34 results on '"Cheryl S. Brehme"'
Search Results
2. Long‐term occupancy monitoring reveals value of moderate disturbance for an open‐habitat specialist, the Stephens' kangaroo rat (Dipodomys stephensi)
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Cheryl S. Brehme, Philip R. Gould, Denise R. Clark, and Robert N. Fisher
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colonization ,density ,extinction ,heteromyid ,invasive grass ,non‐native grass ,Ecology ,QH540-549.5 ,General. Including nature conservation, geographical distribution ,QH1-199.5 - Abstract
Abstract For species of conservation concern, long‐term monitoring is vital to properly characterize changes in population distribution and abundance over time. In addition, long‐term monitoring guides management decisions by informing and evaluating the efficacy of management actions. A long‐term monitoring initiative for the federally threatened Stephens' Kangaroo rat (Dipodomys stephensi, SKR) was established in 2005, across 628 hectares within Marine Corps Base Camp Pendleton (MCBCP), San Diego, California, USA. From 2005 to 2018, we tracked trends in area occupied by SKR, trends in relative SKR densities within occupied habitat, and modeled probabilities of SKR occupancy, colonization, extinction, with habitat, climate, and disturbance covariates. Area occupied by SKR increased almost 2‐fold from 2005 to 2018 on MCBCP, while density in occupied habitat increased almost 3‐fold. Increased area occupied was correlated with increases in estimated density among years, indicating SKR population growth occurs by expansion into suitable habitat patches, as well as increases in numbers within occupied habitat. SKR occupancy was positively associated with gentle slopes (40%). They were more likely to colonize previously unoccupied habitat when there were moderate levels of open ground (40–80%) and low shrub cover (10%), less open ground (40%). Additionally, probabilities of SKR occupancy and colonization were higher in areas with moderate levels of disturbance, which was positively associated with open ground and forb cover. We conclude that long‐term occupancy and density monitoring is effective in informing status and trends of spatially dynamic species and that moderate habitat‐based disturbance is compatible with the management of SKR.
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- 2024
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- View/download PDF
3. Interactions among rainfall, fire, forbs and non-native grasses predict occupancy dynamics for the endangered Pacific pocket mouse (Perognathus longimembris pacificus) in a Mediterranean-type ecosystem
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Cheryl S. Brehme, Sarah K. Thomsen, Devin Adsit-Morris, and Robert N. Fisher
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Heteromyid ,Invasive grass ,Occupancy ,Coastal sage scrub ,Habitat management ,Exotic grass ,Ecology ,QH540-549.5 - Abstract
It is important to understand species-habitat relationships to implement effective adaptive management for rare species. However, it can be challenging to assess habitat associations and their relationships to abiotic stressors in dynamic habitats without the insights that can be gained from long-term monitoring. We report results from the first six years of extensive track tube monitoring of the largest two of three remaining extant populations of federally endangered Pacific pocket mouse (Perognathus longimembris pacificus) in a coastal Mediterranean-type ecosystem on Marine Corps Base, Camp Pendleton in southern California, USA. We used dynamic occupancy and structural equation modeling to assess potential drivers of population trends that included habitat, fire history, rainfall, disturbance, and the presence of other small mammals. We found that the variables that best predicted mouse occupancy were moderate to high forb and perennial herb cover (40–80%), and moderate to high open ground (20–70%) and low non-native grass cover (20%) was also a strong predictor of lower PPM colonization and increased extinction probabilities, with the extent of non-native grass cover being strongly influenced by annual rainfall and recency of fire. Our study adds to the growing literature on effects of invasive annual grasses on native species in Mediterranean-type ecosystems. We suggest that habitat management could be based upon promotion of open forb and perennial herb dominated habitats with reduction of non-native grasses by prescribed fire and other methods. These types of spatial and temporal monitoring programs can support land managers by creating a monitoring and management feedback loop. They can reveal landscape and environmental variables associated with species persistence, inform habitat management goals, and help managers to assess the success of management actions on populations of conservation concern.
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- 2023
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- View/download PDF
4. Corrigendum: Impacts of a non-indigenous ecosystem engineer, the American beaver (Castor canadensis), in a biodiversity hotspot
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Jonathan Q. Richmond, Camm C. Swift, Thomas A. Wake, Cheryl S. Brehme, Kristine L. Preston, Barbara E. Kus, Edward L. Ervin, Scott Tremor, Tritia Matsuda, and Robert N. Fisher
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invasive species ,hydrology ,ecosystem ,ecoregion ,Southern California ,invasional meltdown ,General. Including nature conservation, geographical distribution ,QH1-199.5 - Published
- 2023
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- View/download PDF
5. Fecal metabarcoding of the endangered Pacific pocket mouse (Perognathus longimembris pacificus) reveals a diverse and forb rich diet that reflects local habitat availability
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Amy G. Vandergast, Cheryl S. Brehme, Deborah Iwanowicz, Robert S. Cornman, Devin Adsit‐Morris, and Robert N. Fisher
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amplicon sequencing ,diet preference ,fecal sampling ,habitat restoration ,Heteromyidae ,ITS2 gene ,Ecology ,QH540-549.5 - Abstract
Abstract Information on diet breadth and preference can assist in understanding links between food resources and population growth and inform habitat restoration for rare herbivores. We assessed the diet of the endangered Pacific pocket mouse using metabarcoding of fecal samples and compared it to plant community composition in long‐term study plots in two populations on Marine Corps Base Camp Pendleton, San Diego County, CA. Fecal samples (n = 221) were collected between spring 2016 and fall 2017 during monthly live‐trap surveys. Concurrently, percent cover and plant phenology were measured in plots centered on trap locations. Fecal samples were sequenced with paired‐end reads of the internal transcribed spacer 2 region of the nuclear ribosomal gene, and the resulting amplicons were matched to a regionally specific database. Seventy‐three plant taxa were detected, which were mostly forbs and perennial herbs (70–90%). Diet composition differed between populations, years, seasons, and plots. Overall, diet and local habitat composition in plots were significantly correlated. However, we detected some differences in above‐ground seed availability and proportion in fecal samples that indicate diet preferences for some forbs, perennial herbs, and native bunch grasses over perennial shrubs and non‐native grasses. This is the first study of PPM to pair plant phenology surveys with diet metabarcoding to estimate resource selection, and results suggest that managing habitat for diverse native forb communities and reducing non‐native grass cover may be beneficial for this critically endangered species.
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- 2023
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6. Elevated road segment (ERS) passage design may provide enhanced connectivity for amphibians, reptiles, and small mammals
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Cheryl S. Brehme, Stephanie Barnes, Brittany Ewing, Philip Gould, Cassie Vaughan, Michael Hobbs, Charles Tornaci, Sarah Holm, Hanna Sheldon, Jon Fiutak, and Robert N. Fisher
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road ecology ,road crossing ,passage ,herpetofauna ,design ,tunnel ,Evolution ,QH359-425 ,Ecology ,QH540-549.5 - Abstract
IntroductionDesigns for safe and effective road crossing structures for small animals are typically under-road microtunnels and culverts which have varying levels of effectiveness reported in the scientific literature. Many species, particularly migratory amphibians, may have limited ability to find and use passages if they are too far apart, resulting in substantial barrier effects.MethodsWe designed a novel open elevated passage (elevated road segment: ERS), similar to a low terrestrial bridge, that could theoretically be built to any length based upon species needs and movement characteristics. A 30 m length prototype ERS was installed along a forest road with a history of amphibian road mortality in Sierra National Forest, Fresno County, CA, USA. From 2018 to 2021, we monitored small animal activity under the ERS in relation to surrounding roadside and forest habitats using active infrared cameras.ResultsWe documented a total of 8,815 unique use events, using species specific independence criteria, across 22 species of amphibians (3), reptiles (4), and small mammals (15). Poisson regression modeling of taxonomic group activity under the ERS, roadside and forest, showed that amphibian activity was highest in the forest habitat, no differences were observed for reptiles, and small mammal activity was highest under the ERS. However, mean activity estimates under the ERS were equal to or greater than the open roadside habitat for all 22 species, suggesting that adding cover objects, such as downed logs and vegetation may further enhance passage use.DiscussionOverall, results showed that the design of the ERS crossing has potential to provide high connectivity for a wide range of amphibian, reptile, and small mammal species while reducing road mortality. ERS systems can also be used in areas with challenging terrain and other hydrological and environmental constraints. Incorporating current road ecology science, we provide supplemental ERS concept designs for secondary roads, primary roads and highways to help increase the options available for road mitigation planning for small animals.
