt;When the Killing’s Done&lt;/i&gt;

This article explores T.C. Boyle’s thirteenth novel When the Killing’s Done (2011) in regard to its representation of ecological crisis and the ensuing environmental activism. In particular, it argues that the distinctly urban background and way of life of the two main protagonists, National Park Service staff member Alma Boyd Takesue and radical eco-hipster Dave LaJoy, foster environmental imaginations of the California Channel Islands that underestimate the centuries-long agricultural uses of the islands and romanticize the islands’ ecosystems as pristine ‘wilderness.’ While this perception in the tradition of the ‘American cult of wilderness’ prompts Alma and the National Park Service to reestablish a historical state of the islands’ ecosystems through the calculated extermination of invasive species, eco-activist Dave fiercely fights for the right of every non-human animal to live. Ultimately, the novel deconstructs both these endeavors to biodiversity and animal rights as highly flawed and environmentally as well as ethically inconsistent. Resumen Este artículo explora la decimotercera novela de T. C. Boyle con el título When the Killing’s Done (2011) en cuanto a la representación de la crisis ecológica y al consiguiente activismo ecologista. En particular, afirma que el fondo y la forma de vida claramente urbanos de los dos protagonistas principales, Alma Boyd Takesue, miembro del personal del Servicio de Parques Nacionales, y Dave LaJoy, un eco-hipster radical, fomentan imaginaciones medioambientales de las islas California Channel Islands que subestiman los largos siglos de uso agrícola de las islas e idealizan los ecosistemas de las islas como ‘naturaleza virgen.’ Mientras esta percepción en la tradición del “culto americano de naturaleza virgen” anima a Alma y al Servicio de Parques Nacionales a restablecer un estado histórico de los ecosistemas de las islas a través del exterminio deliberado de especies invasoras, el eco-activista Dave lucha decididamente por el derecho de todos los animales no-humanos a vivir. En última instancia, la novela deconstruye ambos esfuerzos por la biodiversidad y los derechos de los animales como muy imperfectos e inconsistentes tanto ambiental como éticamente.

Sourcing archaeological asphaltum (bitumen) from the California Channel Islands to submarine seeps

Asphaltum, often referred to as bitumen, is a naturally occurring form of petroleum that was used by ancient cultures for thousands of years. Asphaltum deposits are found throughout the world and occur both on land and submerged under water. Ethnohistoric accounts of native Californians suggest that asphaltum from terrestrial seeps was shaped by hand into cakes and traded throughout Southern California and was the only grade of asphaltum used to manufacture plank-canoes. While there are no terrestrial seeps on the California Channel Islands, drift asphaltum exuded from submarine seeps can frequently be found washed up on the shore. It remains unclear to what extent prehistoric island populations relied on this drift asphaltum and whether or not they acquired terrestrial asphaltum through trade. This study combines gas chromatography/mass spectrometry (GC/MS) and liquid chromatography coupled with carbon isotopic analysis in an effort to identify the sources of six archaeological bituminous mixtures from San Nicolas and San Miguel islands. We compare the archaeological asphaltum to four modern samples collected from marine tarballs and a mainland terrestrial seep. Further, we compare our results to a USGS chemometric database to determine if our archaeological samples match extant sources. Our results show that prehistoric peoples on the Channel Islands utilized drift asphaltum from submarine seeps in a variety of technological applications throughout the Holocene. The methods used in our study are globally applicable and can be used to address a variety of broad anthropological questions.

Island Specialists: Shared Flora of the Alta and Baja California Pacific Islands

The floristic connection between the mediterranean region of Baja California and the Pacific islands of Alta and Baja California provides insight into the history and origin of the California Floristic Province. We present updated species lists for all California Floristic Province islands and demonstrate the disjunct distributions of 26 taxa between the Baja California and the California Channel Islands. These 26 plant taxa are found among the 16 Pacific islands without occurring on the intervening mainland of Alta California. Separate species lists for each island group (8 California Channel Islands and 8 Baja California Islands) were compiled. These lists were compared to the mainland California flora to identify species that occur on the California Islands and either the Baja California Pacific Islands or the mediterranean region of the Baja California Peninsula, but not the mainland of Alta California. This first compilation of the flora of the Baja California Islands and nomenclatural updates for the Channel Islands provide a platform for future research and conservation planning.

