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USGS2024

Distribution, abundance, and breeding activities of the Least Bell's Vireo at Marine Corps Base Camp Pendleton, California—2020 annual report

Executive Summary The purpose of this report is to provide the Marine Corps with an annual summary of abundance, breeding activity, demography, and habitat use of endangered Least Bell’s Vireos ( Vireo bellii pusillus ) at Marine Corps Base Camp Pendleton (MCBCP, or Base). Surveys for the Least Bell's Vireo were conducted at MCBCP, California, between April 1 and July 10, 2020. Core survey areas and a subset of non-core areas in drainages containing riparian habitat suitable for vireos were surveyed 3–4 times. We detected 669 territorial male vireos and 16 transient vireos in core survey areas. An additional 156 territorial male vireos were detected in non-core survey areas. Territorial vireos were detected on all 10 drainages/sites surveyed (core and non-core areas). Of the vireo territories in core areas, 88 percent were on the 4 most populated drainages, with the Santa Margarita River containing 69 percent of all territories. In core areas, 79 percent of male vireos were confirmed as paired; 83 percent of male vireos in non-core areas were confirmed as paired. The number of documented Least Bell’s Vireo territories in core survey areas on MCBCP (669) increased 39 percent from 2019 to 2020. The number of territories in all core survey area drainages increased by one or more between 2019 and 2020. The substantial increase in vireo numbers on MCBCP (39 percent) was consistent with population changes in surrounding areas, including the lower San Luis Rey River (26 percent), Marine Corps Air Station, Camp Pendleton (58 percent), and the middle San Luis Rey River (7 percent). Most core-area vireo territories (69 percent of males) occurred in willow ( Salix spp.) riparian habitat. An additional 4 percent of birds occupied willow habitat co-dominated by Western sycamores ( Platanus racemosa ) or Fremont cottonwoods ( Populus fremontii ). Eighteen percent of territories were found in riparian scrub dominated by mule fat ( Baccharis salicifolia ) or sandbar willow ( S. exigua ). Upland scrub was used by 7 percent or fewer vireos; 1 percent of territories occurred in non-native vegetation, and less than 1 percent of vireo territories occurred in habitat co-dominated by coast live oak ( Quercus agrifolia ) and sycamore. In 2019, MCBCP began operating an artificial seep along the Santa Margarita River. The artificial seep pumped water to the surface from March through August each year during daylight hours and was designed to increase the amount of surface water present to enhance Southwestern Willow Flycatcher ( Empidonax traillii extimus ; flycatcher) breeding habitat. Although this enhancement was designed to benefit flycatchers, few flycatchers have inhabited the seep and proposed seep areas within the past several years. Therefore, vireos were selected as a surrogate species to determine effects of the habitat enhancement. This report presents preliminary analyses of vireo and vegetation response to the existing artificial seep. We sampled vegetation in the Seep site and three Reference sites to determine the effects of a new water diversion dam that was completed in 2019 and a surface water enhancement seep pump installed along the Santa Margarita River. We found minor differences in non-native vegetation cover between Reference sites and the Seep site. However, soil moisture was higher at the Reference sites compared to the Seep site. The effect of the seep pump may have been masked by high precipitation in the bio-year (July 1‒June 30) before 2020, limited time for the water diversion to have an effect, well-draining soil, and the non-operation of two to three of the six seep outlets. We color banded and resighted color banded Least Bell’s Vireos to evaluate adult site fidelity, between-year movement, and the effect of surface water enhancement on vireo site fidelity and between-year movement. We banded 146 Least Bell's Vireos for the first time during the 2020 season. Birds banded included 27 adult vireos and 119 juvenile vireos. All adult vireos were banded with unique color combinations. The juvenile vireos (all nestlings) were banded with a single gold numbered federal band on the left leg. We resighted and identified 85 Least Bell's Vireos banded before the 2020 breeding season on Base in 2020. Of the 85, 13 vireos were originally banded on the San Luis Rey River, 2 were banded in Baja California Sur, 1 was banded at Marine Corps Air Station, Camp Pendleton, and the remaining birds were banded at MCBCP. Adult birds of known age ranged from 1 to 8 years old. Most returning adult vireos showed strong between-year site fidelity. Of the adults present in 2019 and 2020, 74 percent, (79 percent of males; 40 percent of females) returned to within 100 m of their previous territory. The average between-year movement for returning adult vireos was 0.3 plus or minus (±) 0.8 kilometer (km). The average movement of first-year vireos detected in 2020 that fledged from a known nest on MCBCP in 2019 was 4.7±7.0 km. One first-year vireo that originated at MCBCP moved off Base and was detected at Murrieta Creek, 23.0 km from his natal territory. We monitored Least Bell's Vireo pairs to evaluate the effects of surface water enhancement on nest success and breeding productivity. Vireos were monitored at one Seep site and three Reference sites. Base personnel plan to install a second seep pump at one of the Reference sites in the future, at which time the status of the monitoring site will change from Reference to Seep. Nesting activity was monitored between March 31 and July 28 in 52 territories within the Seep and Reference sites (12 at the Seep site and 40 at Reference sites). All territories were occupied by pairs, and all but one territory was fully monitored, meaning all nesting attempts were monitored at these territories. One vireo territory within a Reference site was partially monitored. During the monitoring period, 94 nests (25 in the Seep site and 69 in Reference sites) were monitored. Breeding productivity was similar at the Seep site and Reference sites (3.7 and 2.9 young per pair, respectively), with 75 percent of Seep pairs and 79 percent of Reference pairs successfully fledging at least 1 young in 2020. Compared to Reference sites, the Seep site had a higher proportion of all eggs that hatched and also a higher proportion of nests with eggs that hatched. Conversely, a lower proportion of hatchlings and nests that had hatchlings fledged at the Seep site than at Reference sites. According to the best model, nest survival in 2020 was not affected by treatment (Seep versus Reference), although the second best model that included treatment was also well supported. Completed nests at the Seep site were likely to be as successful as nests at Reference sites in 2020 (57 percent and 59 percent, respectively). Predation was believed to be the primary source of nest failure at both sites. Predation accounted for 90 percent and 73 percent of nest failures at Seep and Reference sites, respectively. Failure of the remaining eight nests was attributed to the collapse of the nesting substrate, exposure to rain and flooding, and other unknown reasons. Fourteen plant species were used as hosts for vireo nests in 2020. In 2020, we found that at the Seep site, successful nests were placed in taller host plants and further from the edge of host plants (closer to the center) than unsuccessful nests. We found no difference in nest placement between the Seep site and the Reference sites.