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- 2023
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7. Range‐wide persistence of the endangered arroyo toad (Anaxyrus californicus) for 20+ years following a prolonged drought
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Cynthia J. Hitchcock, Elizabeth A. Gallegos, Adam R. Backlin, Russell Barabe, Peter H. Bloom, Kimberly Boss, Cheryl S. Brehme, Christopher W. Brown, Denise R. Clark, Elizabeth R. Clark, Kevin Cooper, Julie Donnell, Edward Ervin, Peter Famolaro, Kim M. Guilliam, Jacquelyn J. Hancock, Nicholas Hess, Steven Howard, Valerie Hubbartt, Patrick Lieske, Robert Lovich, Tritia Matsuda, Katherin Meyer‐Wilkins, Kamarul Muri, Barry Nerhus, Jeff Nordland, Brock Ortega, Robert Packard, Ruben Ramirez, Sam C. Stewart, Samuel Sweet, Manna Warburton, Jeffrey Wells, Ryan Winkleman, Kirsten Winter, Brian Zitt, and Robert N. Fisher
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amphibian decline ,California ,climate change ,endangered species ,riparian habitat ,Ecology ,QH540-549.5 - Abstract
Abstract Prolonged drought due to climate change has negatively impacted amphibians in southern California, U.S.A. Due to the severity and length of the current drought, agencies and researchers had growing concern for the persistence of the arroyo toad (Anaxyrus californicus), an endangered endemic amphibian in this region. Range‐wide surveys for this species had not been conducted for at least 20 years. In 2017–2020, we conducted collaborative surveys for arroyo toads at historical locations. We surveyed 88 of the 115 total sites having historical records and confirmed that the arroyo toad is currently extant in at least 61 of 88 sites and 20 of 25 historically occupied watersheds. We did not detect toads at almost a third of the surveyed sites but did detect toads at 18 of 19 specific sites delineated in the 1999 Recovery Plan to meet one of four downlisting criteria. Arroyo toads are estimated to live 7–8 years, making populations susceptible to prolonged drought. Drought is estimated to increase in frequency and duration with climate change. Mitigation strategies for drought impacts, invasive aquatic species, altered flow regimes, and other anthropogenic effects could be the most beneficial strategies for toad conservation and may also provide simultaneous benefits to several other native species that share the same habitat.
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- 2022
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8. Responses of migratory amphibians to barrier fencing inform the spacing of road underpasses: a case study with California tiger salamanders (Ambystoma californiense) in Stanford, CA, USA
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Cheryl S. Brehme, Jeff A. Tracey, Brittany A.I. Ewing, Michael T. Hobbs, Alan E. Launer, Tritia A. Matsuda, Esther M. Cole Adelsheim, and Robert N. Fisher
- Subjects
Road ecology ,Movement ecology ,Connectivity ,Amphibians ,Road mortality ,Passages ,Ecology ,QH540-549.5 - Abstract
Migratory amphibians are at high risk of negative impacts when roads intersect their upland and breeding habitats. Road mortality can reduce population abundance, survivorship, breeding, recruitment, and probability of long-term persistence. Increasingly, environmental planners recommend installation of under-road tunnels with barrier fencing to reduce mortality and direct amphibians towards the passages. Often, the permeability of these barrier and passage systems to amphibian population movements are unknown. We studied the movements of California tiger salamanders (CTS: Ambystoma californiense) in relation to solid and mesh barrier fencing attached to a 3-tunnel system between upland and breeding habitats in Stanford, California. We deployed active-trigger cameras along the fencing, used pattern recognition software to identify individuals by their unique spot patterns, and calculated individual salamander movement distances, speed, direction changes, and “success” at reaching the tunnel system. We found that migrating adult CTS moved an average of 40 m along barrier fencing before turning back into the habitat or “giving-up”. This short distance, in comparison to long migratory movements, may be explained by the orientation mechanisms salamanders use to reach their breeding sites. The probability CTS found a passage decreased rapidly with increasing distance from the tunnel system, particularly if individuals turned the “wrong” way after encountering the fence. Salamanders changed directions more often and spent more time along mesh fencing. Our results suggest that a maximum of 12.5 m between passages along CTS migration routes should allow approximately 90% of adult salamanders to encounter road crossings. Additionally, use of solid fencing or a visual barrier on mesh fencing may help to lead salamanders to passages most efficiently. These considerations can assist those seeking to design effective road mitigation for CTS and other migratory amphibians.
- Published
- 2021
- Full Text
- View/download PDF
9. Impacts of a Non-indigenous Ecosystem Engineer, the American Beaver (Castor canadensis), in a Biodiversity Hotspot
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Jonathan Q. Richmond, Camm C. Swift, Thomas A. Wake, Cheryl S. Brehme, Kristine L. Preston, Barbara E. Kus, Edward L. Ervin, Scott Tremor, Tritia Matsuda, and Robert N. Fisher
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invasive species ,hydrology ,ecosystem ,ecoregion ,Southern California ,invasional meltdown ,General. Including nature conservation, geographical distribution ,QH1-199.5 - Abstract
Non-native species having high per capita impacts in invaded communities are those that modulate resource availability and alter disturbance regimes in ways that are biologically incompatible with the native biota. In areas where it has been introduced by humans, American beaver (Castor canadensis) is an iconic example of such species due to its capacity to alter trophic dynamics of entire ecosystems and create new invasional pathways for other non-native species. The species is problematic in several watersheds within the Southern California-Northern Baja California Coast Ecoregion, a recognized hotspot of biodiversity, due to its ability to modify habitat in ways that favor invasive predators and competitors over the region's native species and habitat. Beaver was deliberately introduced across California in the mid-1900s and generally accepted as non-native to the region up to the early 2000s; however, articles promoting the idea that beaver may be a natural resident have gained traction in recent years, due in large part to the species' charismatic nature rather than by presentation of sound evidence. Here, we discuss the problems associated with beaver disturbance and its effects on conserving the region's native fauna and flora. We refute arguments underlying the claim that beaver is native to the region, and review paleontological, zooarchaeological, and historical survey data from renowned field biologists and naturalists over the past ~160 years to show that no evidence exists that beaver arrived by any means other than deliberate human introduction. Managing this ecosystem engineer has potential to reduce the richness and abundance of other non-native species because the novel, engineered habitat now supporting these species would diminish in beaver-occupied watersheds. At the same time, hydrologic functionality would shift toward more natural, ephemeral conditions that favor the regions' native species while suppressing the dominance of the most insidious invaders.
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- 2021
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- View/download PDF
10. Quantifying climate sensitivity and climate-driven change in North American amphibian communities
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David A. W. Miller, Evan H. Campbell Grant, Erin Muths, Staci M. Amburgey, Michael J. Adams, Maxwell B. Joseph, J. Hardin Waddle, Pieter T. J. Johnson, Maureen E. Ryan, Benedikt R. Schmidt, Daniel L. Calhoun, Courtney L. Davis, Robert N. Fisher, David M. Green, Blake R. Hossack, Tracy A. G. Rittenhouse, Susan C. Walls, Larissa L. Bailey, Sam S. Cruickshank, Gary M. Fellers, Thomas A. Gorman, Carola A. Haas, Ward Hughson, David S. Pilliod, Steven J. Price, Andrew M. Ray, Walt Sadinski, Daniel Saenz, William J. Barichivich, Adrianne Brand, Cheryl S. Brehme, Rosi Dagit, Katy S. Delaney, Brad M. Glorioso, Lee B. Kats, Patrick M. Kleeman, Christopher A. Pearl, Carlton J. Rochester, Seth P. D. Riley, Mark Roth, and Brent H. Sigafus
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Science - Abstract
Amphibians have seen large population declines, but the key drivers are hard to establish. Here, Miller et al. investigate trends of occupancy for 81 species of amphibians across North America and find greater sensitivity to water availability during breeding and winter conditions than mean climate.
