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1. Diet of a threatened endemic fox reveals variation in sandy beach resource use on California Channel Islands

   https://doi.org/10.1371/journal.pone.0258919  

   Page, Henry M.; Schamel, Juliann; Emery, Kyle A.; Schooler, Nicholas K.; Dugan, Jenifer E.; Guglielmino, Angela; Schroeder, Donna M.; Palmstrom, Linnea; Hubbard, David M.; Miller, Robert J. (October 2021, PLOS ONE)

   Hyrenbach, David (Ed.)

   The coastal zone provides foraging opportunities for insular populations of terrestrial mammals, allowing for expanded habitat use, increased dietary breadth, and locally higher population densities. We examined the use of sandy beach resources by the threatened island fox ( Urocyon littoralis ) on the California Channel Islands using scat analysis, surveys of potential prey, beach habitat attributes, and stable isotope analysis. Consumption of beach invertebrates, primarily intertidal talitrid amphipods ( Megalorchestia spp.) by island fox varied with abundance of these prey across sites. Distance-based linear modeling revealed that abundance of giant kelp ( Macrocystis pyrifera ) wrack, rather than beach physical attributes, explained the largest amount of variation in talitrid amphipod abundance and biomass across beaches. δ 13 C and δ 15 N values of fox whisker (vibrissae) segments suggested individualism in diet, with generally low δ 13 C and δ 15 N values of some foxes consistent with specializing on primarily terrestrial foods, contrasting with the higher isotope values of other individuals that suggested a sustained use of sandy beach resources, the importance of which varied over time. Abundant allochthonous marine resources on beaches, including inputs of giant kelp, may expand habitat use and diet breadth of the island fox, increasing population resilience during declines in terrestrial resources associated with climate variability and long-term climate change. 

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2. Dietary niche partitioning between Coastal Giant Salamanders (Dicamptodon tenebrosus) and Coastal Cutthroat Trout (Oncorhynchus clarkii clarkii)

   https://doi.org/10.1007/s10750-025-05934-x  

   Arismendi, Ivan; Ain, Najma; Gerth, William; Bury, Gwendolynn; Zatkos, Lauren (July 2025, Hydrobiologia)

   Understanding the mechanisms that enable species coexistence is essential for explaining community structure and biodiversity. We tested the hypothesis that dietary niche partitioning facilitates coexistence between two dominant stream predators in western North America: Coastal Giant Salamanders (Dicamptodon tenebrosus) and Coastal Cutthroat Trout (Oncorhynchus clarkii clarkii). These aquatic predators are important regulators of community dynamics and ecosystem processes in stream networks. We analyzed stomach contents from 81 salamanders and 96 trout collected via electrofishing in a 6-km section of Lookout Creek, Oregon, during low flow conditions in summer. We predicted that salamanders, primarily nocturnal benthic feeders, and trout, visual consumers of both terrestrial and aquatic prey, would exhibit distinct diets reducing direct diet overlap. We identified 4,897 prey items, classifying them into aquatic (50) and terrestrial (77) sources across 127 categories. Salamanders primarily preyed on aquatic invertebrates (Trichoptera, Ephemeroptera, and Plecoptera), while trout consumed a mix of terrestrial and aquatic invertebrates (Diptera, Trichoptera, and Plecoptera). Partial dietary overlap confirmed niche differentiation as a likely mechanism facilitating the coexistence of trout and salamanders. These findings highlight the role of dietary partitioning in structuring predator communities and inform predictions of how environmental changes may impact stream ecosystems. 

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3. Population expansion, divergence, and persistence in Western Fence Lizards (Sceloporus occidentalis) at the northern extreme of their distributional range

   https://doi.org/10.1038/s41598-022-10233-9  

   Davis, Hayden R.; Des Roches, Simone; Anderson, Roger A.; Leaché, Adam D. (April 2022, Scientific Reports)