California↗

USGS2024

Distribution, abundance, and breeding activities of the Least Bell's Vireo at Marine Corps Base Camp Pendleton, California—2021 annual report

Executive Summary The purpose of this report is to provide the Marine Corps with an annual summary of abundance, breeding activity, demography, and habitat use of endangered Least Bell’s Vireos ( Vireo bellii pusillus ) at Marine Corps Base Camp Pendleton (MCBCP or “Base”). Surveys for the Least Bell's Vireo were completed at MCBCP, California, between April 5 and July 13, 2021. Core survey areas and a subset of non-core areas in drainages containing riparian habitat suitable for vireos were surveyed three to four times. We detected 551 territorial male vireos and 26 transient vireos in core survey areas. An additional 98 territorial male vireos were detected in non-core survey areas. Transient vireos were detected on 8 of the 10 drainages/sites surveyed (core and non-core areas). Of the vireo territories in core areas, 89 percent were on the four most populated drainages, with the Santa Margarita River containing 70 percent of all territories in areas surveyed on Base. In core areas, 75 percent of male vireos were confirmed as paired; 76 percent of male vireos in non-core areas were confirmed as paired. The number of documented Least Bell’s Vireo territories in core survey areas on MCBCP decreased 18 percent from 2020 to 2021. The number of territories in all but two core survey area drainages decreased by one or more between 2020 and 2021. The decrease in vireo numbers on MCBCP (18 percent) was consistent with population changes in surrounding areas, including the lower San Luis Rey River (24-percent decrease) and the middle San Luis Rey River (6-percent decrease). Most core-area vireo territories (59 percent of males) were in willow ( Salix spp.) riparian habitat. An additional 7 percent of birds occupied willow habitat co-dominated by Western sycamores ( Platanus racemosa ) or Fremont cottonwoods ( Populus fremontii ). Of all the territories surveyed, 25 percent were in riparian scrub dominated by mule fat ( Baccharis salicifolia ) or sandbar willow ( S. exigua ). Upland scrub was used by 8 percent of vireos; 1 percent of vireo territories were in non-native vegetation, and less than 1 percent of vireo territories were in alder or drier habitats co-dominated by coast live oak ( Quercus agrifolia ) and sycamore. In 2019, MCBCP began operating an artificial seep along the Santa Margarita River; then, in 2021, two additional artificial seeps became operational. The artificial seeps pumped water to the surface starting in March and ending in August each year during daylight hours and were designed to increase the amount of surface water present to enhance Southwestern Willow Flycatcher ( Empidonax traillii extimus ) breeding habitat. Although this enhancement was designed to benefit flycatchers, few flycatchers have inhabited the seep areas within the past several years; therefore, vireos were selected as a surrogate species to determine effects of the habitat enhancement. This report presents the second year of analyses of vireo and vegetation response to the artificial seeps. We sampled vegetation in two Seep sites and two Reference sites to determine the effects of a new water diversion dam that was completed in 2019 and two seep pumps that were installed to enhance surface water along the Santa Margarita River in 2019 and 2021. We measured higher total vegetation cover below 2 meters (m) at Seep sites than at Reference sites and lower total vegetation cover above 5 m at Seep sites than at Reference sites. Native herbaceous cover was also higher below 4 m at Seep sites than at Reference sites. Woody cover was lower above 5 m at Seep sites than at Reference sites. Soil moisture did not differ between Seep and Reference sites. The U.S. Geological Survey has been color banding Least Bell’s Vireos on Marine Corps Base Camp Pendleton since 1995. In 2021, we continued to color band and resight color banded Least Bell’s Vireos to evaluate adult site fidelity, between-year movement, and the effect of surface-water enhancement on vireo site fidelity and between-year movement. We banded 164 Least Bell's Vireos for the first time during the 2021 season. Birds banded included 3 adult vireos and 161 juvenile vireos. All adult vireos were banded with unique color combinations. The juvenile vireos (all nestlings) were banded with a single gold numbered federal band on the right leg. There were 52 Least Bell's Vireos banded before the 2021 breeding season that were resighted and identified on Base in 2021. Of these vireos, 45 were banded on Base, 6 were originally banded on the San Luis Rey River, and 1 was banded at Marine Corps Air Station, Camp Pendleton. Adult birds of known age ranged from 1 to at least 7 years old. Base-wide survival of vireos was affected by sex, age, and year. Males had a slightly but significantly higher survival rate than females. Adults had a higher survival rate than first-year vireos. Survival of both adults and first-year birds was high from 2007 to 2008 and from 2012 to 2013 and low from 2020 to 2021. The return rate of adult vireos to Seep or Reference sites ranged from 45 to 57 percent. Most returning adult vireos showed strong between-year site fidelity. Of the adults present in 2020 and 2021, 84 percent (94 percent of males; no females) returned to within 100 m of their previous territory. The average between-year movement for returning adult vireos was 0.1±0.2 kilometer (km). The average movement of first-year vireos detected in 2021 that fledged from a known nest on MCBCP in 2020 was 1.1±0.7 km. We monitored Least Bell's Vireo pairs to evaluate the effects of surface-water enhancement on nest success and breeding productivity. Vireos were monitored at two Seep sites and two Reference sites. Early in 2021, a seep was installed in a 2020 Reference site, which changed the status of this monitoring site from Reference to Seep. Nesting activity was monitored between April 5 and July 22 in 50 territories within the Seep and Reference sites (25 at Seep sites and 25 at Reference sites). All territories, except one, were occupied by pairs and all were fully monitored, meaning all nesting attempts were monitored at these territories. During the monitoring period, 97 nests (42 in Seep sites and 55 in Reference sites) were monitored. Breeding productivity was similar at the Seep site and Reference sites (3.6 and 3.4 young per pair, respectively), with 84 percent of Seep pairs and 88 percent of Reference pairs successfully fledging at least one young in 2021. Seep sites had a higher proportion of all eggs that hatched and also a higher proportion of nests with eggs that hatched than Reference sites. Seep sites and References sites had similar proportions of hatchlings that fledged and nests with hatchlings that fledged. According to the best model, daily nest survival in 2021 was higher in Seep sites than in Reference sites. Completed nests at the Seep site were more likely to be successful than nests at Reference sites in 2021. At Seep sites, 75 percent of nests fledged young, whereas 53 percent of nests at Reference successfully fledged young. Vireos at Reference sites had to expend more energy in extra nest-building and egg-laying to produce a similar number of young as vireos at Seep sites. Predation was believed to be the primary source of nest failure at both sites. Predation accounted for 100 percent and 83 percent of nest failures at Seep and Reference sites, respectively. Failure of the remaining nests was attributed to infertile eggs and other unknown causes. There were 11 plant species used as hosts for vireo nests in 2021. Successful vireo nests at Reference sites were further from the edge of host plants (closer to the center) and further from the edge of the nest plant clump than unsuccessful nests. Vireo nests at Seep sites were further from the edge of the host plant and the nest plant clump than vireo nests at Reference sites.

