Santa Catalina Island Research Articles

Enhancing biodiversity: historical ecology and biogeography of the Santa Catalina Island ground squirrel, Otospermophilus beecheyi nesioticus.

People have influenced Earth's biodiversity for millennia, including numerous introductions of domestic and wild species to islands. Here, we explore the origins and ecology of the Santa Catalina Island ground squirrel (SCIGS; Otospermophilus beecheyi nesioticus), one of only five endemic terrestrial mammals found on California's Santa Catalina Island. We synthesized all records of archaeological/palaeontological SCIGS, conducted radiocarbon dating and stable isotope analysis of the potentially earliest SCIGS remains and performed genetic analysis of modern SCIGS. Squirrels were not identified in island palaeontological deposits, but at least 12 island archaeological sites contain SCIGS bones, including some that are butchered or burned. All directly dated SCIGS bones are Late Holocene in age and younger than approximately 1290 cal BP. The first mitochondrial genome for modern Otospermophilus beecheyi and 15 modern SCIGS mitogenomes document at least one introduction of squirrels. Stable isotope data indicate variable SCIGS diets and potential subsidies from marine environments to terrestrial plants consumed by some individuals. We cannot rule out a natural overwater dispersal, but the earliest SCIGS remains post-date the earliest evidence for people by several millennia and, along with other lines of evidence, support a human-assisted translocation of squirrels during the Late Holocene. These data illustrate the important role of Indigenous people in shaping and enhancing island biodiversity and ecology around the world.

Hurricanes, reconstruction, and resistance: thinking through vulnerability in the Caribbean.

This paper critically analyses events that surrounded the reconstruction of the Colombian archipelago of San Andrés, Providencia, and Santa Catalina islands after Hurricane Iota struck in 2020. Discussing the historical-structural and conjunctural dimensions within which the archipelago's history, various hurricanes, and reconstructions must be set, this paper draws on two theoretical conversations from Latin American and Caribbean critical thought and the critical humanitarian field that understand humanitarian governance as an 'arena of dispute'. Through mainly archival research of different sources, this paper assesses reconstruction and what it laid bare: structural vulnerability largely produced by the long lasting coloniality of power. In addition, it describes the active mediations and negotiations and the plethora of actions and repertoires in response to these centralised plans. Ultimately, we offer a vision whereby what is negotiated concerns not only the priorities and directions of the reconstruction, but also the design of a different future for the islands.

Effects of urban eutrophication on pelagic habitat capacity in the Southern California Bight

Land-based nutrient inputs to the ocean have been linked to increased coastal productivity, subsurface acidification and O2 loss, even in upwelling systems like the Southern California Bight. However, whether eutrophication alters the [environment’s] capacity to support key taxa has yet to be evaluated for this region. Here, we assess the impact of land-based nutrient inputs on the availability of aerobic and calcifying habitat for key pelagic taxa using ocean model simulations. We find that acute, lethal conditions are not commonly induced in epipelagic surface waters, but that sublethal, ecologically relevant changes are pervasive. Land-based nutrient inputs reduce the potential aerobic and calcifier habitat during late summer, when viable habitat is at its seasonal minimum. A region of annually recurring habitat compression is predicted 30 – 90 km from the mainland, southeast of Santa Catalina Island. Here, both aerobic and calcifier habitat is vertically compressed by, on average, 25%, but can be as much as 60%. This effect can be traced to enhanced remineralization of organic matter that originates from the coast. These findings suggest that effects of land-based nutrients are not restricted to chemistry but extend to habitat capacity for multiple taxa of ecological and economic importance. Considerable uncertainty exists, however, in how this habitat compression translates to population-level effects.

Kelps may compensate for low nitrate availability by using regenerated forms of nitrogen, including urea and ammonium.