Stand Structure and Acorn Production of the Island Scrub Oak (Quercus pacifica)

Island scrub oak (Quercus pacifica), a keystone chaparral species on Santa Rosa, Santa Cruz, and Santa Catalina islands, provides habitat for a diverse assemblage of plant and animal species. The restoration of oak habitat is a management priority, but little is known about Q. pacifica stand structure and acorn production, 2 parameters that are important in the species' recovery. To investigate whether species interactions and abiotic conditions have an effect on stand structure and acorn production, we sampled within-stand densities, tree sizes, and acorns in the 3 island populations that have been exposed to different herbivores, seed predators, and climate conditions. Stand densities varied more within than between islands; but Santa Rosa, the coldest of the 3 islands, had smaller trees with smaller acorns than the other 2 islands. To quantify the temporal and spatial variation in acorn production on Santa Cruz Island, we conducted acorn counts at 2 spatial scales: (1) an island-wide survey of 200 trees along the east—west axis of the island (2008–2012) and (2) small-scale surveys within three 100-ha study plots (150 trees; 2009–2012). Acorn production varied strongly, both temporally and spatially, with little temporal synchrony and spatial autocorrelation. Trees at higher elevations produced more acorns, but the roles of temperature and precipitation were unclear in this relatively short study. To increase our understanding of the drivers of Q. pacifica acorn production, we propose that annual oak surveys be incorporated into a long-term monitoring program across the California Channel Islands.

Restoration of a Coastal Wetland at Prisoners Harbor, Santa Cruz Island, Channel Islands National Park, California

Abstract. Prisoners Harbor of Santa Cruz Island, California, was historically the site of a 4.86-ha coastal wetland and riparian system—the largest on the California Channel Islands. The site was occupied by native people for 3000 years until the 1830s. During the late 1800s, ranchers filled about half of the wetland area to build livestock corrals and other facilities. They also rerouted the main stream channel, Canada del Puerto, and built a stone wall and earthen berm along its west bank. This disconnected the stream from its floodplain and inadvertently caused erosion of a Native American archeological site. The National Park Service developed a wetland and riparian restoration design for Prisoners Harbor based on topographic and hydrologic analyses and on relationships between vegetation community and depth to water table estimated from neighboring reference wetlands. In 2011, Channel Islands National Park and The Nature Conservancy restored 1.25 ha of coastal wetland and reconnected the stream to it...

Genetic variation among mainland and island populations of a native perennial grass used in restoration.

Genetic marker studies can assist restoration practice through selection of seed sources that conserve historical levels of gene diversity and population genetic differentiation. We examined genetic variation and structure within and among mainland and island populations of Elymus glaucus, a perennial bunchgrass species native to western North American grasslands that is targeted for grassland restoration. Island populations of E. glaucus represent sensitive sites and potentially distinctive seed sources for reintroduction, and little is known of their genetic composition. Genetic diversity and structure were estimated using amplified fragment length polymorphism markers for 21 populations and 416 individuals distributed across two coastal California mainland locations and three California Channel Islands. Eight primer combinations resulted in 166 markers, of which 165 (99.4 %) were polymorphic. The number of polymorphic bands was significantly greater among mainland populations relative to island sites, and locally common alleles were present for each sampled island and mainland location. Population structure was high (62.9 %), with most variation (55.8 %) distributed among populations, 7.1 % between mainland and island locations, and the remainder (37.1 %) within populations. Isolation by distance was only apparent among islands. Using marker data to recommend appropriate seed sources for restoration, E. glaucus seeds are best derived within islands with collections representing a large number of individuals from matching environments. Given the limited gene flow and prior evidence of adaptive divergence among populations of this species, regional collections are recommended in all cases to maintain diversity and to avoid long-distance introductions of highly differentiated plant material.