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- 2018
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11. Effects of urbanization and habitat composition on site occupancy of two snake species using regional monitoring data from southern California
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Milan J. Mitrovich, Jay E. Diffendorfer, Cheryl S. Brehme, and Robert N. Fisher
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Ecology ,QH540-549.5 - Abstract
Detection data from a regional, reptile-monitoring program conducted by the U.S. Geological Survey were analyzed to understand the effects of urbanization and habitat composition on site occupancy of the coachwhip (Masticophis flagellum) and striped racer (M. lateralis) in coastal southern California. Likelihood-based occupancy models indicated striped racers responded to habitat composition, favoring scrub-dominated sites. Coachwhips also responded to habitat composition, favoring open habitats. However, unlike racers, coachwhip spatial population dynamics were strongly associated with the fragmentation and isolation of natural areas caused by urbanization. The odds of coachwhips occupying a site were 64 times greater in large connected areas than the most urbanized and fragmented sites. For coachwhips within urbanized and fragmented sites, the odds of extinction were 10 times greater and odds of colonization were five times lower than in large connected sites. Observed differences between the species in habitat use and specificity are supported by telemetry studies and corroborate existing knowledge of historical patterns of occurrence within the region. Movement data on the coachwhip and striped racer indicate the coachwhip is a wider-ranging species with a greater propensity to encounter roads and other edge environments. Collectively, the results suggest there is widespread loss of the coachwhip from the region, and that long-term persistence of remaining populations is dependent on metapopulation dynamics. The substantially different response of the two species to land-use change serves as a caution against the casual use of closely related species as surrogates in the development of species-specific conservation plans. Keywords: Connectivity, Extinction, Habitat fragmentation, Isolation, Masticophis flagellum, Masticophis fuliginosus, Masticophis lateralis, Occupancy
- Published
- 2018
- Full Text
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12. Responses of migratory amphibians to barrier fencing inform the spacing of road underpasses: a case study with California tiger salamanders (Ambystoma californiense) in Stanford, CA, USA
- Author
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Robert N. Fisher, Jeff A. Tracey, Michael T. Hobbs, Tritia Matsuda, Esther M. Cole Adelsheim, Alan E. Launer, Brittany A.I. Ewing, and Cheryl S. Brehme
- Subjects
Amphibian ,education.field_of_study ,Connectivity ,biology ,Ecology ,Road ecology ,Passages ,Population ,Ambystoma californiense ,biology.organism_classification ,Fencing ,Short distance ,Road mortality ,Fishery ,Movement ecology ,Amphibians ,Geography ,Habitat ,biology.animal ,Salamander ,education ,Tiger salamander ,Ecology, Evolution, Behavior and Systematics ,QH540-549.5 ,Nature and Landscape Conservation - Abstract
Migratory amphibians are at high risk of negative impacts when roads intersect their upland and breeding habitats. Road mortality can reduce population abundance, survivorship, breeding, recruitment, and probability of long-term persistence. Increasingly, environmental planners recommend installation of under-road tunnels with barrier fencing to reduce mortality and direct amphibians towards the passages. Often, the permeability of these barrier and passage systems to amphibian population movements are unknown. We studied the movements of California tiger salamanders (CTS: Ambystoma californiense) in relation to solid and mesh barrier fencing attached to a 3-tunnel system between upland and breeding habitats in Stanford, California. We deployed active-trigger cameras along the fencing, used pattern recognition software to identify individuals by their unique spot patterns, and calculated individual salamander movement distances, speed, direction changes, and “success” at reaching the tunnel system. We found that migrating adult CTS moved an average of 40 m along barrier fencing before turning back into the habitat or “giving-up”. This short distance, in comparison to long migratory movements, may be explained by the orientation mechanisms salamanders use to reach their breeding sites. The probability CTS found a passage decreased rapidly with increasing distance from the tunnel system, particularly if individuals turned the “wrong” way after encountering the fence. Salamanders changed directions more often and spent more time along mesh fencing. Our results suggest that a maximum of 12.5 m between passages along CTS migration routes should allow approximately 90% of adult salamanders to encounter road crossings. Additionally, use of solid fencing or a visual barrier on mesh fencing may help to lead salamanders to passages most efficiently. These considerations can assist those seeking to design effective road mitigation for CTS and other migratory amphibians.
- Published
- 2021
13. Impacts of a Non-indigenous Ecosystem Engineer, the American Beaver (Castor canadensis), in a Biodiversity Hotspot
- Author
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Edward L. Ervin, Barbara E. Kus, Thomas A. Wake, Cheryl S. Brehme, Scott Tremor, Camm C. Swift, Robert N. Fisher, Tritia Matsuda, Kristine L. Preston, and Jonathan Q. Richmond
- Subjects
Castor canadensis ,ecosystem ,Beaver ,biology ,Ecology ,Biodiversity ,General. Including nature conservation, geographical distribution ,Introduced species ,hydrology ,QH1-199.5 ,biology.organism_classification ,Indigenous ,Ecosystem engineer ,Biodiversity hotspot ,Southern California ,invasive species ,Geography ,biology.animal ,Species richness ,invasional meltdown ,ecoregion - Abstract
Non-native species having high per capita impacts in invaded communities are those that modulate resource availability and alter disturbance regimes in ways that are biologically incompatible with the native biota. In areas where it has been introduced by humans, American beaver (Castor canadensis) is an iconic example of such species due to its capacity to alter trophic dynamics of entire ecosystems and create new invasional pathways for other non-native species. The species is problematic in several watersheds within the Southern California-Northern Baja California Coast Ecoregion, a recognized hotspot of biodiversity, due to its ability to modify habitat in ways that favor invasive predators and competitors over the region's native species and habitat. Beaver was deliberately introduced across California in the mid-1900s and generally accepted as non-native to the region up to the early 2000s; however, articles promoting the idea that beaver may be a natural resident have gained traction in recent years, due in large part to the species' charismatic nature rather than by presentation of sound evidence. Here, we discuss the problems associated with beaver disturbance and its effects on conserving the region's native fauna and flora. We refute arguments underlying the claim that beaver is native to the region, and review paleontological, zooarchaeological, and historical survey data from renowned field biologists and naturalists over the past ~160 years to show that no evidence exists that beaver arrived by any means other than deliberate human introduction. Managing this ecosystem engineer has potential to reduce the richness and abundance of other non-native species because the novel, engineered habitat now supporting these species would diminish in beaver-occupied watersheds. At the same time, hydrologic functionality would shift toward more natural, ephemeral conditions that favor the regions' native species while suppressing the dominance of the most insidious invaders.
- Published
- 2021
14. Quantitative SWOT analysis: A structured and collaborative approach to reintroduction site selection for the endangered Pacific pocket mouse
- Author
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Rachel Y. Chock, William B. Miller, Shauna N.D. King, Cheryl S. Brehme, Robert N. Fisher, Hans Sin, Peggy Wilcox, Jill Terp, Scott Tremor, Matthew R. Major, Korie Merrill, Wayne D. Spencer, Sherri Sullivan, and Debra M. Shier
- Subjects
Ecology ,Nature and Landscape Conservation - Published
- 2022
15. Range-wide persistence of the endangered arroyo toad (
- Author
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Cynthia J, Hitchcock, Elizabeth A, Gallegos, Adam R, Backlin, Russell, Barabe, Peter H, Bloom, Kimberly, Boss, Cheryl S, Brehme, Christopher W, Brown, Denise R, Clark, Elizabeth R, Clark, Kevin, Cooper, Julie, Donnell, Edward, Ervin, Peter, Famolaro, Kim M, Guilliam, Jacquelyn J, Hancock, Nicholas, Hess, Steven, Howard, Valerie, Hubbartt, Patrick, Lieske, Robert, Lovich, Tritia, Matsuda, Katherin, Meyer-Wilkins, Kamarul, Muri, Barry, Nerhus, Jeff, Nordland, Brock, Ortega, Robert, Packard, Ruben, Ramirez, Sam C, Stewart, Samuel, Sweet, Manna, Warburton, Jeffrey, Wells, Ryan, Winkleman, Kirsten, Winter, Brian, Zitt, and Robert N, Fisher
- Abstract
Prolonged drought due to climate change has negatively impacted amphibians in southern California, U.S.A. Due to the severity and length of the current drought, agencies and researchers had growing concern for the persistence of the arroyo toad (
- Published
- 2021
16. Predictability of Invasive Argentine Ant Distribution Across Mediterranean Ecoregions of Southern California
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Robert N. Fisher, Cheryl S. Brehme, Emily Perkins, Tritia Matsuda, and Jonathan Q. Richmond
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Mediterranean climate ,Ecology ,biology ,Range (biology) ,Biodiversity ,Vegetation ,biology.organism_classification ,Ecoregion ,Geography ,Habitat ,Argentine ant ,Linepithema ,Ecology, Evolution, Behavior and Systematics - Abstract
The invasiveness of nonnative taxa can vary across a landscape due to environmental gradients, suggesting that location-dependent management strategies may be more effective at reducing spread compared to a “one size fits all” approach across the entire introduced range. Using bait stations placed along linear transects within habitat preserves, we tested for effects of ecoregion, vegetation, soil moisture, habitat edge type (i.e., moisture source), and distance from edges on the presence of the invasive Argentine ant Linepithema humile in San Diego County, California, a region with high indigenous biodiversity and numerous rare and protected species. Our results showed an inverse relationship between the presence of native ant species and the presence of the Argentine ant across ecoregions, with the latter reaching peak abundance in the coastal terrace. Argentine ant presence was negatively associated with distance from all edge types regardless of location, but the magnitude of this effect varied among ecoregions. In the xeric foothill and inland valleys, the probability of occurrence was nearly 0 at distances of 200 m and 750 m from moisture edges, respectively, whereas in the coastal terrace, the probability remained above 0.80 at distances up to 1.25 km. When compared to previous studies at different spatial scales, these findings provide an alternative perspective on the invasiveness of the Argentine ant at the landscape level. Our results further suggest that efforts to control spread in regions with a Mediterranean climate may be more successful in inland areas, where the ant is likely to have lower environmental tolerance and native ant species may be better able to generate biotic resistance. In contrast, different tactics and expectations may be necessary for coastal areas, where the same constraints are diminished or absent.