Nitrate, the form of nitrogen often associated with kelp growth, is typically low in summer during periods of high macroalgal growth. More ephemeral, regenerated forms of nitrogen, such as ammonium and urea, are much less studied as sources of nitrogen for kelps, despite the relatively high concentrations of regenerated nitrogen found in the Southern California Bight, where kelps are common. To assess how nitrogen uptake by kelps varies by species and nitrogen form in southern California, USA, we measured uptake rates of nitrate, ammonium, and urea by Macrocystis pyrifera and Eisenia arborea individuals from four regions characterized by differences in nitrogen availability-Orange County, San Pedro, eastern Santa Catalina Island, and western Santa Catalina Island-during the summers of 2021 and 2022. Seawater samples collected at each location showed that overall nitrogen availability was low, but ammonium and urea were often more abundant than nitrate. We also quantified the internal %nitrogen of each kelp blade collected, which was positively associated with ambient environmental nitrogen concentrations at the time of collection. We observed that both kelp species readily took up nitrate, ammonium, and urea, with M. pyrifera taking up nitrate and ammonium more efficiently than E. arborea. Urea uptake efficiency for both species increased as internal percent nitrogen decreased. Our results indicate that lesser-studied, more ephemeral forms of nitrogen can readily be taken up by these kelps, with possible upregulation of urea uptake as nitrogen availability declines.

Paradoxical Exception to Island Tameness: Increased Defensiveness in an Insular Population of Rattlesnakes.

Island tameness results largely from a lack of natural predators. Because some insular rattlesnake populations lack functional rattles, presumably the consequence of relaxed selection from reduced predation, we hypothesized that the Santa Catalina Island, California, USA, population of the southern Pacific rattlesnake (Crotalus helleri, which possesses a functional rattle), would exhibit a decrement in defensive behavior relative to their mainland counterparts. Contrary to our prediction, rattlesnakes from the island not only lacked tameness compared to mainland snakes, but instead exhibited measurably greater levels of defensiveness. Island snakes attempted to bite 4.7 times more frequently as we endeavored to secure them by hand, and required 2.1-fold more time to be pinned and captured. When induced to bite a beaker after being grasped, the island snakes also delivered 2.1-fold greater quantities of venom when controlling for body size. The additional venom resulted from 2.1-fold larger pulses of venom ejected from the fangs. We found no effects of duration in captivity (2-36 months), which suggests an absence of long-term habituation of antipredator behaviors. Breeding bird surveys and Christmas bird counts indicated reduced population densities of avian predators on Catalina compared to the mainland. However, historical estimates confirmed that populations of foxes and introduced mammalian predators (cats and pigs) and antagonists (herbivorous ungulates) substantially exceeded those on the mainland in recent centuries, and therefore best explain the paradoxically exaggerated defensive behaviors exhibited by Catalina's rattlesnakes. These findings augment our understanding of anthropogenic effects on the behaviors of island animals and underscore how these effects can negatively affect human safety.

Is the Inverted Field Gradient in the Catalina Schist Terrane Primary or Constructional?

AbstractNew geothermometry using laser‐Raman data on carbonaceous material from low and intermediate grade rocks on Santa Catalina Island, California, together with existing thermobarometric data, show that there is a quasi‐continuous increase in peak metamorphic temperature from 327 ± 8°C in lawsonite blueschist facies rocks at the lowest structural levels, through ∼433°C in overlying epidote blueschists, 546 ± 20°C in albite‐epidote amphibolite facies rocks, to 650–730°C in amphibolite facies rocks at the top of the sequence. Rocks of different metamorphic grade are separated from one another by tectonic contacts across which temperature increases by ∼100°C in each case. Previously published geochronological data indicate that peak metamorphism in the highest grade rocks at 115 Ma preceded deposition of blueschist facies metasediments by ∼15 million years, so that the present inverted grade sequence does not represent an original inverted temperature gradient. The present structure results from progressive underplating of oceanic rocks in a cooling subduction zone following a high‐T metamorphic event at 115 Ma. An inverted temperature gradient of ≥100°C/km across the subduction channel likely existed during the high‐T event, decreased during underplating, and reached zero by ∼90 Ma.

Autochthonous carbon loading of macroalgae stimulates benthic biological nitrogen fixation rates in shallow coastal marine sediments.