California↗

USGS2026

Distribution, abundance, breeding activities, and restoration efforts for the Southwestern Willow Flycatcher at Marine Corps Base Camp Pendleton, California—2025 Annual Report

Executive Summary The purpose of this report is to provide the Marine Corps with an annual summary of the distribution, abundance, and breeding activity of the endangered Southwestern Willow Flycatcher ( Empidonax traillii extimus ; flycatcher) and to present results of management actions implemented to attract flycatchers and enhance flycatcher habitat at Marine Corps Base Camp Pendleton (MCBCP, or Base). Surveys for the flycatcher were done on Base between May 6 and July 23, 2025. All MCBCP’s historically occupied riparian habitat (core survey area) was surveyed for flycatchers in 2025. None of the non-core survey areas were surveyed in 2025. No resident flycatchers were detected on Base in 2025. The one resident (female) present in 2024 did not return to the territory she occupied in 2024, and she was not detected within the historically occupied habitat surveyed in 2025. Eight transient Willow Flycatchers of unknown subspecies were observed on two of the five drainages surveyed in 2025: Las Flores Creek and the Santa Margarita River. No Willow Flycatchers were detected at Fallbrook, Pilgrim, or San Mateo Creeks. Transients in 2025 occurred in mixed willow and riparian scrub habitats, dominated by multiple willow species ( Salix spp. ). Exotic vegetation was recorded in most flycatcher locations and was dominant (cover of exotics greater than 50 percent) in more than half of all transient locations. The most common exotic plant in habitat used by flycatchers was poison hemlock ( Conium maculatum ). All six of the flycatchers that were observed closely enough to determine banding status were unbanded. Two measures were initiated in recent years to attract and retain resident breeding flycatchers on MCBCP: conspecific attraction using flycatcher song broadcasts and installation of artificial seeps to enhance flycatcher habitat. We surveyed plots with and without speakers that broadcast flycatcher vocalizations throughout the breeding season and detected two transient Willow Flycatchers within 20 meters of one speaker in 2025. We set up permanent vegetation sampling points surrounding artificial seeps and nearby sites without artificial seeps (Reference sites) to determine the effects of surface-water enhancement by seep pumps. Vegetation cover was highest near the ground and decreased with increasing height. Woody vegetation made up most of the cover at all height categories. Soil saturation in 2025 was higher at the sites near seeps than at the Reference sites and was associated with higher native herbaceous cover and lower non-native cover.

California↗

USGS2010

U.S. Geological Survey Science for the Wyoming Landscape Conservation Initiative-2009 Annual Report

This is the second report produced by the U.S. Geological Survey (USGS) for the Wyoming Landscape Conservation Initiative (WLCI) to detail annual work activities. The first report described work activities for 2007 and 2008; this report covers work activities conducted in 2009. Important differences between the two reports are that (1) this report does not lump all the Effectiveness Monitoring activities together as last year's report did, which will allow WLCI partners and other readers to fully appreciate the scope and accomplishments of those activities, and (2) this report does not include a comprehensive appendix of the background details for each work activity. In 2009, there were 29 ongoing or completed activities, and there were 5 new work activities conducted under the 5 original major multi-disciplinary science and technical assistance activities: (1) Baseline Synthesis; (2) Targeted Monitoring and Research; (3) Data and Information Management; (4) Integration and Coordination; and (5) Decisionmaking and Evaluation. New work included (1) developing a soil-quality index, (2) developing methods for assessing levels of and relationships between mercury and soil organic matter, and (3) ascertaining element source, mobility, and fate. Additionally, (4) remotely sensed imagery was used to assess vegetation as an indicator of soil condition and geology, and (5) an Integrated Assessment (IA) was initiated to synthesize what has been learned about WLCI systems to date, and to develop associated decision tools, maps, and a comprehensive report.

Open-File Report↗

USGS2011

U.S. Geological Survey Science for the Wyoming Landscape Conservation Initiative-2010 Annual Report

This is the third report produced by the U.S. Geological Survey (USGS) for the Wyoming Landscape Conservation Initiative (WLCI) to detail annual work activities. The first report described activities for 2007 and 2008, and the second report covered work activities for FY09. This third report covers work activities conducted in FY2010, and it continues the 2009 approach of reporting on all the individual activities to help give WLCI partners and other readers the full scope of what has been accomplished. New in this year's report is an additional section for each work activity that outlines the work planned for the following fiscal year. In FY2010, there were 35 ongoing/expanded, completed, or new projects conducted under the five major multi-disciplinary science and technical-assistance activities: (1) Baseline Synthesis; (2) Targeted Monitoring and Research; (3) Data and Information Management; (4) Integration and Coordination; and (5) Decisionmaking and Evaluation. The three new work activities were to (1) compile existing water data for the entire WLCI region and (2) develop regional curves (statistical models) for relating bankfull-channel geometry and discharge to drainages in the WLCI region, both of which will help guide long-term monitoring of water resources; and (3) initiate a groundwater-monitoring network to evaluate potential effects of energy-development activities on groundwater quality where groundwater is an important source of public/private water supplies. Results of the FY2009 work to develop methods for assessing soil organic matter and mercury indicated that selenium and arsenic levels may be elevated in the Muddy Creek Basin; thus, the focus of that activity was shifted in FY2010 to evaluate biogeochemical cycling of elements in the basin. In FY2010, two ongoing activities were expanded with the addition of more sampling plots: (a) the study of how greater sage-grouse (Centrocercus urophasianus) use vegetation-treatment areas (sites added to the Moxa Arch Natural Gas Development area) and (2) the study of cheatgrass (Bromus tectorum) occurrence in burn treatments of the Little Mountain Ecosystem. The activity that entails evaluating relationships between ungulate herbivory and fire on aspen (Populus tremuloides) recruitment also was expanded to include relationships between stand characteristics of and herbivory on aspen in various ecohydrological settings. The USGS continued compiling data and developing geospatial products from all of its WLCI activities to support (1) ranking and prioritizing of proposed conservation projects, (2) developing the WLCI Integrated Assessment, and (3) developing the WLCI 5-year Conservation Action Plan. Two activities were completed in FY2010: (1) the conceptual modeling and indicator selection for monitoring resource conditions across the WLCI region, and (2) the literature review on effects of oil and gas development in western regions of the United States, both of which are in the last stages of publication.