Contributions to an Arthropod Inventory of Santa Cruz Island, California

Arthropods have been understudied on Santa Cruz Island, resulting in an incomplete understanding of these diverse and ecologically important members of island ecosystems. To enhance the current understanding of Santa Cruz Island biodiversity, we sampled arthropods in 2 native plant habitats: island scrub oak (Quercus pacifica) woodland and patches of island morning glory (Calystegia macrostegia ssp. macrostegia). We used 4 standardized sampling techniques to sample arthropods in 16 Q. pacifica woodland plots. We sampled arthropods associated with C. macrostegia by pan trapping within 1 m of blooming morning glory individuals. In total, we sampled over 18,000 arthropod specimens, sorted the specimens to morphotypes by order, and had taxonomic specialists identify 10 orders to the narrowest possible identification (n = 458 total species or morphotypes). The taxonomic distribution of our identified specimens is as follows: 1 species of Scorpiones, 5 morphospecies of Pseudoscorpiones, 74 species of Araneae, 4 species of Orthoptera, 10 species of Psocodea, 10 species of Hemiptera, 1 species of Neuroptera, 60 species of Coleoptera, 8 species of Lepidoptera, and 42 species of Hymenoptera (Formicidae and Apoidea). Of these, 62 species represent newly recorded arthropod species on Santa Cruz Island. The diversity of our collections within the Quercus pacifica and Calystegia macrostegia habitats, the deficiency of current knowledge of Channel Island arthropods, and the fundamental role of arthropods in island ecosystems emphasize the need for a more comprehensive arthropod inventory across the California Channel Islands.

The Contributions of Donald Lee Johnson to Understanding the Quaternary Geologic and Biogeographic History of the California Channel Islands

Over a span of 50 years, native Californian Donald Lee Johnson made a number of memorable contributions to our understanding of the California Channel Islands. Among these are (1) recognizing that carbonate dunes, often cemented into eolianite and derived from offshore shelf sediments during lowered sea level, are markers of glacial periods on the Channel Islands; (2) identifying beach rock on the Channel Islands as the northernmost occurrence of this feature on the Pacific Coast of North America; (3) recognizing of the role of human activities in historic landscape modification; (4) identifying both the biogenic and pedogenic origins of caliche “ghost forests” and laminar calcrete forms on the Channel Islands; (5) providing the first soil maps of several of the islands, showing diverse pathways of pedogenesis; (6) pointing out the importance of fire in Quaternary landscape history on the Channel Islands, based on detailed stratigraphic studies; and (7), perhaps his greatest contribution, clarifying the origin of Pleistocene pygmy mammoths on the Channel Islands, due not to imagined ancient land bridges, but rather the superb swimming abilities of proboscideans combined with lowered sea level, favorable paleowinds, and an attractive paleovegetation on the Channel Islands. Don was a classic natural historian in the great tradition of Charles Darwin and George Gaylord Simpson, his role models. Don's work will remain important and useful for many years and is an inspiration to those researching the California Channel Islands today.

Reintroduction of Historically Extirpated Taxa on the California Channel Islands

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 systems and could be adapted to develop conservation strategies for species that may be candidates for assisted colonization in the face of climate change.

Evidence of Repeated Wildfires Prior to Human Occupation on San Nicolas Island, California

Understanding how early humans on the California Channel Islands might have changed local regimes requires a baseline knowledge of the frequency of natural wildfires on the islands prior to human occupation. A sedimentary sequence that was recently discovered in a small canyon on San Nicolas Island contains evidence of at least 24 burn events that date to between ~37 and 25 ka (thousands of calibrated 14C years before present), well before humans entered North America. The evidence includes abundant macroscopic charcoal, blackened sediments, and dis- crete packages of oxidized, reddish-brown sediments that are similar in appearance to sedimentary features called fire areas on Santa Rosa Island and elsewhere. Massive fine-grained sediments that contain the burn evidence are inter- preted as sheetwash deposits and are interbedded with coarse-grained, clast-supported alluvial sediments and matrix- supported sands, pebbles, and cobbles that represent localized debris flows. These sedimentary sequences suggest that the catchment area above our study site underwent multiple cycles of relative quiescence that were interrupted by and followed by slope instability and mass wasting events. Our 14C-based chronology dates these cycles to well before the arrival of humans on the Channel Islands and shows that natural wildfires occurred here, at a minimum, every 300-500 years prior to human occupation.