- Published
- 2021
17. The influence of species life history and distribution characteristics on species responses to habitat fragmentation in an urban landscape
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Seth P. D. Riley, Staci M. Amburgey, Carlton J. Rochester, David A. W. Miller, Cheryl S. Brehme, Stacie A. Hathaway, Robert N. Fisher, and Katy S. Delaney
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0106 biological sciences ,Amphibian ,Mammals ,Habitat fragmentation ,Ecology ,010604 marine biology & hydrobiology ,Biogeography ,Species distribution ,Biodiversity ,Vertebrate ,Introduced species ,Biology ,010603 evolutionary biology ,01 natural sciences ,biology.animal ,Animals ,Animal Science and Zoology ,Species richness ,Ecology, Evolution, Behavior and Systematics ,Ecosystem - Abstract
Fragmentation within urbanized environments often leads to a loss of native species diversity; however, variation exists in responses among-species and among-populations within species. We aimed to identify patterns in species biogeography in an urbanized landscape to understand anthropogenic effects on vertebrate communities and identify species that are more sensitive or resilient to landscape change. We investigated patterns in species richness and species responses to fragmentation in southern Californian small vertebrate communities using multispecies occupancy models and determined factors associated with overall commonness and sensitivity to patch size for 45 small vertebrate species both among and within remaining non-developed patches. In general, smaller patches had fewer species, with amphibian species richness being particularly sensitive to patch size effects. Mammals were generally more common, occurring both in a greater proportion of patches and a higher proportion of the sites within occupied patches. Alternatively, amphibians were generally restricted to larger patches but were more ubiquitous within smaller patches when occupied. Species range size was positively correlated with how common a species was across and within patches, even when controlling for only patches that fell within a species' range. We found sensitivity to patch size was greater for more fecund species and depended on where the patch occurred within a species' range. While all taxa were more likely to occur in patches in the warmer portions of their ranges, amphibians and mammals were more sensitive to fragmentation in these warmer areas as compared to the rest of their ranges. Similarly, amphibians occurred at a smaller proportion of sites within patches in drier portions of their ranges. Mammals occurred at a higher proportion of sites that were also in drier portions of their range while reptiles did not differ in their sensitivity to patch size by range position. We demonstrate that taxonomy, life history, range size and range position can predict commonness and sensitivity of species across this highly fragmented yet biodiverse landscape. The impacts of fragmentation on species communities within an urban landscape depend on scale, with differences emerging among and within species and populations.
- Published
- 2020
18. Longevity and population age structure of the arroyo southwestern toad (Anaxyrus californicus) with drought implications
- Author
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Tim E. Hovey, Stacie A. Hathaway, Cheryl S. Brehme, Robert N. Fisher, Manna L. Warburton, and Drew C. Stokes
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0106 biological sciences ,Mediterranean climate ,Amphibian ,education.field_of_study ,Ecology ,biology ,010604 marine biology & hydrobiology ,Ephemeral key ,Population ,Endangered species ,Surface-water hydrology ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,Geography ,Southwestern toad ,biology.animal ,Skeletochronology ,education ,Ecology, Evolution, Behavior and Systematics ,Nature and Landscape Conservation - Abstract
The arroyo southwestern toad is a specialized and federally endangered amphibian endemic to the coastal plains and mountains of central and southern California and northwestern Baja California. It is largely unknown how long these toads live in natural systems, how their population demographics vary across occupied drainages, and how hydrology affects age structure. We used skeletochronology to estimate the ages of adult arroyo toads in seven occupied drainages with varying surface water hydrology in southern California. We processed 179 adult toads with age estimates between 1 and 6 years. Comparisons between skeletochronological ages and known ages of PIT tagged toads showed that skeletochronology likely underestimated toad age by up to 2 years, indicating they may live to 7 or 8 years, but nonetheless major patterns were evident. Arroyo toads showed sexual size dimorphism with adult females reaching a maximum size of 12 mm greater than males. Population age structure varied among the sites. Age structure at sites with seasonally predictable surface water was biased toward younger individuals, which indicated stable recruitment for these populations. Age structures at the ephemeral sites were biased toward older individuals with cohorts roughly corresponding to higher rainfall years. These populations are driven by surface water availability, a stochastic process, and thus more unstable. Based on our estimates of toad ages, climate predictions of extreme and prolonged drought events could mean that the number of consecutive dry years could surpass the maximum life span of toads making them vulnerable to extirpation, especially in ephemeral freshwater systems. Understanding the relationship between population demographics and hydrology is essential for predicting species resilience to projected changes in weather and rainfall patterns. The arroyo toad serves as a model for understanding potential responses to climatic and hydrologic changes in Mediterranean stream systems. We recommend development of adaptive management strategies to address these threats.
- Published
- 2018
19. An objective road risk assessment method for multiple species: ranking 166 reptiles and amphibians in California
- Author
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Cheryl S. Brehme, Stacie A. Hathaway, and Robert N. Fisher
- Subjects
0106 biological sciences ,Sustainable development ,Ecology ,business.industry ,010604 marine biology & hydrobiology ,Ecology (disciplines) ,Geography, Planning and Development ,Environmental resource management ,Road ecology ,Wildlife ,010603 evolutionary biology ,01 natural sciences ,Geography ,Ranking ,Taxonomic rank ,Landscape ecology ,business ,Risk assessment ,Nature and Landscape Conservation - Abstract
Transportation and wildlife agencies may consider the need for barrier structures and safe wildlife road-crossings to maintain the long-term viability of wildlife populations. In order to prioritize these efforts, it is important to identify species that are most at risk of extirpation from road-related impacts. Our goal was to identify reptiles and amphibians in California most susceptible to road mortality and fragmentation. With over 160 species and a lack of species-specific research data, we developed an objective risk assessment method based upon road ecology science. Risk scoring was based upon a suite of life history and space-use characteristics associated with negative road effects applied in a hierarchical manner from individuals to species. We evaluated risk to both aquatic and terrestrial connectivity and calculated buffer distances to encompass 95% of population-level movements. We ranked species into five relative categories of road-related risk (very-high to very-low) based upon 20% increments of all species scores. All chelonids, 72% of snakes, 50% of anurans, 18% of lizards and 17% of salamander species in California were ranked at high or very-high risk from negative road impacts. Results were largely consistent with local and global scientific literature in identifying high risk species and groups. This comparative risk assessment method provides a science-based framework to identify species most susceptible to negative road impacts. The results can inform regional-scale road mitigation planning and prioritization efforts and threat assessments for special-status species. We believe this approach is applicable to numerous landscapes and taxonomic groups.