   Abstract Population dynamics within species at the edge of their distributional range, including the formation of genetic structure during range expansion, are difficult to study when they have had limited time to evolve. Western Fence Lizards (Sceloporus occidentalis) have a patchy distribution at the northern edge of their range around the Puget Sound, Washington, where they almost exclusively occur on imperiled coastal habitats. The entire region was covered by Pleistocene glaciation as recently as 16,000 years ago, suggesting that populations must have colonized these habitats relatively recently. We tested for population differentiation across this landscape using genome-wide SNPs and morphological data. A time-calibrated species tree supports the hypothesis of a post-glacial establishment and subsequent population expansion into the region. Despite a strong signal for fine-scale population genetic structure across the Puget Sound with as many as 8–10 distinct subpopulations supported by the SNP data, there is minimal evidence for morphological differentiation at this same spatiotemporal scale. Historical demographic analyses suggest that populations expanded and diverged across the region as the Cordilleran Ice Sheet receded. Population isolation, lack of dispersal corridors, and strict habitat requirements are the key drivers of population divergence in this system. These same factors may prove detrimental to the future persistence of populations as they cope with increasing shoreline development associated with urbanization. 

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4. Trophic Ecology of Threatened Sympatric Coastal Dolphins and Other Odontocetes in North‐Western Madagascar

   https://doi.org/10.1111/mms.70027  

   Caputo, Michelle; Kiszka, Jeremy_J; Andrianarivelo, Norbert; Jonas, Ariana; Andrianantenaina, Boris; Paz, Valeria; Cerchio, Salvatore (May 2025, Marine Mammal Science)

   ABSTRACT Investigating the foraging ecology and trophic interactions of threatened marine predators is critical to assess how community changes due to anthropogenic activities will affect predator–prey relationships. Two species of threatened coastal dolphins, the Indian Ocean humpback dolphin (Sousa plumbea) and the Indo‐Pacific bottlenose dolphin (Tursiops aduncus), occur off Nosy Be, north‐western Madagascar, in a region where artisanal fisheries are ecologically and socioeconomically important. Here, we investigated the feeding ecology of these two coastal dolphins and their trophic interactions with four other odontocetes using bulk stable carbon and nitrogen isotope analysis (δ¹³C andδ¹⁵N). Humpback dolphins had significantly enrichedδ¹³C values, reflecting a preference for coastal/benthic prey. Bottlenose dolphins had a broader isotopic niche, suggesting a broader range of prey and foraging habitats. The overlap in isotopic niche of all six odontocete species was limited, indicating partitioning of resources and habitats. Bayesian mass‐balance isotopic mixing models revealed that humpback dolphins forage primarily on reef planktivores (38.9%) and inner reef mesopredators (20.5%), while bottlenose dolphins had a broader diet, including reef‐associated (15%–32%) and pelagic prey (12%–23%). Our study reveals that the reliance on inshore prey by humpback dolphins may place them in competition with coastal fisheries. 

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5. Exploitation of a marine subsidy by a terrestrial invader

   https://doi.org/10.1007/s10530-024-03500-5  

   Winters, Christopher; Jurgela, Grace; Holway, David (December 2024, Biological Invasions)

   Abstract Intertidal environments receive energy from marine ecosystems in the form of marine wrack, which makes up the base of a food web that includes both intertidal and terrestrial consumers. Consumption of wrack by terrestrial consumers can elevate their abundance and alter how they interact with organisms in adjacent terrestrial environments. Although rarely documented, terrestrial invaders may exploit marine wrack subsides and potentially disrupt intertidal and terrestrial food webs. Here, we examine consumption of marine wrack resources by the introduced Argentine ant (Linepithema humile), which occurs commonly on beaches in southern California. In controlled trials the Argentine ant readily scavenged arthropod detritivores (amphipods and flies) abundant in wrack. In spite of obvious risks (e.g., exposure to tides, desiccation, thermal stress) associated with intertidal foraging, Argentine ant activity on beaches was comparable to that in spatially-paired, scrub environments. Foraging on beaches allowed ants to access higher densities of arthropod prey and carrion compared to those found in scrub environments. Stable isotope analyses provide evidence for extensive assimilation of marine-derived resources. Values of δ¹⁵N and δ¹³C for the Argentine ant were higher at beach sites than at scrub sites, and Argentine ant δ¹⁵N values broadly overlapped those of intertidal consumers at beach sites. Although ants are known to forage in intertidal environments, this study provides a novel example of an introduced ant species exploiting a cross-boundary subsidy. 

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