On the Origins of the Insect Fauna of California's Channel Islands: A Comparative Phylogeographic Study of Island Beetles

California's 8 Channel Islands host a large diversity of insects, the vast majority of which are shared with mainland southern California. The existence of a small number of recognized endemic species, however, suggest that, for some lineages, the islands are isolated enough to have permitted significant differentiation. Here we investigate the phylogeographic relationships of 4 beetle species (Thinopinus pictus, Hadrotes crassus, Hypocaccus lucidulus, and Nyctoporis carinata): all occurring on the mainland and on multiple (up to 6) Channel Islands. Sequences of the cytochrome oxidase I mitochondrial gene (and, for one species, an intron in the nuclear guftagu gene) are analyzed by Bayesian, haplotype network, and population genetic methods to examine relationships and gene flow among island and mainland populations. In no instances were all island populations resolved to be monophyletic, and northern (Santa Cruz, Santa Rosa, San Miguel) and southern (San Nicolas, San Clemente, Santa Catalina) island groups generally showed separate relationships to the mainland. Northern island populations of Hy. lucidulus were also found to be closely related to those on the southern island of San Nicolas. Populations on San Clemente and Santa Catalina islands did not show close relationships to each other or to San Nicolas Island populations in any species. San Clemente and especially San Nicolas islands hosted disproportionately high levels of diversity in all species examined. This study suggests that the Channel Islands do not function as a biogeographical unit and that several of the islands exhibit levels of diversity comparable to, or even exceeding, similarly sampled populations on the mainland. Thus, as an insular refuge from southern Californian development, the Channel Islands constitute a center of high conservation importance.

Changes in Vegetation and Biological Soil Crust Communities on Sand Dunes Stabilizing after a Century of Grazing on San Miguel Island, Channel Islands National Park, California

San Miguel Island is the westernmost of the California Channel Islands and one of the windiest areas on the west coast of North America. The majority of the island is covered by coastal sand dunes, which were stripped of vegetation and subsequently mobilized due to droughts and sheep ranching during the late 19th century and early 20th century. Since the removal of grazing animals, vegetation and biological soil crusts have once again stabilized many of the island's dunes. In this study, historical aerial photographs and field surveys were used to develop a chronosequence of the pattern of change in vegetation communities and biological soil crust levels of development (LOD) along a gradient of dune stabilization. Historical aerial photographs from 1929, 1954, 1977, and 2009 were georeferenced and used to delineate changes in vegetation canopy cover and active (unvegetated) dune extent among 5 historical periods (pre-1929, 1929–1954, 1954–1977, 1977–2009, and 2009–2011). During fieldwork, vegetation and biological soil crust communities were mapped along transects distributed throughout San Miguel Island's central dune field on land forms that had stabilized during the 5 time periods of interest. Analyses in a geographic information system (GIS) quantified the pattern of changes that vegetation and biological soil crust communities have exhibited on the San Miguel Island dunes over the past 80 years. Results revealed that a continuing increase in total vegetation cover and a complex pattern of change in vegetation communities have taken place on the San Miguel Island dunes since the removal of grazing animals. The highly specialized native vascular vegetation (sea rocket, dunedelion, beach-bur, and locoweed) are the pioneer stabilizers of the dunes. This pioneer community is replaced in later stages by communities that are dominated by native shrubs (coastal goldenbush, silver lupine, coyote-brush, and giant coreopsis), with apparently overlapping or cyclical succession pathways. Many of the dunes that have been stabilized the longest (since before 1929) are dominated by exotic grasses. Stands of biological soil crusts (cyanobacteria) are found only on dunes where vascular vegetation is already present. Biological soil crusts are not found on dunes exhibiting a closed vascular plant canopy, which may indicate that the role of soil crusts in dune stabilization on the island is transitory. Particle-size analyses of soil samples from the study area reveal that higher biological soil crust LOD is positively correlated with increasing fine grain content. The findings indicate that changes in vegetation communities may be the most rapid at earlier and later stages of dune stabilization and that regular monitoring of dunes may help to identify the interactions between vegetation and soil crusts, as well as the potential transitions between native and exotic plant communities.