Macroalgae, commonly known as seaweed, are foundational species in coastal ecosystems and contribute significantly to coastal primary production globally. However, the impact of macroalgal decomposition on benthic biological nitrogen fixation (BNF) after deposition to the seafloor remains largely unexplored. In this study, we measure BNF rates at three different sites at the Big Fisherman's Cove on Santa Catalina Island, CA, USA, which is representative of globally distributed rocky bottom macroalgal habitats. Unamended BNF rates varied among sites (0.001-0.05 nmol N g-1 h -1) and were generally within the lower end of previously reported ranges. We hypothesized that the differences in BNF between sites were linked to the availability of organic matter. Indeed, additions of glucose, a labile carbon source, resulted in 2-3 orders of magnitude stimulation of BNF rates in bottle incubations of sediment from all sites. To assess the impact of complex, autochthonous organic matter, we simulated macroalgal deposition and remineralization with additions of brown (i.e., Macrocystis pyrifera and Dictyopteris), green (i.e., Codium fragile), and red (i.e., Asparagopsis taxiformis) macroalgae. While brown and green macroalgal amendments resulted in 53- to 520-fold stimulation of BNF rates-comparable to the labile carbon addition-red alga was found to significantly inhibit BNF rates. Finally, we employed nifH sequencing to characterize the diazotrophic community associated with macroalgal decomposition. We observed a distinct community shift in potential diazotrophs from primarily Gammaproteobacteria in the early stages of remineralization to a community dominated by Deltaproteobacteria (e.g., sulfate reducers), Bacteroidia, and Spirochaeta toward the latter phase of decomposition of brown, green, and red macroalgae. Notably, the nifH-containing community associated with red macroalgal detritus was distinct from that of brown and green macroalgae. Our study suggests coastal benthic diazotrophs are limited by organic carbon and demonstrates a significant and phylum-specific effect of macroalgal loading on benthic microbial communities.

FIRST REPORT ON THE DISTRIBUTION AND EXTENSION OF SEAGRASS MEADOWS IN QUITASUEÑO CORAL BANK, SOUTHWESTERN CARIBBEAN

Seagrass beds constitute one of the world’s most productive marine ecosystems and are a source of food and shelter for a wide variety of species. The largest extension of seagrass meadows in the Seaflower Biosphere Reserve (Seaflower BR) is found around the Caribbean islands of San Andres, Old Providence, and Santa Catalina, with small patches around the cays Bolivar, Albuquerque, and Serranilla. Previous studies have reported the presence of seagrass beds in the Quitasueño Bank; however, they remain undescribed, without previous information about their extent and distribution within the coral complex. In November 2021, during the Seaflower Plus 2021 scientific expedition, extensive seagrass meadows were detected, and their distribution was determined through the interpretation of satellite images and analyses of information obtained in the field through rapid ecological assessments. It was determined that these meadows cover 619.7 ha, positioning Quitasueño as the second largest area in terms of seagrass coverage in the Seaflower BR after Old Providence and Santa Catalina islands. This new information increases the representativeness of the seagrass ecosystem within the National System of Protected Areas of Colombia and should be considered in future research and management efforts.

Dynamics of pH at Santa Catalina Island

The local expression of ocean acidification may depend on local oceanographic features in addition to global forcings. Our objective is to provide a baseline of pH behavior at Santa Catalina Island, situated within the unique oceanographic characteristics of the Southern California Bight, and to gain insight into ocean acidification at the island. Measurements of the upper water column (to 30-m depth) of pH, temperature, conductivity, chlorophyll and dissolved oxygen at Santa Catalina were made from a fixed mooring and by profiling the water column from a boat and on Self-Contained Underwater Breathing Apparatus (SCUBA). The average pH (8.095 at 18-m depth) was found to be higher than that reported off the nearby mainland and the Northern Channel Islands. The higher value is thought to result from both downwelling produced by internal waves as well as less upwelling at the island compared to other locations. Large modulations in pH at depth corresponded to advection of gradients by internal waves. Within the accuracy of the sensors there was no seasonal dependence detected at near-surface, nor a pH signal associated with the sub-surface chlorophyll and oxygen maxima. We conclude that marine life living at depths affected by internal waves experience significant variation in pH.