Open-File Report↗

USGS2014

U.S. Geological Survey Science for the Wyoming Landscape Conservation Initiative - 2013 Annual Report

This is the sixth report produced by the U.S. Geological Survey (USGS) for the Wyoming Landscape Conservation Initiative (WLCI) to detail annual activities conducted by USGS for addressing specific management needs identified by WLCI partners. In FY2013, there were 25 ongoing and new projects conducted by the USGS. These projects fall into 8 major categories: (1) synthesizing and analyzing existing data to describe (model and map) current conditions on the landscape; (2) developing models for projecting past and future landscape conditions; (3) monitoring indicators of ecosystem conditions and the effectiveness of on-the-ground habitat projects; (4) conducting research to elucidate the mechanisms underlying wildlife and habitat responses to changing land uses; (5) managing and making accessible the large number of databases, maps, and other products being developed; (6) helping to integrate WLCI outcomes with future habitat enhancement and research projects; (7) coordinating efforts among WLCI partners; and (8) providing support to WLCI decision-makers and assisting with overall evaluation of the WLCI program. The two new projects initiated in FY2013 address (1) important agricultural lands in southwestern Wyoming, and (2) the influence of energy development on native fish communities. The remaining activities entailed our ongoing efforts to compile data, model landscape conditions, monitor trends in habitat conditions, conduct studies of wildlife responses to energy development, and upgrade Web-based products in support of both individual and overall WLCI efforts. Milestone FY2013 accomplishments included completing the development of a WLCI inventory and monitoring framework and the associated monitoring strategies, protocols, and analytics; and initial development of an Interagency Inventory and Monitoring Database, which will be accessible through the Monitoring page of the WLCI Web site at http://www.wlci.gov/monitoring. We also completed the initial phase of the mountain shrub-mapping project in the Big Piney-La Barge mule deer winter range. Finally, a 3-year survey of pygmy rabbits in four major gas-field areas was completed and used to validate the pygmy rabbit habitat model/map developed earlier in the project. Important products that became available for use by WLCI partners included publication of USGS Data Series report (http://pubs.usgs.gov/ds/800/pdf/ds800.pdf) that compiles our WLCI land cover and land use data, which depict current and historical patterns of sage-grouse habitat in relation to energy development and will be used to pose “what-if” scenarios to evaluate possible outcomes of alternative land-use strategies and practices on habitat and wildlife. Another important FY2013 product was a journal article (http://aapgbull.geoscienceworld.org/content/97/6/899.full) that describes the Mowry Shale and Frontier formation, which harbors coalbed methane and shale gas resources in Wyoming, Colorado, and Utah, for use in future scenario-building work. We also produced maps and databases that depict the structure and condition of aspen stands in the Little Mountain Ecosystem, and then presented this information to the Bureau of Land Management, Wyoming Game and Fish Department, and other interested entities for supporting aspen-management objectives.

Open-File Report↗

USGS2015

U.S. Geological Survey science for the Wyoming Landscape Conservation Initiative—2014 annual report

This is the seventh report produced by the U.S. Geological Survey (USGS) for the Wyoming Landscape Conservation Initiative (WLCI) to detail annual activities conducted by the USGS for addressing specific management needs identified by WLCI partners. In FY2014, there were 26 projects, including a new one that was completed, two others that were also completed, and several that entered new phases or directions. The 26 projects fall into several categories: (1) synthesizing and analyzing existing data to identify current conditions on the landscape and using the data to develop models for projecting past and future landscape conditions; (2) monitoring indicators of ecosystem conditions and the effectiveness of on-the-ground habitat projects; (3) conducting research to elucidate the mechanisms underlying wildlife and habitat responses to changing land uses; (4) managing and making accessible the large number of databases, maps, and other products being developed; and (5) coordinating efforts among WLCI partners, helping them use USGS-developed decision-support tools, and integrating WLCI outcomes with future habitat enhancement and research projects. The new (completed) project was the development and publication of a public outreach piece for visitors of Fossil Butte National Monument. The final product was a USGS Fact Sheet that capitalized on previously collected elk-monitoring data to interpret the ecology of the Monument’s elk population and the importance of the Monument’s habitats to this highly visible wildlife species. One of the completed projects entailed developing and evaluating a synthetic approach to high-resolution satellite imagery for use in effectiveness monitoring, which culminated in a journal article. The other completed project was a coalescing of two similar tasks under data and information management that pertain to Web application development and the development of outreach and graphic products into a single integrated project that focuses on developing and maintaining/upgrading Web applications and other tools for visualizing, mapping, and using geospatial data. Major accomplishments for FY2014 included several publications, including Part B of an energy resources map that (with Part A) depicts coal, wind, oil, gas, oil shale, uranium, and solar energy production in the WLCI region. Two published works associated with sage-grouse included a Wildlife Monograph on prioritizing species’ habitats across large landscapes, multiple seasons, and novel areas (using sage-grouse in Wyoming as an example), and a USGS Data Series report that includes both the data used in the habitat-prioritization models and the habitat prioritization models developed for sage-grouse. Our Science Team also published a framework for conducting large, collaborative projects that rely on geospatial data, and a paper that describes the efficacy of fusing satellite data collected at various resolutions for measuring and monitoring vegetation changes. These products are all invaluable tools for maximizing the efficiency and effectiveness of managing species of concern, conducting future landscape-scale assessments, and monitoring status and trends of landscape conditions. Other highlights of FY2014 included a renewed effort to gather and analyze wildlife and habitat status and trend data for the WLCI Interagency Monitoring Database (IAMD) to assess long-term trends and cumulative effects associated with land-use and climate changes. Water-monitoring efforts included drilling four new groundwater-monitoring wells in the Green and New Fork River basins near the proposed Normally Pressured Lance Formation energy development, and continued data collection at established water-monitoring sites. Three additional wells were sampled as part of the Wyoming Groundwater Monitoring Network, bringing the total to 19 Network wells sampled in the WLCI region since 2010. Combined, these water-monitoring efforts can help to identify potential changes in water quality or levels that may result from land-use changes. Major terrestrial monitoring accomplishments included processing satellite imagery from 1985−2010 to develop a historical perspective of long-term vegetation changes, which can serve as a basis for monitoring current and future trends in sagebrush steppe. Such data are crucial tools for agencies tasked with sage-grouse management and conservation. The USGS WLCI Science Team also continued monitoring and testing methods for evaluating WLCI habitat treatments designed to promote aspen regeneration and enhance sage-grouse habitat, and to assess how those treatments influence invasive species distributions and ungulate herbivory. Highlights included analyzing field data collected to elucidate the relationships between sage-grouse habitat use and the proximity of energy infrastructure, and using new instruments to measure productivity responses of aspen woodlands to various factors. Numerous FY2014 accomplishments specifically addressed agency needs to manage and conserve Wyoming’s wildlife species of concern. A pygmy rabbit habitat model and Wyoming distribution map were completed to identify factors associated with rabbit habitat occupancy. Previous work on sage-grouse population dynamics was expanded to better understand the factors that drive long-term viability of sage-grouse populations and to develop a tool that helps to identify key factors limiting sage-grouse persistence in Wyoming. Field work and data analyses continued for elucidating the relationships between sagebrush songbird abundance and productivity, the intensity of energy development, and community dynamics of nest predators. For the mule deer study, mixed mountain shrublands important to migrating and wintering mule deer were mapped and delivered to WLCI partners. Additionally, the relationships between energy development and crucial winter habitat for mule deer were evaluated, and a new phase of work was implemented to better understand relationships between plant phenology and mule deer migration movements. Finally, initial analyses of data collected to evaluate fish-community composition in relation to habitat quality indicate that water quality, as measured by concentrations of hydrocarbons, water temperature, and others parameters, has been diminished in subwatersheds with higher levels of energy development. Overall, the outcomes and products of these wildlife studies contribute significantly to the information and tools needed for addressing effects of land-use changes on Wyoming’s species of concern. Finally, capabilities of the WLCI Web site and the USGS ScienceBase infrastructure were maintained and upgraded to help ensure access to and efficient use of all the WLCI data, products, assessment tools, and outreach materials that have been developed. Of particular note is the completion of three Web applications developed for mapping (1) the 1900−2008 progression of oil and gas development;(2) the predicted distributions of Wyoming’s Species of Greatest Conservation Need; and (3) the locations of coal and wind energy production, sage-grouse distribution and core management areas, and alternative routes for transmission lines within the WLCI region. Collectively, these applications tools provide WLCI planners and managers with powerful tools for better understanding the distributions of wildlife species and potential alternatives for energy development.