- Published
- 2018
20. Track tube construction and field protocol for small mammal surveys with emphasis on the endangered Pacific pocket mouse (Perognathus longimembris pacificus)
- Author
-
Melanie Anne T. Burlaza, Robert N. Fisher, Jeremy B. Sebes, Tritia Matsuda, Cheryl S. Brehme, Denise R. Clark, and Devin T. Adsit-Morris
- Subjects
Geography ,biology ,Perognathus longimembris ,Endangered species ,Zoology ,Small mammal ,biology.organism_classification - Published
- 2019
21. Quantifying climate sensitivity and climate-driven change in North American amphibian communities
- Author
-
Brent H. Sigafus, Seth P. D. Riley, Andrew M. Ray, Gary M. Fellers, Robert N. Fisher, Carlton J. Rochester, Carola A. Haas, Cheryl S. Brehme, Tracy A. G. Rittenhouse, Brad M. Glorioso, Maureen E. Ryan, Adrianne B. Brand, Maxwell B. Joseph, William J. Barichivich, Katy S. Delaney, Mark F. Roth, Lee B. Kats, Christopher A. Pearl, Benedikt R. Schmidt, Pieter T. J. Johnson, Courtney L. Davis, Thomas A. Gorman, Daniel L. Calhoun, David S. Pilliod, J. Hardin Waddle, Ward Hughson, Michael J. Adams, Steven J. Price, Evan H. Campbell Grant, Sam S. Cruickshank, Blake R. Hossack, Rosi Dagit, Susan C. Walls, Walt Sadinski, Erin Muths, David M. Green, Patrick M. Kleeman, Staci M. Amburgey, Larissa L. Bailey, Daniel Saenz, David A. W. Miller, and Fish and Wildlife Conservation
- Subjects
0106 biological sciences ,Amphibian ,animal structures ,010504 meteorology & atmospheric sciences ,Occupancy ,Science ,Climate ,Climate Change ,Population Dynamics ,General Physics and Astronomy ,Climate change ,010603 evolutionary biology ,01 natural sciences ,General Biochemistry, Genetics and Molecular Biology ,Amphibians ,Species Specificity ,biology.animal ,Animals ,Ecosystem ,lcsh:Science ,skin and connective tissue diseases ,0105 earth and related environmental sciences ,Multidisciplinary ,Geography ,Community ,biology ,Ecology ,Temperature ,General Chemistry ,Models, Theoretical ,North America ,Climate sensitivity ,lcsh:Q ,Seasons ,sense organs ,Conservation biology ,Species richness ,Animal Distribution ,Algorithms - Abstract
Changing climate will impact species' ranges only when environmental variability directly impacts the demography of local populations. However, measurement of demographic responses to climate change has largely been limited to single species and locations. Here we show that amphibian communities are responsive to climatic variability, using >500,000 time-series observations for 81 species across 86 North American study areas. The effect of climate on local colonization and persistence probabilities varies among eco-regions and depends on local climate, species life-histories, and taxonomic classification. We found that local species richness is most sensitive to changes in water availability during breeding and changes in winter conditions. Based on the relationships we measure, recent changes in climate cannot explain why local species richness of North American amphibians has rapidly declined. However, changing climate does explain why some populations are declining faster than others. Our results provide important insights into how amphibians respond to climate and a general framework for measuring climate impacts on species richness. John Wesley Powell Center for Analysis and Synthesis - US Geological Survey U.S. Geological Survey-Amphibian Research and Monitoring Initiative (ARMI) U.S. Fish and Wildlife Service National Park Service U.S. Forest Service National Science Foundation [DEB-0841758, DEB-1149308] National Institutes of Health [R01GM109499] National Geographic Society Morris Animal Foundation David and Lucille Packard Foundation This work was conducted as part of the Amphibian Decline Working Group supported by the John Wesley Powell Center for Analysis and Synthesis, funded by the US Geological Survey. Funding and logistical support for field data collection came from a range of sources including the U.S. Geological Survey-Amphibian Research and Monitoring Initiative (ARMI), U.S. Fish and Wildlife Service, National Park Service, U.S. Forest Service, National Science Foundation (DEB-0841758, DEB-1149308), National Institutes of Health (R01GM109499), National Geographic Society, Morris Animal Foundation, and David and Lucille Packard Foundation. Data are deposited at the U.S. Geological Survey's John Wesley Powell Center for Analysis and Synthesis. This manuscript is contribution 654 of USGS ARMI. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
- Published
- 2018
22. Longevity and population age structure of the arroyo southwestern toad (
- Author
-
Robert N, Fisher, Cheryl S, Brehme, Stacie A, Hathaway, Tim E, Hovey, Manna L, Warburton, and Drew C, Stokes
- Subjects
skeletochronology ,amphibian ,amphibian decline ,endangered species ,southern California ,life span ,Original Research - Abstract
The arroyo southwestern toad is a specialized and federally endangered amphibian endemic to the coastal plains and mountains of central and southern California and northwestern Baja California. It is largely unknown how long these toads live in natural systems, how their population demographics vary across occupied drainages, and how hydrology affects age structure. We used skeletochronology to estimate the ages of adult arroyo toads in seven occupied drainages with varying surface water hydrology in southern California. We processed 179 adult toads with age estimates between 1 and 6 years. Comparisons between skeletochronological ages and known ages of PIT tagged toads showed that skeletochronology likely underestimated toad age by up to 2 years, indicating they may live to 7 or 8 years, but nonetheless major patterns were evident. Arroyo toads showed sexual size dimorphism with adult females reaching a maximum size of 12 mm greater than males. Population age structure varied among the sites. Age structure at sites with seasonally predictable surface water was biased toward younger individuals, which indicated stable recruitment for these populations. Age structures at the ephemeral sites were biased toward older individuals with cohorts roughly corresponding to higher rainfall years. These populations are driven by surface water availability, a stochastic process, and thus more unstable. Based on our estimates of toad ages, climate predictions of extreme and prolonged drought events could mean that the number of consecutive dry years could surpass the maximum life span of toads making them vulnerable to extirpation, especially in ephemeral freshwater systems. Understanding the relationship between population demographics and hydrology is essential for predicting species resilience to projected changes in weather and rainfall patterns. The arroyo toad serves as a model for understanding potential responses to climatic and hydrologic changes in Mediterranean stream systems. We recommend development of adaptive management strategies to address these threats.