Notes on the marine algae of the International Biosphere Reserve Seaflower, Caribbean Colombia IX: new records of Lobophora declerckii, Taonia abbottiana and Verosphacela ebrachia for Colombia

Background and Aims: During the Seaflower Scientific Expedition in 2019, extensive seaweed collection was carried out around Old Providence and Santa Catalina islands. Despite the intensive phycological studies realized during the past decade, new reports of macroalgae are still recorded for the Seaflower Biosphere Reserve. The objective of this work is to present three new records of brown algae for Colombia.Methods: The algal sampling was carried out in September 2019 during the Seaflower Scientific Expedition. The samples were collected around the Providencia and Santa Catalina islands in coral patches ecosystems, by SCUBA diving at depths between 3 and 16 m. The algae collected were preserved in a 4% formalin/seawater solution. The identification was carried out using optical and stereoscopic microscopes. All specimens were deposited in the herbarium JIW of the Biology Department of the Universidad Nacional de Colombia, Bogotá, Colombia. Key results: Three species of brown algae are newly reported for Colombia: Lobophora declerckii, Taonia abbottiana and Verosphacela ebrachia. Verosphacela has been reported, to date, only from the type locality in Florida and from Isla Mujeres, in Mexico. Due to its cryptic and small habit, it may be much more common than actually reported. Lobophora declerckii is apparently the most common species of Lobophora in the Archipelago. Taonia abbottiana may be much more common than reported to date, but it is easily confused with Stypopodium zonale. Conclusions: Despite the intense phycological research carried out in the past decade in the Archipelago of San Andrés, Old Providence and Santa Catalina, there is still much to be discovered.

Genomic recovery lags behind demographic recovery in bottlenecked populations of the Channel Island fox, Urocyon littoralis.

With continued global change, recovery of species listed under the Endangered Species Act is increasingly challenging. One rare success was the recovery and delisting of the Channel Island fox (Urocyon littoralis) after 90%-99% population declines in the 1990s. While their demographic recovery was marked, less is known about their genetic recovery. To address genetic changes, we conducted the first multi-individual and population-level direct genetic comparison of samples collected before and after the recent bottlenecks. Using whole-exome sequencing, we found that already genetically depauperate populations were further degraded by the 1990s declines and remain low, particularly on San Miguel and Santa Rosa Islands, which underwent the most severe bottlenecks. The two other islands that experienced recent bottlenecks (Santa Cruz, and Santa Catalina islands) showed mixed results based on multiple metrics of genetic diversity. Previous island fox genomics studies showed low genetic diversity before the declines and no change after the demographic recovery, thus this is the first study to show a decrease in genetic diversity over time in U. littoralis. Additionally, we found that divergence between populations consistently increased over time, complicating prospects for using inter-island translocation as a conservation tool. The Santa Catalina subspecies is now federally listed as threatened, yet other de-listed subspecies are still recovering genetic variation which may limit their ability to adapt to changing environmental conditions. This study further demonstrates that species conservation is more complex than population size and that some island fox populations are not yet 'out of the woods'.

(2949) Proposal to conserve the name Quercus pacifica Nixon & C.H. Mull. against Q. pacifica Knowlt. (Fagaceae)