Wyoming↗

USGS2003

Cibola High Levee Pond Annual Report 2003. Interim Report

Bonytail and razorback sucker have once again spawned and produced swim-up larvae in Cibola High Levee Pond (CHLP). CHLP continues to support annual recruitment of bonytail while recent razorback sucker recruitment remains elusive. Thus far, razorbacks have experienced intermittent years of spawning success. Both native species were observed spawning on, or near, the riprap on the river levee. Razorbacks spawned from late January until mid-March over gravel and large cobble along the levee toe (2-3 m depth) and bonytail spawned along the levee shoreline during mid-April. Razorback suckers rapidly fin during the reproductive act, which flushes fines from the substrate and leaves gravel relatively clean. Bonytail on the other hand, appear to spawn over or on substrate that has been disturbed by beaver activity. Substrate scour or disturbance appears to be an important factor in spawning site selectiona?|

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USGS2021

Black abalone surveys at Naval Base Ventura County, San Nicolas Island, California—2020, annual report

The U.S. Geological Survey monitors a suite of intertidal black abalone sites at San Nicolas Island, California, in cooperation with the U.S. Navy, which owns the island. The nine rocky intertidal sites were established in 1980 to study the potential impact of translocated sea otters on the intertidal black abalone population at the island. The sites were monitored from 1981 to 1997, usually annually or biennially. Monitoring resumed in 2001 and has been completed annually since then. At the time of this report, the work is conducted by the Western Ecological Research Center’s Santa Cruz Field Station, Santa Cruz, California. The study sites became particularly important, from a management perspective, after a virulent disease decimated black abalone populations throughout southern California beginning in the mid-1980s. The disease, withering syndrome, was first observed on San Nicolas Island in 1992 and during the next few years, it reduced the population there by more than 99 percent. The species was subsequently listed as endangered under the Endangered Species Act in 2009. The subject of this report is the 2020 monitoring cycle of the sites and how the current status fits into the long-term data at San Nicolas Island. Since 2001, the monitored population has increased twelvefold to approximately 9.6 percent of the pre-disease level. This increase has resulted from generally higher levels of recruitment than seen in the first two decades of monitoring, punctuated by a few unexplained high recruitment events. Most of the population growth has been at two of the nine sites (sites 7 and 8). This pattern continued in 2020, but with increasing numbers at all sites and the highest number of abalone counted and measured island-wide since 1993. Recruitment rates have fallen since a peak in 2017, but 2020 continued to show moderate levels of additional recruitment. The distance between adjacent black abalone has decreased substantially since it was first consistently measured in 2005, potentially indicating that the abalone are close enough to one another to reproduce successfully. Sand burial can have devastating localized consequences to black abalone, but there is evidence suggesting that they may be able to escape periodic sand inundation if suitable refugia exist. These data suggest that monitoring can inform adaptive management of the resource by base resource managers.

California↗

USGS2009

Bull Trout Forage Investigations in Beulah Reservoir, Oregon - Annual Report for 2006

Beulah Reservoir on the north fork of the Malheur River in northeastern Oregon provides irrigation water to nearby farms and ranches and supports an adfluvial population of bull trout (Salvelinus confluentus), which are listed as threatened under the Endangered Species Act. Water management in Beulah Reservoir results in seasonal and annual fluctuations of water volume that may affect forage availability for bull trout. Because no minimum pool requirements currently exist, the reservoir is occasionally reduced to run-of-river levels, which may decimate forage fish populations and ultimately affect bull trout. We sampled fish and aquatic insects in Beulah Reservoir in the spring, before the annual drawdown of 2006, and afterward, in the late fall. We also collected samples 1.5 years after the reservoir was dewatered for three consecutive summers. Overall, the moderate drawdown of 2006 (32 percent of full pool) did not drastically alter the fish community in Beulah Reservoir. We did document, however, decreases in abundance and sizes of chironomids in areas of the reservoir that were frequently dewatered, increased catch rates of fish with gillnets, and decreases in population estimates for smaller fishes after drawdown. In 2006, after the dewaterings of 2002-04, species composition was similar to that prior to the dewaterings, but the size distributions of most species were biased toward small juvenile or subyearling fishes and larger fishes were rare. Our results indicate that repeated reservoir drawdown reduces aquatic insect forage for bull trout and probably affects forage fish populations at least temporarily. The high catch rates of juvenile fishes 1.5 years after consecutive dewaterings suggests good reproductive success for any remaining adult fish, and shows that the fish community in Beulah Reservoir is resilient to such disturbances. There is, however, a period of time after serious drawdowns before significant numbers of juvenile fishes start to appear in the reservoir. Because Beulah Reservoir experiences a wide variety of drawdown scenarios in consecutive years, the forage fish community may never reach a state of equilibrium.