Argentine Ant Management in Conservation Areas: Results of a Pilot Study

Argentine ants (Linepithema humile) have invaded many areas of conservation concern, including half of the California Channel Islands. On Santa Cruz Island, the species has invaded approximately 2% of the island, and the infestations are expanding. Argentine ants displace many other invertebrates, and their expansion throughout the island could lead to the extirpation of native invertebrate species and the disruption of key ecological processes (e.g., plant-pollinator interactions and seed dispersal). We describe a treatment protocol to manage or eliminate Argentine ants on Santa Cruz Island developed by The Nature Conservancy and the National Park Service, in collaboration with academic and pest control specialists. We combined low-concentration toxicant baits with efficient dispersal methods to treat landscape-scale Argentine ant infestations in rugged terrain and dense vegetation with minimal impact to nontarget species. From May to October 2012, we applied our baiting protocol within 2 study sites, totaling 7.8 ha on Santa Cruz Island. In May 2013, one year post treatment, we observed >99% reduction in Argentine ant activity in treatment plots compared to untreated plots, using 2 different monitoring techniques. While further testing and monitoring is needed, these results suggest this protocol may be an effective tool to eliminate Argentine ant infestations from this type of habitat and terrain.

Identifying Evolutionarily Significant Units and Prioritizing Populations for Management on Islands

Islands host exceptionally high levels of endemism compared to mainland regions and are subject to disproportionately high rates of extinction and imperilment. Therefore, the protection and preservation of taxonomic units that are endemic to islands is a key component in mitigating the loss of global biodiversity. However, determining what is “endemic” on islands can be challenging. Conservation units are commonly delineated based on genetic divergence at neutral loci (e.g., genetic differentiation at microsatellite loci or reciprocal monophyly based on mitochondrial genes). Island populations of nonvolant species are expected to meet this criterion, regardless of adaptive differences, due to geographic isolation, founder effects, and small effective population sizes. We therefore argue that the delineation and management of island endemic populations should not be based on neutral genetic divergence and reciprocal monophyly alone. Instead, we recommend identifying island populations that have genetically based adaptations to their unique environments. A comprehensive framework specifically designed to delineate evolutionarily significant units (ESUs) on islands should be based on metrics of both neutral and adaptive genetic divergence. The California Channel Islands host several taxa considered to be endemic, and we highlight 2 case studies to illustrate how this framework can be applied. This approach can be applied broadly to continental islands and island archipelagos, enabling conservation practitioners to use an objective framework to prioritize units of biological diversity for management.

Landscapes of Santa Rosa Island, Channel Islands National Park, California

Abstract. Santa Rosa Island (SRI) is the second-largest of the California Channel Islands. It is one of 4 east—west aligned islands forming the northern Channel Islands chain, and one of the 5 islands in Channel Islands National Park. The landforms, and collections of landforms called landscapes, of Santa Rosa Island have been created by tectonic uplift and faulting, rising and falling sea level, landslides, erosion and deposition, floods, and droughts. Landscape features, and areas delineating groups of related features on Santa Rosa Island, are mapped, classified, and described in this paper. Notable landscapes on the island include beaches, coastal plains formed on marine terraces, sand dunes, and sand sheets. In this study, the inland physiography has been classified into 4 areas based on relief and degree of fluvial dissection. Most of the larger streams on the island occupy broad valleys that have been filled with alluvium and later incised to form steep- to vertical-walled arroyos, or barrancas, le...

Do the island biogeography predictions of MacArthur and Wilson hold when examining genetic diversity on the near mainland California Channel Islands? Examples from endemicAcmispon(Fabaceae)

The California Channel Islands are a group of eight oceanic islands located off the coast of southern California that are substantially closer to the mainland than most other well-studied island systems. The equilibrium theory of island biogeography proposed by MacArthur and Wilson posits that species diversity on an island will be positively impacted by island area and negatively impacted by isolation, which has been confirmed for the Channel Islands. In this study, we have extended MacArthur and Wilson's theory to examine how levels of genetic diversity relate to four island characteristics (island area, distance to the mainland, distance to the nearest island, plant diversity) in the endemic perennial taxa of Acmispon (Fabaceae) on the Channel Islands. We sampled two island species of Acmispon, A. argophyllus and A. dendroideus, from all islands, and mainland sister taxa for nuclear microsatellites, low-copy nuclear sequence and plastid sequence data. We found that only one measure of diversity from one genetic region (low-copy nuclear) was correlated with island area, that there was no support for a relationship between genetic diversity and distance to the mainland and that distance to the nearest island was a predictor of low-copy nuclear genetic diversity. Plant diversity was a significant predictor of plastid genetic diversity when considering all samples. We conclude that the equilibrium theory of island biogeography does not hold for measures of genetic diversity in the Channel Island endemic Acmispon based on island area and distance to the mainland. The short distance between individual islands and the mainland probably facilitates a moderate rate of mainland to island dispersal, preventing the islands from functioning as isolated biogeographic units. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 174, 289–304.