(2949) Quercus pacifica Nixon & C.H. Mull. in Novon 4: 391. 30 Nov 1994 [Angiosp.: Fag.], nom. cons. prop. Typus: U.S.A., California, Santa Barbara Co., rocky slope E. of Pelican Bay, Santa Cruz Island, alt. 100 ft., Clokey 4893 (BH-CHM). (H) Quercus pacifica Knowlt. in Rep. (Annual) U.S. Geol. Surv. 20(3): 43, t. 4, fig. 9, 10. 1900 [Foss.], nom. rej. prop. Typus: non designatus. In 1994, K.C. Nixon and C.H. Muller recognized the taxonomic distinctness of populations of shrubby oaks on three islands off the coast of southern California (Santa Cruz, Santa Catalina, and Santa Rosa Islands), and described them as a new species, Quercus pacifica Nixon & C.H. Mull. (in Novon 4: 391–392. 1994) with the holotype cited above. Subsequent genetic research has confirmed the distinctness of this taxon (Backs & Ashley in Amer. J. Bot. 103: 2115–2125. 2016). The taxon and the habitat are both endangered, so the taxon is subject to monitoring and conservation efforts across its limited range. Unfortunately, an earlier Quercus pacifica was published by F.H. Knowlton (in Rep. (Annual) U.S. Geol. Surv. 20(3): 43, t. 4, fig. 9, 10. 1900), based on Eocene fossils from Oregon, U.S.A. This was in a short paper, published as part of a geological report on a mining district in southern Oregon. Roland W. Brown (in J. Wash. Acad. Sci. 46: 104–108. 1956) subsequently excluded Q. pacifica Knowlt. from Fagaceae and made the new combination Caesalpinia pacifica (Knowlt.) R.W. Br. The placement in Fabaceae subfam. Caesalpinioideae, though not the assignment to Caesalpinia, was supported by Herendeen & Dilcher (in Amer. J. Bot. 78: 1–12. 1991). The priority of Knowlton's name over Q. pacifica Nixon & C.H. Mull. was first noted by Piers Trehane in the International Oak Society Checklist (http://www.oaknames.org/search/fullname.asp?id=506), where he said, “Nixon's name needs to be proposed for conservation”, but Trehane died before publishing a proposal. The name Quercus pacifica Nixon & C.H. Mull. has been used for this species in all recent references that deal with oaks of the region (e.g., Nixon & Muller in FNA Ed. Comm., Fl. N. Amer. N. Mex. 3: 471–506. 1997; Junak & al. in Barbour & al., Terrestr. Veg. California, ed. 3: 229–252. 2007; Tucker in Baldwin & al., Jepson Manual, ed. 2: 803–808. 2012; Jerome & al., Red List US Oaks. 2017). The species is considered endangered (Jerome & al., l.c.), so it is subject to monitoring and conservation efforts across its limited range, resulting in a plethora of studies, including studies of genetic structure and reproductive biology (Knapp in Standiforth & al., Proc. Fifth Symp. Oak Woodlands. 2002; Knapp, Oak Ecosyst. Restorat. Santa Catalina Island, California. 2011; in Monogr. W. N. Amer. Naturalist 7: 421–434. 2014; Pesendorfer & al. in Monogr. W. N. Amer. Naturalist 7: 246–259. 2014; in Curr. Zool. 63: 363–367. 2017; Backs & Ashley, l.c.) and conservation plans, all of which use the name Q. pacifica. Furthermore, the species is locally dominant in its very limited range, so its name forms part of the formal names of several communities in the widely used classification of California vegetation by Sawyer & al. (Manual California Veg., ed. 2. 2009), including the “Quercus dumosa – Quercus pacifica Alliance” and six formally named Associations. These vegetation type names are widely used in ecological and conservation studies of all groups of organisms, and all would have to be changed if the name of the co-dominant, Q. pacifica, were to change. Replacing Q. pacifica Nixon & C.H. Mull. with another name would therefore cause significant confusion among many active conservation programs as well as in the scientific literature. On the other hand, there is no reason to preserve the name Q. pacifica Knowlt., the basis of which is actually a legume. Conservation of Q. pacifica Nixon & C.H. Mull. will not affect the name Caesalpinia pacifica (Knowlt.) R.W. Br.; although Q. pacifica Knowlt. cannot be the correct name for a taxon when a later homonym has been conserved, it remains a legitimate name, and may serve as basionym for another combination (Art. 56 Note 1 of the ICN, Turland & al. in Regnum Veg. 159. 2018). ATW, https://orcid.org/0000-0002-7983-6374

Issue Information

Molecular EcologyVolume 32, Issue 4 p. i-ii ISSUE INFORMATIONFree Access Issue Information First published: 05 February 2023 https://doi.org/10.1111/mec.16510AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Graphical Abstract Cover Illustrations: Santa Catalina Island foxes exhibit minimal genetic diversity.Photo Credit: Jack Baldelli. Volume32, Issue4February 2023Pages i-ii RelatedInformation

“In Honorable Remembrance to All Generations”: Commemoration and the Making of Mormon Battalion Memory, 1921–2021

“In Honorable Remembrance to All Generations”: Commemoration and the Making of Mormon Battalion Memory, 1921–2021

Ear mite infection restructures otic microbial networks in conservation-reliant Santa Catalina Island foxes (Urocyon littoralis catalinae).