Open-File Report↗

USGS2025

Black abalone surveys at Naval Base Ventura County, San Nicolas Island, California—2022 annual report

The U.S. Geological Survey monitors a suite of intertidal black abalone ( Haliotis cracherodii ) sites at San Nicolas Island, California, in cooperation with the U.S. Navy, which owns the island. The nine rocky intertidal sites were established in 1980 to study the potential effect of translocated southern sea otters ( Enhydra lutris nereis ) on the intertidal black abalone population at San Nicolas Island. The sites were monitored, typically annually or biennially, from 1981 to 1997. Monitoring resumed in 2001 and has been completed annually thereafter. Since 2018, the monitoring has been carried out by the U.S. Geological Survey Western Ecological Research Center. The study sites became particularly important from a management perspective after a virulent disease decimated black abalone populations throughout southern California beginning in the mid-1980s. The disease, withering syndrome, was first observed on San Nicolas Island in 1992, and during the next few years, withering syndrome reduced the black abalone population on San Nicolas Island by more than 99 percent. The black abalone was subsequently listed as endangered under the Endangered Species Act in 2009. The subject of this report is the 2022 survey of the sites and the status of the measured population of black abalone in comparison to long-term patterns (based on data collected since 1981) at San Nicolas Island. Between the years 2000 and 2022, the total monitored black abalone population on the island has grown from roughly 200 to more than 2,000, approximately a ten-fold increase following the disease-related decline. Since it was first consistently measured in 2005, the distance between adjacent black abalone has decreased substantially from approximately 50 centimeters to less than 15 centimeters, indicating that black abalone are sufficiently close together at several of the sites to reproduce successfully. The total black abalone count in 2022 was 2,156, which was 7.9 percent lower than the total count in 2020 but 6.6 percent higher than in 2021. There were increases and decreases among the sites and transects within each site in 2022, but six of the nine sites had higher counts than in the previous year. The 2022 count is one of the highest since 1993, second only to the 2020 count. In 2022, the annual recruitment rate, defined as the percentage of measured black abalone with a shell length of 3 centimeters or less, was the second highest recorded, only slightly less than in 2017.

California↗

USGS2022

Black Abalone surveys at Naval Base Ventura County, San Nicolas Island, California—2021, annual report

The U.S. Geological Survey monitors a suite of intertidal black abalone sites at San Nicolas Island, California, in cooperation with the U.S. Navy, which owns the island. The nine rocky intertidal sites were established in 1980 to study the potential effect of translocated sea otters on the intertidal black abalone population at the island. The sites were monitored from 1981 to 1997, usually annually or biennially. Monitoring resumed in 2001 and has been completed annually since then. Since 2018, the work has been carried out by the U.S. Geological Survey Western Ecological Research Center. The study sites became particularly important, from a management perspective, after a virulent disease decimated black abalone populations throughout southern California beginning in the mid-1980s. The disease, withering syndrome, was first observed on San Nicolas Island in 1992 and during the next few years, it reduced the population there by more than 99 percent. The species was subsequently listed as endangered under the Endangered Species Act in 2009. The subject of this report is the 2021 survey of the sites and how the measured population status compares to the long-term data (collected over several decades) at San Nicolas Island. During the last two decades, the total monitored black abalone population at the island has grown approximately ten-fold after the disease related decline, from about 200 to more than 2,000 abalone. Since it was first consistently measured in 2005, the mean distance between adjacent black abalone has decreased substantially from approximately 50 centimeters to less than 15 centimeters, indicating that abalone are close enough together at several of the sites to reproduce successfully. The 2021 counts were the first since 2016 to indicate a possible decline in the monitored population at San Nicolas Island. Although still more than ten times the population counted in 2001, counts on the transects dropped by 13.6 percent from the survey count in 2020. The most significant decline was the loss of 341 abalone, from the previous count of 547, on a transect that since 2002 had the highest count of all 44 transects. Between 2020 and 2021, there were increases and decreases at the sites and the transects at each site. Although the 2021 count was lower than the 2020 count, it was the second highest since 1997. Based on the number of small abalone counted, recruitment rates were similar to most years since 2008 and higher than the rates observed before the population declines resulting from withering syndrome.

California↗

USGS2017

U.S. Geological Survey—Energy and wildlife research annual report for 2017

Introduction Terrestrial and aquatic ecosystems provide valuable services to humans and are a source of clean water, energy, raw materials, and productive soils. The Nation’s food supply is more secure because of wildlife. For example, native pollinators enhance agricultural crops, and insect-eating bats provide pest control services worth billions of dollars to farmers annually. Fish and wildlife are also vital to a vibrant outdoor recreation and tourism industry. Recreational activities, such as hunting, shooting, boating, and angling, generated \$1.1 billion in excise taxes paid to State wildlife agencies in 2017. National parks, wildlife refuges, and monuments accounted for $35 billion in economic output and 318,000 jobs nationwide in 2016. Additional economic benefits are generated from the use and enjoyment of wildlife in State-owned lands and waters. Although the United States is rich in natural resources, human activity continues to place new pressures on fish and wildlife and the habitats they rely on. The United States became the world’s top producer of petroleum and natural gas products in 2012, surpassing Russia’s natural gas production levels in 2009 and Saudi Arabia’s petroleum production in 2013. The U.S. Energy Information Administration projects that the demand for liquid fuel, natural gas, and renewable energy will show strong growth in the next 20 years. Wind energy has demonstrated consistent growth since 2007 with now more than 53,000 wind turbines contributing to power grids in 41 States, Guam, and Puerto Rico. Solar energy has seen rapid growth since 2013 and made up nearly one-third of the total electricity generation additions in 2016. Yet as our Nation works to advance energy security and sustain wildlife, some conflicts have surfaced. Impacts of an expanding energy infrastructure include fragmentation and loss of habitat as well as mortality of birds, bats, fish, and other animals from interactions with energy generation facilities. Because energy development can often occur in wildlife habitats, ecological science can help guide project siting and operational decisions to areas that present the lowest risk to wildlife and energy developers. To address these challenges and make the most of new opportunities, the U.S. Geological Survey is producing innovative science to develop workable solutions that can help sustain wildlife and the habitat they rely upon, while allowing informed development.

Circular↗

USGS2026

Black abalone surveys at Naval Base Ventura County, San Nicolas Island, California—2023 annual report

The U.S. Geological Survey monitors a suite of intertidal black abalone ( Haliotis cracherodii ) sites at San Nicolas Island, California, in cooperation with the U.S. Navy, which owns the island. The nine rocky intertidal sites were established in 1980 to study the potential effect of translocated sea otters on the intertidal black abalone population at the island. The sites were monitored from 1981 to 1997, typically annually or biennially. Monitoring resumed in 2001 and has been completed annually thereafter. Since 2018, the work has been carried out by the U.S. Geological Survey Western Ecological Research Center. The study sites became particularly important, from a management perspective, after a virulent disease decimated black abalone populations throughout southern California beginning in the mid-1980s. The disease, withering syndrome ( Candidatus Xenohaliotis californiensis ), was first observed on San Nicolas Island in 1992 and over the next few years, withering syndrome reduced the black abalone population on San Nicolas Island by more than 99 percent. In 2009, the black abalone subsequently was listed as endangered under the Endangered Species Act. The subject of this report is the 2023 survey of the sites and the status of the measured population in comparison to long-term patterns (based on data collected since 1981) at San Nicolas Island. Between the years 2000 and 2023, the total monitored black abalone population at the island has grown from roughly 200 to more than 2,500 abalone following disease-related decline. Since it was first consistently measured in 2005, the average distance between adjacent black abalone has decreased substantially from approximately 50 centimeters to less than 15 centimeters, indicating that abalone are sufficiently close together at several of the sites to reproduce successfully. The total abalone count in 2023 was 2,570, which was 19.2 percent higher than in 2022 and the highest count since 1993. All nine sites had higher counts in 2023 than in the previous year. Over 25 percent of the black abalone counted in 2023 were classified as recruits, defined as having a shell length of 3 centimeters or less.