- Published
- 2017
23. Permeability of Roads to Movement of Scrubland Lizards and Small Mammals
- Author
-
Jeff A. Tracey, Leroy R. McClenaghan, Cheryl S. Brehme, and Robert N. Fisher
- Subjects
Western fence lizard ,geography ,geography.geographical_feature_category ,Ecology ,biology ,High mortality ,Road ecology ,Forestry ,biology.organism_classification ,Dulzura kangaroo rat ,Shrubland ,Chaetodipus fallax ,medicine ,Deer mouse ,medicine.vector_of_disease ,Ecology, Evolution, Behavior and Systematics ,Nature and Landscape Conservation ,Cactus mouse - Abstract
A primary objective of road ecology is to understand and predict how roads affect connectivity of wildlife populations. Road avoidance behavior can fragment populations, whereas lack of road avoidance can result in high mortality due to wildlife-vehicle collisions. Many small animal species focus their activities to particular microhabitats within their larger habitat. We sought to assess how different types of roads affect the movement of small vertebrates and to explore whether responses to roads may be predictable on the basis of animal life history or microhabitat preferences preferences. We tracked the movements of fluorescently marked animals at 24 sites distributed among 3 road types: low-use dirt, low-use secondary paved, and rural 2-lane highway. Most data we collected were on the San Diego pocket mouse (Chaetodipus fallax), cactus mouse (Peromyscus eremicus), western fence lizard (Sceloporus occidentalis), orange-throated whiptail (Aspidoscelis hyperythra), Dulzura kangaroo rat (Dipodomys simulans) (dirt, secondary paved), and deer mouse (Peromyscus maniculatus) (highway only). San Diego pocket mice and cactus mice moved onto dirt roads but not onto a low-use paved road of similar width or onto the highway, indicating they avoid paved road substrate. Both lizard species moved onto the dirt and secondary paved roads but avoided the rural 2-lane rural highway, indicating they may avoid noise, vibration, or visual disturbance from a steady flow of traffic. Kangaroo rats did not avoid the dirt or secondary paved roads. Overall, dirt and secondary roads were more permeable to species that prefer to forage or bask in open areas of their habitat, rather than under the cover of rocks or shrubs. However, all study species avoided the rural 2-lane highway. Our results suggest that microhabitat use preferences and road substrate help predict species responses to low-use roads, but roads with heavy traffic may deter movement of a much wider range of small animal species. Resumen Un objetivo principal de la ecologia de caminos es entender y predecir como afectan los caminos la conectividad de las poblaciones silvestres. El comportamiento de evitacion de caminos puede fragmentar poblaciones, mientras que la falta de evitacion puede resultar en alta mortandad debido a colisiones. Muchas especies animales pequenas enfocan sus actividades a microhabitats particulares dentro de su habitat mayor. Buscamos estudiar como los diferentes tipos de caminos afectan el movimiento de pequenos vertebrados y conocer si ciertas respuestas hacia los caminos pueden ser predecibles basandose en la historia de vida del animal o el microhabitat. Rastreamos los movimientos de animales marcados con fluorescencia en 24 sitios distribuidos entre 3 tipos de caminos: tierra de bajo uso, camino secundario pavimentado de bajo uso, y carretera rural de 2 carriles. La mayoria de los datos que colectamos fueron sobre Chaetodipus fallax, Peromyscus eremicus, Sceloporus occidentalis, Aspidoscelis hyperythra, Dipodomys simulans (tierra, pavimentacion secundaria), y P. maniculatus (solamente en carretera). C. fallax y P. eremicus se movian hacia los caminos de tierra pero no hacia una carretera de baja pavimentacion de anchura similar o hacia la carretera, indicando que evitan los caminos con sustrato pavimentado. S. occidentalis y A. hyperythra se movian hacia la tierra y los caminos secundarios pavimentados pero evitaban la carretera rural de 2 carriles, indicando que pueden evitar el ruido, las vibraciones o el disturbio visual de un constante flujo de trafico. D. simulans no evitaba el camino de tierra ni los caminos secundarios con pavimento. En general, el camino de tierra y los caminos secundarios fueron mas permeables para las especies que prefieren forrajear o tomar el sol en areas abiertas de su habitat en lugar de bajo rocas o arbustos. D. simulans no evito el camino de tierra ni los caminos secundarios pavimentados. Sin embargo todas las especies estudiadas evitaron la carretera de 2 carriles. Nuestros resultados sugieren que las preferencias de uso de microhabitat y sustrato de caminos ayudan a predecir las respuestas de las especies hacia caminos de bajo uso, pero los caminos con trafico pesado pueden disuadir el movimiento de un rango mucho mayor de especies animales pequenas.
- Published
- 2013
24. Joint estimation of habitat dynamics and species interactions: disturbance reduces co-occurrence of non-native predators with an endangered toad
- Author
-
James D. Nichols, Robert N. Fisher, Cheryl S. Brehme, James E. Hines, and David A. W. Miller
- Subjects
geography ,geography.geographical_feature_category ,Occupancy ,Perennial stream ,Ecology ,Ephemeral key ,Endangered species ,Co-occurrence ,Biology ,Disturbance (ecology) ,Habitat ,Animal ecology ,Animal Science and Zoology ,Ecology, Evolution, Behavior and Systematics - Abstract
Summary 1. Ecologists have long been interested in the processes that determine patterns of species occurrence and co-occurrence. Potential short-comings of many existing empirical approaches that address these questions include a reliance on patterns of occurrence at a single time point, failure to account properly for imperfect detection and treating the environment as a static variable. 2. We fit detection and non-detection data collected from repeat visits using a dynamic site occupancy model that simultaneously accounts for the temporal dynamics of a focal prey species, its predators and its habitat. Our objective was to determine how disturbance and species interactions affect the co-occurrence probabilities of an endangered toad and recently introduced non-native predators in stream breeding habitats. For this, we determined statistical support for alternative processes that could affect co-occurrence frequency in the system. 3. We collected occurrence data at stream segments in two watersheds where streams were largely ephemeral and one watershed dominated by perennial streams. Co-occurrence probabilities of toads with non-native predators were related to disturbance frequency, with low co-occurrence in the ephemeral watershed and high co-occurrence in the perennial watershed. This occurred because once predators were established at a site, they were rarely lost from the site except in cases when the site dried out. Once dry sites became suitable again, toads colonized them much more rapidly than predators, creating a period of predator-free space. 4. We attribute the dynamics to a storage effect, where toads persisting outside the stream environment during periods of drought rapidly colonized sites when they become suitable again. Our results support that even in highly connected stream networks, temporal disturbance can structure frequencies with which breeding amphibians encounter non-native predators. 5. Dynamic multi-state occupancy models are a powerful tool for rigorously examining hypotheses about inter-species and species–habitat interactions. In contrast to previous methods that infer dynamic processes based on static patterns in occupancy, the approach we took allows the dynamic processes that determine species–species and species–habitat interactions to be directly estimated.
- Published
- 2012
25. Wildfires Alter Rodent Community Structure Across Four Vegetation Types in Southern California, USA
- Author
-
Carlton J. Rochester, Denise R. Clark, Cheryl S. Brehme, and Robert N. Fisher
- Subjects
Peromyscus californicus ,Peromyscus ,geography.geographical_feature_category ,biology ,Ecology ,fungi ,Coastal sage scrub ,Forestry ,Environmental Science (miscellaneous) ,biology.organism_classification ,Chaparral ,Dulzura kangaroo rat ,Chaetodipus fallax ,Geography ,Desert woodrat ,medicine ,Deer mouse ,medicine.vector_of_disease ,Ecology, Evolution, Behavior and Systematics - Abstract
We surveyed burned and unburned plots across four habitat reserves in San Diego County, California, USA, in 2005 and 2006, to assess the effects of the 2003 wildfires on the community structure and relative abundance of rodent species. The reserves each contained multiple vegetation types (coastal sage scrub, chaparral, woodland, and grassland) and spanned from 250 m to 1078 m in elevation. Multivariate analyses revealed a more simplified rodent community structure in all burned habitats in comparison to unburned habitats. Reduction in shrub and tree cover was highly predictive of changes in post-fire rodent community structure in the burned coastal sage scrub and chaparral habitats. Reduction in cover was not predictive for the less substantially burned woodlands and grasslands, for which we hypothesized that interspecific competition played a greater role in post-fire community structure. Across vegetation types, generalists and open habitat specialists typically increased in relative abundance, whereas closed habitat specialists decreased. We documented significant increases in relative abundance of the deer mouse (Peromyscus maniculatus Wagner) and Dulzura kangaroo rat (Dipodomys simulans Merriam). In contrast, we found significant decreases in relative abundance for the California mouse (Peromyscus californicus Gambel), San Diego pocket mouse (Chaetodipus fallax Merriam), desert woodrat (Neotoma lepida Thomas), and brush mouse (Peromyscus boylii Baird). Currently, our research program involves assessment of whether habitat conservation plans (HCPs) in southern California provide long-term protection to HCP covered species, as well as preserve ecosystem function. The scenario of increased wildfires needs to be incorporated into this assessment. We discuss our results in relation to management and conservation planning under a future scenario of larger and more frequent wildfires in southern California.