A multi‐decade time series of kelp forest community structure at the California Channel Islands

AbstractStudies of temperate rocky reef communities have added much to our understanding of ecology. However, data on these reef communities can be difficult to obtain; wind, waves, and poor underwater visibility often prevent research diving, and even under the best conditions only a few hours a day can be spent underwater collecting data. Here, we present data on temperate subtidal reef communities at 33 sites, almost half of which the National Park Service has sampled annually since 1982. We present core data sets describing the population dynamics of 16 fish, 37 invertebrate, and 15 algal taxa. We include supplementary data sets documenting the size structure of key species, the relative abundance of all fish, the recruitment of selected invertebrates, and the subtidal water temperature at each site through time. Taken together, these data provide one of the most comprehensive descriptions of nearshore reef community dynamics ever assembled.

Phylogenetic relationships within the lizard clade Xantusiidae: Using trees and divergence times to address evolutionary questions at multiple levels

Xantusiidae (night lizards) is a clade of small-bodied, cryptic lizards endemic to the New World. The clade is characterized by several features that would benefit from interpretation in a phylogenetic context, including: (1) monophyletic status of extant taxa Cricosaura, Lepidophyma, and Xantusia; (2) a species endemic to Cuba (Cricosaura typica) of disputed age; (3) origins of the parthenogenetic species of Lepidophyma; (4) pronounced micro-habitat differences accompanied by distinct morphologies in both Xantusia and Lepidophyma; and (5) placement of Xantusia riversiana, the only vertebrate species endemic to the California Channel Islands, which is highly divergent from its mainland relatives. This study incorporates extensive new character data from multiple gene regions to investigate the phylogeny of Xantusiidae using the most comprehensive taxonomic sampling available to date. Parsimony and partitioned Bayesian analyses of more than 7kb of mitochondrial and nuclear sequence data from 11 loci all confirm that Xantusiidae is monophyletic, and comprises three well-supported clades: Cricosaura, Xantusia, and Lepidophyma. The Cuban endemic Cricosaura typica is well supported as the sister to all other xantusiids. Estimates of divergence time indicate that Cricosaura diverged from the (Lepidophyma+Xantusia) clade ∼81million years ago (Ma), a time frame consistent with the separation of the Antilles from North America. Our results also confirm and extend an earlier study suggesting that parthenogenesis has arisen at least twice within Lepidophyma without hybridization, that rock-crevice ecomorphs evolved numerous times (>9) within Xantusia and Lepidophyma, and that the large-bodied Channel Island endemic X. riversiana is a distinct, early lineage that may form the sister group to the small-bodied congeners of the mainland.

Capture success higher near roads for san clemente island foxes

Recently, island fox (Urocyon littoralis) populations on 4 of 6 California Channel Islands (USA) were greatly reduced by colonizing golden eagles (Aquila chrysaetos) and a suspected outbreak of disease, creating concern for subspecies on all islands. Consequently, efforts of live-trapping foxes for research, monitoring, and vaccination has increased. Despite increased trapping efforts, evaluation of factors that influence capture success has not been conducted. We examined capture success of island foxes at 85 random trapping locations on San Clemente Island during 170 trap-nights during 2006–2007. We captured 98 island foxes, and found that traps placed ≤10 m from primary roads had higher overall capture success (i.e., 1.52 times more likely to capture foxes) than traps placed at random locations throughout the study area. We found no evidence to suggest that the density of edges between land-cover types (i.e., sum length of edges per 100-m buffered area [m/m2]), nightly temperature, proportions of land-cover, or type of attractant tested (n = 3) affected capture success. All attractants captured similar proportions of sex and age classes of foxes. Our findings suggest that future trapping efforts would have the most success if conducted along roads. © 2013 The Wildlife Society.