California↗

USGS2013

Snake River fall Chinook salmon life history investigations: Annual report 2011 (April 2011 - March 2012)

Executive Summary Chapter One – This chapter was published in the Transactions of the American Fisheries Society in 2012. We conducted a three-year radiotelemetry study in the lower Snake River to answer the questions: do fall Chinook salmon juveniles pass dams during winter when bypass systems and structures designed to prevent mortality are not operated; does downstream movement rate vary annually, seasonally, and from reservoir to reservoir; and, what are some of the factors that contribute to annual, seasonal, and spatial variation in downstream movement rate? Fall Chinook salmon juveniles moved downstream up to 169 km and fast enough (7.5 km/d) such that large percentages (up to 93%) of the fish passed one or more dams during winter. Mean downstream movement rate varied annually (9.2-11.3 km/d), increased from winter (7.5 km/d) to spring (16.4 km/d), and increased (6.9-16.8 km/d) as fish moved downstream from reservoir to reservoir. Fish condition factor at tagging explained some of the annual variation ( P ≤ 0.01) in downstream movement rate, whereas water particle velocity ( P ≤0.0001) and temperature ( P ≤0.0001) explained portions of the seasonal variation. An increase in migrational disposition as fish moved downstream helped explain the spatial variation ( P =0.05-0.07). The potential cost of winter movement might be reduced survival due to turbine passage when the bypass systems and spillway passage structures are not operated. Efforts to understand and increase passage survival of winter migrants in large impoundments might help to rehabilitate some imperiled anadromous salmonid populations. Chapter Two – Natural juvenile fall Chinook salmon in the Snake and Clearwater rivers exhibit two life history strategies. “Ocean-type” fish migrate out to the ocean in their first summer of life as subyearlings, but “reservoir-type” fish delay seaward migration during the summer, and some overwinter in reservoirs before continuing their migration the following spring as yearlings. Earlier emerging fish produced in the Snake River tend to adopt the ocean-type life history whereas many of the later emerging fish from the Clearwater River tend to adopt the reservoirtype life history. The underlying cause of the reservoir-type life history is poorly understood, but we believe there may be link to physiological development. We used traditional markers of the parr-smolt transformation (smoltification), including gill Na + /K + -ATPase activity and thyroid hormone levels, along with gene expression microarrays to assess the development of ocean-type juvenile fall Chinook salmon and then compared it to that of juvenile fall Chinook salmon from the Clearwater River. We showed that parr in the Snake River are physiologically distinct from actively-migrating smolts but smolts migrating early and late in the summer and fall are physiologically similar. Juvenile fall Chinook salmon collected from the Clearwater River were similar in size to early-migrating smolts in the Snake River but were most physiologically similar to Snake River parr. Genes differentially expressed between Snake River parr and smolts and between fish from the Clearwater River and smolts from the Snake River were involved in the cell cycle, steroid metabolism and other metabolic pathways, and DNA repair and packaging. Many of the genes differentially expressed in these comparisons had expression patterns that correlated with gill Na + /K + -ATPase activity, suggesting that they were related to smoltification and migration status. Chapter Three – Natural subyearlings produced in the Clearwater River are exposed to cool (~10-12°C) temperatures when water is released from Dworshak Reservoir for summer flow augmentation. Total dissolved gas (TDG) levels range from 100-110% in the lower Clearwater iv River. When fish move into the Snake River, they encounter temperatures up to 24°C at the surface which have the potential to incur gas bubble disease (GBD) in fish as dissolved gases in their bodies expand under warmer temperatures. This may result in both direct and indirect mortality, but this situation has been little studied. We conducted laboratory experiments to examine subyearling mortality rates and incidence and severity of GBD in fish that were moved between waters that varied in TDG and temperature. Fish experienced significant mortality only at temperatures of 25°C, which increased with exposure time. However there was no significance difference in mortality between fish acclimated to 100% TDG and 110% TDG. Fish that died did show signs of GBD. Generally, signs of GBD such as bubbles in the lateral line and unpaired fins were higher in fish acclimated at 110% TDG than in fish acclimated at 100% TDG, but there were few trends related to exposure temperature. Field measurements of TDG showed that TDG ranged from about 100% to 122.5% at some locations. Generally, TDG fluctuated daily, up to 8% during August and early September, and was highest late in the afternoon and lowest in the early morning. Laboratory results and field monitoring demonstrated that emigrating juvenile salmon can potentially be at risk from elevated temperatures, TDG, and GBD albeit to an unknown extent, which may increase their vulnerability to predation. Chapter Four – We conducted monthly beam trawling in Lower Granite and Little Goose reservoirs to describe the seasonal abundance of benthic epifauna that are potentially important as prey to juvenile fall Chinook salmon. The predominant taxa collected were Siberian prawns, the opossum shrimp Neomysis mercedis , and the amphipod Corophium sp. Prawns were relatively abundant at shallow sites in both reservoirs in June, but were more abundant at deep sites in lower and middle reservoir reaches in autumn. Prawn densities were commonly <0.2/m2. Prawn length-frequency data indicated that there were at least two size classes. Juvenile prawns present in shallow water more often than adult prawns, which were generally only found in deep water by autumn. Ovigerous prawns had an average of 171 eggs, which represented about 11.5% of their body weight. Limited diet analyses suggested that prawns consumed Corophium , Neomysis , and aquatic insects. Neomysis dominated all catches both in terms of abundance and biomass, and they were more abundant in Lower Granite compared to Little Goose reservoir. Neomysis were more abundant at shallow sites than at deep sites. Corophium were present in our collections but were never abundant, probably because our trawl was not effective at capturing them. The caloric content of prawns (4,782 Kcal), Neomysis (4,962 Kcal), and Corophium (4,926 Kcal) indicates that these prey would be energetically profitable for juvenile salmon. Subyearling fall Chinook salmon prey heavily on Neomysis and Corophium at times, but the importance of prawns as prey is uncertain.