- Published
- 2011
26. Effects of Large-Scale Wildfires on Ground Foraging Ants (Hymenoptera: Formicidae) in Southern California
- Author
-
Carlton J. Rochester, Greta M. Turschak, Milan J. Mitrovich, Cheryl S. Brehme, Robert N. Fisher, and Tritia Matsuda
- Subjects
geography ,geography.geographical_feature_category ,Ecology ,biology ,Coastal sage scrub ,Foraging ,Community structure ,Species diversity ,Woodland ,Chaparral ,biology.organism_classification ,Grassland ,Insect Science ,Ecology, Evolution, Behavior and Systematics ,Riparian zone - Abstract
We investigated the effect of broad-scale wildfire on ground foraging ants within southern California. In October and November of 2003, two wildfires burned large portions of the wildlands within San Diego County. Between January 2005 and September 2006, we surveyed 63 plots across four sites to measure the effect of the fires on the ant assemblages present in four vegetation types: 1) coastal sage scrub, 2) chaparral, 3) grassland, and 4) woodland riparian. Thirty-six of the 63 plots were sampled before the fires between March 2001 and June 2003. Mixed model regression analyses, accounting for the burn history of each plot and our pre- and postfire sampling efforts, revealed that fire had a negative effect on ant species diversity. Multivariate analyses showed that ant community structure varied significantly among the four vegetation types, and only the ant assemblage associated with coastal sage scrub exhibited a significant difference between burned and unburned samples. The most notable change detected at the individual species level involved Messor andrei (Mayr), which increased from
- Published
- 2011
27. Reptile and Amphibian Responses to Large-Scale Wildfires in Southern California
- Author
-
Stacie A. Hathaway, Carlton J. Rochester, Denise R. Clark, Cheryl S. Brehme, Robert N. Fisher, and Drew C. Stokes
- Subjects
geography ,geography.geographical_feature_category ,biology ,Fire regime ,Ecology ,Phrynosoma coronatum ,Coastal sage scrub ,Species diversity ,biology.organism_classification ,Chaparral ,Shrubland ,Elgaria multicarinata ,Animal Science and Zoology ,Species richness ,Ecology, Evolution, Behavior and Systematics - Abstract
In 2003, southern California experienced several large fires that burned thousands of hectares of wildlife habitats and conserved lands. To investigate the effects of these fires on the reptile and amphibian communities, we compared the results from prefire herpetofauna and vegetation sampling to two years of postfire sampling across 38 burned and 17 unburned plots. The sampling plots were spread over four vegetation types and four open space areas within San Diego County. Our capture results indicated that burned chaparral and coastal sage scrub plots lost herpetofaunal species diversity after the fires and displayed a significant shift in overall community structure. Shrub and tree cover at the burned plots, averaged across the second and third postfire years, had decreased by 53% in chaparral and 75% in coastal sage scrub. Additionally, postfire herpetofauna community structure at burned plots was more similar to that found in unburned grasslands. In grassland and woodland/riparian vegetation plots, where shrub and tree cover was not significantly affected by fires, we found no differences in the herpetofaunal species diversity or community composition. At the individual species level, Sceloporus occidentalis was the most abundant reptile in these areas both before and after the fires. We saw increases in the net capture rates for several lizard species, including Aspidoscelis tigris, Phrynosoma coronatum, and Uta stansburiana in burned chaparral plots and Aspidoscelis hyperythra and U. stansburiana in burned coastal sage scrub plots. The toad, Bufo boreas, was detected at significantly fewer burned plots in chaparral after the fires. Additionally, we documented decreases in the number of plots occupied by lizards (Elgaria multicarinata), salamanders (Batrachoseps major), and snakes (Coluber constrictor, Lampropeltis getula, Pituophis catenifer, and Masticophis lateralis) in coastal sage scrub and chaparral after the fires. We discuss the individual species results as they relate to such life-history traits as the susceptibility to initial mortality, the response to the altered postfire habitat, and shifts in the availability of potential prey. We foresee that a continued unnatural fire regime will result in a simplification of the southern California reptile and amphibian communities.
- Published
- 2010
28. Responses in Bird Communities to Wildland Fires in Southern California
- Author
-
Robert N. Fisher, Carlton J. Rochester, Cheryl S. Brehme, Stacie A. Hathaway, Mark B. Mendelsohn, and Drew C. Stokes
- Subjects
geography ,geography.geographical_feature_category ,biology ,Ecology ,ved/biology ,Coastal sage scrub ,ved/biology.organism_classification_rank.species ,Species diversity ,Forestry ,Vegetation ,Environmental Science (miscellaneous) ,biology.organism_classification ,Chaparral ,Shrub ,Grassland ,Relative species abundance ,Ecology, Evolution, Behavior and Systematics ,Riparian zone - Abstract
There is a growing body of literature covering the responses of bird species to wildland fire events. Our study was unique among these because we investigated the effects of large-scale wildland fires on entire bird communities across multiple vegetation types. We conducted avian point counts during the breeding seasons for two years before and two years after the Cedar and Otay Fires in 2003 in southern California. Our balanced sampling effort took place at two sites, one low-elevation and one high-elevation, each containing replicate stations (burned and unburned) within five vegetation types: chaparral, coastal sage scrub, grassland, oak woodland, and riparian. Although fire caused some degree of change in the vegetation structure at all of our impacted survey points, we found that the post-fire shrub and tree cover was significantly lower in only two of the vegetation types within the low-elevation site, coastal sage scrub and chaparral. We found no significant changes in cover at the high-elevation site. Using univariate and multivariate analyses, we tested whether the fires were associated with a change in bird species diversity, community structure, and the relative abundance of individuals within a species. We found that species diversity changed in only one circumstance: it increased in coastal sage scrub at the low-elevation site. Multivariate analyses revealed significant differences in the post-fire bird community structure in the low-elevation chaparral, low-elevation coastal sage scrub, and the high-elevation grassland communities. Vegetation characteristics altered by fire, such as decreases in shrub and tree cover, influenced the changes we observed in the bird communities. The relative abundance of some species (lazuli bunting [Passerina amoena] and horned lark [Eremophila alpestris]) significantly increased after the fires, while other species declined significantly (Anna’s hummingbird [Calypte anna], wrentit [Chamaea fasciata], and bushtit [Psaltriparus minimus]). We detected mixed results for the spotted towhee (Pipilo maculatus), which increased in burned chaparral and declined in burned coastal sage scrub within the low-elevation site. We suggest that the observed responses of birds to these fires may be attributed to: (1) the availability of nearby unburned refugia, (2) the continued suitability of post-fire vegetation at the study sites, and (3) the generally high mobility of this taxon.
- Published
- 2008
29. An improved camera trap for amphibians, reptiles, small mammals, and large invertebrates
- Author
-
Michael T. Hobbs and Cheryl S. Brehme
- Subjects
0106 biological sciences ,Physiology ,Animal Types ,High variability ,lcsh:Medicine ,Equipment ,Wildlife ,010603 evolutionary biology ,01 natural sciences ,Body Temperature ,Amphibians ,Trap (computing) ,Medicine and Health Sciences ,Photography ,Animals ,lcsh:Science ,Small Animals ,Remote sensing ,Invertebrate ,Mammals ,High rate ,Multidisciplinary ,Ecology ,010604 marine biology & hydrobiology ,lcsh:R ,Organisms ,Biology and Life Sciences ,Eukaryota ,Reptiles ,Sampling (statistics) ,Cameras ,Invertebrates ,Optical Equipment ,Physiological Parameters ,Vertebrates ,Amniotes ,Engineering and Technology ,Camera trap ,Environmental science ,lcsh:Q ,Detection rate ,Zoology ,Research Article ,Active camera - Abstract
Camera traps are valuable sampling tools commonly used to inventory and monitor wildlife communities but are challenged to reliably sample small animals. We introduce a novel active camera trap system enabling the reliable and efficient use of wildlife cameras for sampling small animals, particularly reptiles, amphibians, small mammals and large invertebrates. It surpasses the detection ability of commonly used passive infrared (PIR) cameras for this application and eliminates problems such as high rates of false triggers and high variability in detection rates among cameras and study locations. Our system, which employs a HALT trigger, is capable of coupling to digital PIR cameras and is designed for detecting small animals traversing small tunnels, narrow trails, small clearings and along walls or drift fencing.