Ceruminous gland tumours are highly prevalent in the ear canals of Santa Catalina Island foxes (Urocyon littoralis catalinae). Previous work suggests that tumours may result from a combination of ectoparasites, disruption of the host-associated microbiome, and host immunopathology. More specifically, ear mite infection has been associated with broad-scale microbial dysbiosis marked by secondary bacterial infection with the opportunistic pathogen Staphylococcus pseudintermedius. Together, ear mites and S. pseudintermedius probably sustain chronic inflammation and promote conditions suitable for tumour development. In the present study, we expanded upon this framework by constructing otic microbial community networks for mite-infected and uninfected foxes sampled in 2017-2019. Across sampling years, we observed consistent signatures of microbial dysbiosis in mite-infected ear canals, including reduced microbial diversity and shifted abundance towards S. pseudintermedius. Network analysis further revealed that mite infection disrupts overall community structure. In mite-infected networks, interaction strengths between taxa were generally weaker, and numerous subnetworks disappeared altogether. We also found that two strains of S. pseudintermedius connected to the main network, suggesting that multistrain biofilm formation may be occurring. In contrast, S. pseudintermedius is peripheral in the uninfected network, with its only connections including a second strain of S. pseudintermedius and the possible competitor Acinetobacter rhizosphaerae. Finally, the lineup of potential keystone taxa shifted across disease states. Fusobacteria spp., a carcinogenesis-promoting microbe, assumed a keystone role in the mite-infected community. Considered together, these findings provide insights into how mite infection may destabilize the microbiome and ultimately contribute to tumour development in this island endemic species.

A decade of invertebrate recruitment at Santa Catalina Island, California.

Marine fouling communities have long provided model systems for studying the ecology of community development, and settlement plates are the tool of choice for this purpose. Decades of plate deployments provide a baseline against which present-day trends can be interpreted, with one classic trend being the ultimate dominance of plates by colonial and encrusting taxa. Here we report the results of annual deployments of settlement plates from 2010 to 2021 in the shallow sub-tidal of southern California, where the recruitment of invertebrates and algae was recorded photographically, and resolved to functional group (solitary, encrusting, and arborescent) and the lowest taxon possible. The communities on these plates differed among years, with trends in abundances varying by functional group and taxon; solitary taxa consistently were abundant, but encrusting taxa declined in abundance. Seawater temperature and the subsurface concentration of chlorophyll a differed among years, and there was a weak inverse association between temperature and the abundances of encrusting taxa. Long-term increases in seawater temperature therefore could serve as a mechanism causing fouling communities to change. Because of the prominence of encrusting taxa in fouling communities, the shifts in abundance of this functional group reported here may portend ecologically significant changes in fouling communities exposed to warmer seawater because of an alleviation of competition for a classically limiting resource (i.e., space).

Macroalgal physical structure predicts variation in some attributes of temperate fish assemblages better than macroalgal species composition

The importance of vegetative habitat in influencing distribution patterns, species interactions, and biodiversity is well documented in marine ecosystems, yet most previous studies on macroalgal–fish relationships have focused on influences of density and identity of macroalgae, often ignoring how the unique physical structure provided by each alga contributes to patterns. We tested whether the distribution, abundance, and biomass of rocky reef fishes could be predicted as well or better by measures of physical structure of macroalgae than by species identity and abundance. Divers visually sampled fishes and macroalgae at seven sites spread over several km at Santa Catalina Island, California, over a 1-year period, to examine how the distribution patterns of fishes related to spatiotemporal differences in the macroalgal assemblage. We found that variation in the composition, density, and diversity of the fish assemblage was equally or better explained by macroalgal structure (total surface area and height) than by macroalgal species density. In contrast, biomass and vertical distribution of fishes were better predicted by macroalgal species identity and density than by macroalgal physical structure. Of the macroalgal attributes, surface area was the best predictor of fish abundance and multivariate assemblage structure (species and their densities). However, much of the spatiotemporal variation in the fish assemblage was not explained by macroalgae, indicating that even in habitats visually dominated by macroalgae, macrophytes are only one of many factors that drive spatiotemporal variation in community structure. Our results suggest that quantifying the physical structure provided by marine macroalgae can be more useful than macroalgal species identity in predicting some aspects of fish assemblage structure.