Oregon, Washington↗

USGS2020

Black abalone surveys at Naval Base Ventura County, San Nicolas Island, California: 2019, annual report

The U.S. Geological Survey Western Ecological Research Center’s Santa Cruz Field Station, Santa Cruz, California, has been funded by the U.S. Navy to continue monitoring a suite of intertidal black abalone sites at San Nicolas Island, California. The nine rocky intertidal sites were established in 1980 by Glenn VanBlaricom (then of the U.S. Fish and Wildlife Service) to study the potential impact of translocated sea otters on the intertidal black abalone population at the island. The sites were monitored from 1981 to 1997, usually annually or semi-annually. Monitoring resumed in 2001, and regular annual monitoring cycles have been conducted at the sites since then. The study sites became particularly important, from a management perspective, after a virulent disease decimated black abalone populations throughout southern California beginning in the mid-1980s. The disease, withering syndrome, was first observed on San Nicolas Island in 1992 and during the next few years reduced the population there by approximately 99 percent. The species was subsequently listed as endangered under the Endangered Species Act in 2009. The subject of this report is the 2019 monitoring cycle of the sites and how the current status fits into the long-term data at San Nicolas Island. Since 2001, the monitored population has increased nearly tenfold to approximately 8.7 percent of the pre-disease level. This increase has resulted from generally higher levels of recruitment than seen in the first two decades of monitoring, punctuated by a few high recruitment events. Most of the population growth has been at two of the nine sites (sites 7 and 8). This pattern continued in 2019 with increasing numbers at sites 7 and 8 and the highest number of abalone counted and measured island-wide since 1996. However, counts declined at six of the sites during the last year and the increases in counts at sites 7 and 8 barely offset these losses. Recruitment rates have fallen since a peak in 2017 but 2019 continued to show some additional recruitment. The distance between adjacent black abalone, a metric relevant to potential reproduction, has decreased substantially since it was first consistently measured in 2005. Although sand burial can have devastating localized consequences to black abalone, the sand cover data we collected was not sufficient to suggest an obvious temporal or site-based pattern to sedimentation, and there is no indication that this was a factor in any of the declines recorded in 2019. Continued monitoring of these sites can provide island biologists with species trends to aid in adaptive management of the resource.

California↗

USGS2024

Distribution, abundance, and breeding activities of the Southwestern Willow Flycatcher at Marine Corps Base Camp Pendleton, California—2022 annual report

Executive Summary Surveys for the endangered Southwestern Willow Flycatcher ( Empidonax traillii extimus ) were done at Marine Corps Base Camp Pendleton (MCBCP or “Base”), California, between May 9 and July 20, 2022. All of MCBCP’s historically occupied riparian habitat (core survey area) was surveyed for flycatchers in 2022. None of the non-core survey area was surveyed in 2022. Eight transient Willow Flycatchers of unknown subspecies were observed on three of the five drainages surveyed in 2022. Willow Flycatchers were not detected at Fallbrook or Pilgrim Creeks. Transients occurred in a range of habitat types, including mixed willow (Salix spp.) riparian, riparian scrub, and upland scrub habitat. Exotic vegetation, primarily poison hemlock ( Conium maculatum ), was present in most of the flycatcher locations. In 2022, for the second time since monitoring began in 2000, resident Southwestern Willow Flycatchers were not detected on Base. The decline was not isolated to MCBCP; similar declines have been documented across California in recent years. The one uniquely banded adult female flycatcher present during the 2021 breeding season did not return to MCBCP in 2022. None of the transients observed during surveys were seen to carry bands. From 2000 to 2022, adult annual survival of Southwestern Willow Flycatchers on MCBCP was 60±3 percent, whereas first-year survival was 20±3 percent. A conspecific attraction study was initiated on Base in 2018 and repeated annually through 2022; flycatchers were not observed near automated playback units in 2022.

California↗

USGS2020

Kelp forest monitoring at Naval Base Ventura County, San Nicolas Island, California: Fall 2017 and Spring 2018, Fourth Annual Report

To assess and track changes to the rocky subtidal communities surrounding San Nicolas Island, the U.S. Navy entered into an agreement with the U.S. Geological Survey (USGS) in 2014 to conduct an ecological monitoring program at several sites around the island. Four permanent sites—Nav Fac 100, West End, Dutch Harbor, and Daytona 100—were established. The sites were based on ones that had been monitored since 1980 by USGS and were combined or expanded for better comparability with monitoring programs conducted at the other California Channel Islands. At the sites, scientists from USGS and our cooperator, the University of California, Santa Cruz, measured bottom cover of algae and sessile invertebrate species in quadrats, counted and sized fish on swimming transects, and counted a suite of kelps and invertebrates on benthic band transects. Holdfast diameter and number of stipes of giant kelp ( Macrocystis pyrifera ) were recorded on these transects, and size data were collected for urchins, sea stars, and shelled mollusks. Bottom temperatures were recorded at hourly intervals by archival data loggers that were deployed at the sites. This report focuses primarily on data collected in fall 2017 and spring 2018 and makes comparisons with data collected in previous years, beginning in fall 2014. Nav Fac 100 is a site with a relatively low benthic profile, situated on the north side of San Nicolas Island. It was previously urchin dominated but underwent a dramatic decline in purple sea urchins in 2015 and 2016. Since then, macroalgae has become more prevalent as both annual brown algae, such as Dictyota, and perennials (for example, Cystoseira ) have become established. The invasive brown alga Sargassum horneri has also become established. West End, on the southwest side of the island, also lacks much bottom relief but has more crevice habitat associated with boulders. It remains dominated by kelps and red algae, but red algae have decreased recently. Dutch Harbor, on the south side, has many high relief rocky reefs and had the greatest fish and non-motile invertebrate densities. It remains the most stable of the sites. Daytona 100, on the southeast side, has moderate relief and has remained a patchwork of kelp and urchin dominated areas with moderate fish density. The main change at the sites during the last 4 years was the decline in urchin numbers at Nav Fac 100. There was storm-related mortality and subsequent recruitment in the M. pyrifera population at several of the sites in both 2016 and 2017. The winter of 2018, however, was relatively mild, with less destructive storm-related disturbance. The invasive brown alga S. horneri , first seen at San Nicolas Island at Nav Fac 100 in fall 2015, has become firmly established there during the last 2 sampling years. Finally, moderate increases were observed in purple urchin densities at all sites this spring. Long-term data are presented to illustrate trends and changes over the past three decades. Results indicate continued monitoring to evaluate ecosystem effects from perturbations owing to natural processes and anthropomorphic factors, including recovery of the sea otter population, changes in fisheries, invasive species and changing environmental conditions, could be valuable to inform managers’ decision-making.

California↗