- Published
- 2017
30. Metabarcoding of Fecal Samples to Determine Herbivore Diets: A Case Study of the Endangered Pacific Pocket Mouse
- Author
-
Joshua R. Kohn, Cynthia R. Adams, Amy G. Vandergast, Robert N. Fisher, Robert S. Cornman, Cheryl S. Brehme, and Deborah D. Iwanowicz
- Subjects
0301 basic medicine ,Rodent ,Endangered species ,lcsh:Medicine ,Artificial Gene Amplification and Extension ,Plant Science ,Polymerase Chain Reaction ,California ,Feces ,Database and Informatics Methods ,Databases, Genetic ,Medicine and Health Sciences ,lcsh:Science ,Data Management ,Multidisciplinary ,Ecology ,biology ,Plant Anatomy ,Perognathus longimembris ,Plants ,Trophic Interactions ,Community Ecology ,Habitat ,Seeds ,Seasons ,Heteromyidae ,Sequence Analysis ,Research Article ,Computer and Information Sciences ,Sequence Databases ,Rodentia ,Extinction, Biological ,Research and Analysis Methods ,03 medical and health sciences ,Species Specificity ,biology.animal ,Animals ,DNA Barcoding, Taxonomic ,Computer Simulation ,Herbivory ,Molecular Biology Techniques ,Sequencing Techniques ,Molecular Biology ,Nutrition ,Taxonomy ,Herbivore ,lcsh:R ,Endangered Species ,Ecology and Environmental Sciences ,Organisms ,Biology and Life Sciences ,Sequence Analysis, DNA ,Ribosomal RNA ,biology.organism_classification ,Diet ,Biological Databases ,030104 developmental biology ,lcsh:Q ,Species richness ,Sequence Alignment - Abstract
Understanding the diet of an endangered species illuminates the animal's ecology, habitat requirements, and conservation needs. However, direct observation of diet can be difficult, particularly for small, nocturnal animals such as the Pacific pocket mouse (Heteromyidae: Perognathus longimembris pacificus). Very little is known of the dietary habits of this federally endangered rodent, hindering management and restoration efforts. We used a metabarcoding approach to identify source plants in fecal samples (N = 52) from the three remaining populations known. The internal transcribed spacers (ITS) of the nuclear ribosomal loci were sequenced following the Illumina MiSeq amplicon strategy and processed reads were mapped to reference databases. We evaluated a range of threshold mapping criteria and found the best-performing setting generally recovered two distinct mock communities in proportions similar to expectation. We tested our method on captive animals fed a known diet and recovered almost all plant sources, but found substantial heterogeneity among fecal pellets collected from the same individual at the same time. Observed richness did not increase with pooling of pellets from the same individual. In field-collected samples, we identified 4-14 plant genera in individual samples and 74 genera overall, but over 50 percent of reads mapped to just six species in five genera. We simulated the effects of sequencing error, variable read length, and chimera formation to infer taxon-specific rates of misassignment for the local flora, which were generally low with some exceptions. Richness at the species and genus levels did not reach a clear asymptote, suggesting that diet breadth remained underestimated in the current pool of samples. Large numbers of scat samples are therefore needed to make inferences about diet and resource selection in future studies of the Pacific pocket mouse. We conclude that our minimally invasive method is promising for determining herbivore diets given a library of sequences from local plants.
- Published
- 2016
31. Permeability of roads to movement of scrubland lizards and small mammals
- Author
-
Cheryl S, Brehme, Jeff A, Tracey, Leroy R, McClenaghan, and Robert N, Fisher
- Subjects
Conservation of Natural Resources ,Species Specificity ,Animals ,Lizards ,Rodentia ,Transportation ,California ,Ecosystem ,Fluorescence ,Locomotion - Abstract
A primary objective of road ecology is to understand and predict how roads affect connectivity of wildlife populations. Road avoidance behavior can fragment populations, whereas lack of road avoidance can result in high mortality due to wildlife-vehicle collisions. Many small animal species focus their activities to particular microhabitats within their larger habitat. We sought to assess how different types of roads affect the movement of small vertebrates and to explore whether responses to roads may be predictable on the basis of animal life history or microhabitat preferences preferences. We tracked the movements of fluorescently marked animals at 24 sites distributed among 3 road types: low-use dirt, low-use secondary paved, and rural 2-lane highway. Most data we collected were on the San Diego pocket mouse (Chaetodipus fallax), cactus mouse (Peromyscus eremicus), western fence lizard (Sceloporus occidentalis), orange-throated whiptail (Aspidoscelis hyperythra), Dulzura kangaroo rat (Dipodomys simulans) (dirt, secondary paved), and deer mouse (Peromyscus maniculatus) (highway only). San Diego pocket mice and cactus mice moved onto dirt roads but not onto a low-use paved road of similar width or onto the highway, indicating they avoid paved road substrate. Both lizard species moved onto the dirt and secondary paved roads but avoided the rural 2-lane rural highway, indicating they may avoid noise, vibration, or visual disturbance from a steady flow of traffic. Kangaroo rats did not avoid the dirt or secondary paved roads. Overall, dirt and secondary roads were more permeable to species that prefer to forage or bask in open areas of their habitat, rather than under the cover of rocks or shrubs. However, all study species avoided the rural 2-lane highway. Our results suggest that microhabitat use preferences and road substrate help predict species responses to low-use roads, but roads with heavy traffic may deter movement of a much wider range of small animal species.
- Published
- 2012
32. Joint estimation of habitat dynamics and species interactions: disturbance reduces co-occurrence of non-native predators with an endangered toad
- Author
-
David A W, Miller, Cheryl S, Brehme, James E, Hines, James D, Nichols, and Robert N, Fisher
- Subjects
Conservation of Natural Resources ,Rivers ,Predatory Behavior ,Endangered Species ,Population Dynamics ,Animals ,Desiccation ,Introduced Species ,Models, Biological ,Bufonidae ,California ,Ecosystem - Abstract
1. Ecologists have long been interested in the processes that determine patterns of species occurrence and co-occurrence. Potential short-comings of many existing empirical approaches that address these questions include a reliance on patterns of occurrence at a single time point, failure to account properly for imperfect detection and treating the environment as a static variable. 2. We fit detection and non-detection data collected from repeat visits using a dynamic site occupancy model that simultaneously accounts for the temporal dynamics of a focal prey species, its predators and its habitat. Our objective was to determine how disturbance and species interactions affect the co-occurrence probabilities of an endangered toad and recently introduced non-native predators in stream breeding habitats. For this, we determined statistical support for alternative processes that could affect co-occurrence frequency in the system. 3. We collected occurrence data at stream segments in two watersheds where streams were largely ephemeral and one watershed dominated by perennial streams. Co-occurrence probabilities of toads with non-native predators were related to disturbance frequency, with low co-occurrence in the ephemeral watershed and high co-occurrence in the perennial watershed. This occurred because once predators were established at a site, they were rarely lost from the site except in cases when the site dried out. Once dry sites became suitable again, toads colonized them much more rapidly than predators, creating a period of predator-free space. 4. We attribute the dynamics to a storage effect, where toads persisting outside the stream environment during periods of drought rapidly colonized sites when they become suitable again. Our results support that even in highly connected stream networks, temporal disturbance can structure frequencies with which breeding amphibians encounter non-native predators. 5. Dynamic multi-state occupancy models are a powerful tool for rigorously examining hypotheses about inter-species and species-habitat interactions. In contrast to previous methods that infer dynamic processes based on static patterns in occupancy, the approach we took allows the dynamic processes that determine species-species and species-habitat interactions to be directly estimated.
- Published
- 2012
33. Herpetological Monitoring Using a Pitfall Trapping Design in Southern California
- Author
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Carlton J. Rochester, Drew C. Stokes, Ted J. Case, Stacie A. Hathaway, Cheryl S. Brehme, and Robert N. Fisher
- Subjects
Oceanography ,Geography ,Trapping - Published
- 2008
34. Metabarcoding of Fecal Samples to Determine Herbivore Diets: A Case Study of the Endangered Pacific Pocket Mouse.
- Author
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Deborah D Iwanowicz, Amy G Vandergast, Robert S Cornman, Cynthia R Adams, Joshua R Kohn, Robert N Fisher, and Cheryl S Brehme
- Subjects
Medicine ,Science - Abstract
Understanding the diet of an endangered species illuminates the animal's ecology, habitat requirements, and conservation needs. However, direct observation of diet can be difficult, particularly for small, nocturnal animals such as the Pacific pocket mouse (Heteromyidae: Perognathus longimembris pacificus). Very little is known of the dietary habits of this federally endangered rodent, hindering management and restoration efforts. We used a metabarcoding approach to identify source plants in fecal samples (N = 52) from the three remaining populations known. The internal transcribed spacers (ITS) of the nuclear ribosomal loci were sequenced following the Illumina MiSeq amplicon strategy and processed reads were mapped to reference databases. We evaluated a range of threshold mapping criteria and found the best-performing setting generally recovered two distinct mock communities in proportions similar to expectation. We tested our method on captive animals fed a known diet and recovered almost all plant sources, but found substantial heterogeneity among fecal pellets collected from the same individual at the same time. Observed richness did not increase with pooling of pellets from the same individual. In field-collected samples, we identified 4-14 plant genera in individual samples and 74 genera overall, but over 50 percent of reads mapped to just six species in five genera. We simulated the effects of sequencing error, variable read length, and chimera formation to infer taxon-specific rates of misassignment for the local flora, which were generally low with some exceptions. Richness at the species and genus levels did not reach a clear asymptote, suggesting that diet breadth remained underestimated in the current pool of samples. Large numbers of scat samples are therefore needed to make inferences about diet and resource selection in future studies of the Pacific pocket mouse. We conclude that our minimally invasive method is promising for determining herbivore diets given a library of sequences from local plants.
- Published
- 2016
- Full Text
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