Movements and diving behavior of Risso’s dolphins in the Southern California Bight

Risso’s dolphins (Grampus griseus), uncommon prior to the 1970’s, are now regularly observed within the Southern California Bight. During long-term cetacean monitoring programs on United States Navy range areas in the Southern California Bight from 2009–2019, we deployed 16 Argos-linked satellite tags on Risso’s to acquire objective, detailed depictions of their movements and behaviors. Individuals were tracked for a median of 10.7 days (range = 0.8 – 19.7). Kernel density estimation suggested individuals utilized the entire Southern California Bight with the 50% core use area centered around San Clemente and Santa Catalina Islands where most of the tag deployments occurred. Grand median dive depth was 101 m (max = 528) and dive duration was 5.6 min (max = 11.1). We used generalized mixed models to assess seasonal and environmental effects on distribution and diving behavior including month, distance to shore, time of day, lunar phase, sea surface temperature, and chlorophyll-aresiduals. Animals were further from shore (including islands) during a full versus new moon and from the mainland during the last versus first quarter moon. Animals also tended to be closer to land in the fall and early winter months. Dives were deeper yet shorter during the night, during a full moon, and when animals were further offshore. Animals conducted nearly twice as many dives at night compared to day, though deep dives (> 500 m) occurred at all times of day. This study provides insights into Risso’s distribution and behavioral trends while identifying priorities for future research.

Lack of avian predators is associated with behavioural plasticity in nest construction and height in an island songbird

Orange-crowned warblers, Leiothlypis celata sordida , breeding on the California Channel Islands exhibit remarkable variation in their nest structure and placement, providing an intriguing exception to the general pattern that avian nest structure and nest site selection are highly conserved characters. We examined nest construction at both the population and individual scale to test whether warblers on Santa Catalina Island change their nest construction in response to nest height. At the population level, warblers built both lighter, grass-dominated ground nests and heavier off-ground nests that contained more rigid materials and less grass. The probability of nest success was significantly and positively correlated with nest height. At the individual level, we found the same individuals were capable of building on- and off-ground nests between nesting attempts within the same season. However, nest construction was highly variable among individuals and not significantly correlated with nest success after controlling for nest height. We suggest this observed behavioural plasticity in nest construction and nest height is a hierarchical response to the absence of avian predators. Reduced risk from avian predators appears to allow the warblers to use a variety of nest sites, thereby necessitating increased flexibility in nest construction. • Santa Catalina Island orange-crowned warblers varied in nest construction behaviour. • Off-ground nests were heavier and contained more twigs than ground nests. • Individual females built nests of different materials at different heights. • Nest height, rather than nest construction, was associated with nest success. • Plasticity in nesting behaviour may allow warblers to use a range of nest sites.

Genomic Assessment of Cancer Susceptibility in the Threatened Catalina Island Fox (Urocyon littoralis catalinae).

Small effective population sizes raise the probability of extinction by increasing the frequency of potentially deleterious alleles and reducing fitness. However, the extent to which cancers play a role in the fitness reduction of genetically depauperate wildlife populations is unknown. Santa Catalina island foxes (Urocyon littoralis catalinae) sampled in 2007–2008 have a high prevalence of ceruminous gland tumors, which was not detected in the population prior to a recent bottleneck caused by a canine distemper epidemic. The disease appears to be associated with inflammation from chronic ear mite (Otodectes) infections and secondary elevated levels of Staphyloccus pseudointermedius bacterial infections. However, no other environmental factors to date have been found to be associated with elevated cancer risk in this population. Here, we used whole genome sequencing of the case and control individuals from two islands to identify candidate loci associated with cancer based on genetic divergence, nucleotide diversity, allele frequency spectrum, and runs of homozygosity. We identified several candidate loci based on genomic signatures and putative gene functions, suggesting that cancer susceptibility in this population may be polygenic. Due to the efforts of a recovery program and weak fitness effects of late-onset disease, the population size has increased, which may allow selection to be more effective in removing these presumably slightly deleterious alleles. Long-term monitoring of the disease alleles, as well as overall genetic diversity, will provide crucial information for the long-term persistence of this threatened population.