Geology Reports⌕ Search

SEARCH · Geology Reports

Results for “Trends”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 973 records · Page 54Linked to original sources
USGS1999

External quality-assurance results for the National Atmospheric Deposition Program/National Trends Network, 1995-96

The U.S. Geological Survey operated four external quality-assurance programs for the National Atmospheric Deposition Program/National Trends Network (NADP/NTN) in 1995 and 1996: the intersite-comparison program, the blind-audit program, the interlaboratory- comparison program, and the collocated-sampler program. The intersite-comparison program assessed the precision and bias of pH and specific-conductance determinations made by NADP/NTN site operators. The analytical bias introduced during routine handling, processing, and shipping of wet-deposition samples and precision of analyte values was estimated using a blind-audit program. An interlaboratory-comparison program was used to evaluate differences between analytical results and to estimate the analytical precision of five North American laboratories that routinely analyzed wet deposition. A collocated-sampler program estimated the precision of the overall precipitation collection and analysis system from initial sample collection through final storage of the data. Results of two intersite-comparison studies completed in 1995 indicated 94.6 and 94.4 percent of the onsite pH determinations met the NADP/NTN accuracy goals, whereas 97.2 and 98.3 percent of the specific-conductance determinations were within the established limits. The percentages of onsite determinations that met the accuracy goals in 1996 were slightly less for both pH and specific-conductance than in 1995. In 1996, 93.2 and 87.5 percent of onsite pH determinations met the accuracy goals, whereas the percentage of onsite specific-conductance measurements that met the goals was 93.9 and 94.9 percent.The blind audit program utilizes a paired sample design to evaluate the effects of routine sample handling, processing and shipping on the chemistry of weekly precipitation samples. The portion of the blind audit sample subject to all of the normal onsite handling and processing steps of a regular weekly precipitation sample is referred to as the bucket portion, whereas the portion receiving only minimal handling is referred to as the bottle portion. Throughout the report, the term positive bias in regard to blind-audit results indicates that the bucket portion had a higher concentration than the bottle portion. The paired t-test of 1995 blind-audit data indicated that routine sample handling, processing, and shipping introduced a very small positive bias (a=0.05) for hydrogen ion and specific conductance and a slight negative bias (a =0.05) for ammonium and sodium. In 1995, the median paired differences between the bucket and bottle portions ranged from -0.02 milligram per liter for both ammonium and nitrate to +0.002 milligram per liter for calcium. Although the paired t-test indicated a very small positive bias for hydrogen ion, the median paired difference between the bucket and bottle portions was 0.00 microequivalents per liter, whereas for specific conductance, the median paired difference between the bucket and bottle portions was 0.200 microsiemens per centimeter in 1995. The paired t-test of blind-audit results in 1996 indicated statistically significant bias for 6 of the 10 analytes. Only chloride, nitrate, hydrogen ion, and specific conductance were not biased in 1996. However, the magnitude of the bias in 1996 was very small and only of limited importance from the viewpoint of an analytical chemist or data user. The median paired differences between the bucket and bottle portions ranged from -0.02 milligram per liter for both ammonium and chloride to +0.006 milligram per liter for calcium. For hydrogen ion, the median paired difference between the bucket and bottle portions was -0.357 microequivalent per liter; for specific conductance, the median paired difference between the bucket and bottle portions was 0.00 microsiemens per centimeter in 1996. Surface-chemistry effects due to different amounts of precipitation contacting the sample collection and shipping container surfac

Water-Resources Investigations Report↗
USGS1999

Water resources of Monroe County, New York, water years 1989-93, with emphasis on water quality in the Irondequoit Creek basin: Part 2. Atmospheric deposition, ground water, streamflow, trends in water quality, and chemical loads to Irondequoit Bay

Irondequoit Creek, which drains 169 square miles in the eastern part of Monroe County, has been recognized as a source of contaminants that contribute to the eutrophication of Irondequoit Bay on Lake Ontario. The discharge from sewage-treatment plants to the creek and its tributaries was eliminated in 1979 by diversion to another wastewater-treatment facility, but sediment and nonpoint-source pollution remain a concern. This report presents data from five surface-water sites in the Irondequoit Creek basin. Irondequoit Creek at Railroad Mills, East Branch Allen Creek, Allen Creek near Rochester, Irondequoit Creek at Blossom Road, and Irondequoit Creek at Empire Boulevard, to supplement published data from 1984-88. Data from Northrup Creek, which drains 11.7 square miles in western Monroe County, provide information on surface-water quality west of the Genesee River. Also presented are water-level and water-quality data from 12 observation-well sites in Ellison and Powdermill Parks and atmospheric-deposition data from 1 site (Mendon Ponds). Concentrations of several chemical constituents in streams of the Irondequoit Creek basin showed statistically significant trends during 1989-93. Concentrations of total suspended-solids and volatile suspended-solids in Irondequoit Creek at Blossom Road decreased 13.5 and 12.5 percent per year, respectively, and those at Empire Boulevard decreased 33.5 and 22 percent per year, respectively. Concentrations of ammonia plus organic nitrogen increased 17.6 percent per year at one site in the basin, but decreased 8.5 and 22.3 percent per year at two sites. Nitrite plus nitrate decreased at only one site (3.5 percent per year). Concentrations of total phosphorus increased at two sites (about 7 percent per year) and decreased at two other sites (7.6 and 29.9 percent per year), and orthophosphate concentrations increased at one site (10.8 percent per year). Dissolved chloride increased at three sites (1.7 to 10.9 percent per year), and dissolved sulfate decreased at one site (2.1 percent per year) and increased at one site (6.8 percent per year). Median concentrations of constituents were significantly lower in atmospheric deposition than in streamflow, although annual deposition of ammonia nitrogen, nitrite plus nitrate, total phosphorus, and orthophosphate in the basin exceeded the amounts removed by streamflow. Atmospheric deposition of chloride and sulfate, by contrast, represented only 1 and 12 percent, respectively, of the loads transported by Irondequoit Creek (Blossom Road site). Comparison of water-quality data from the Allen Creek site and Irondequoit Creek at Blossom Road from water years 1989-93 with corresponding data from 1984-88 indicates significant changes in median concentrations of several constituents. The concentration of dissolved chloride increased at Blossom Road and was unchanged at Allen Creek, whereas sulfate decreased at both sites. Concentrations of ammonia plus organic nitrogen, and nitrite plus nitrate, were significantly lower during 1989-93 than during 1984-88 at both sites. Total phosphorus concentration was lower during 1984-88 than during 1989-93 at Blossom Road but showed no change at Allen Creek, and orthophosphate concentration for 1989-93 was lower than in 1984-88 at both sites. Comparison of chemical loads in atmospheric deposition also indicates significant changes in many constituents. Five-year-mean loads of sodium, sulfate, and lead in atmospheric deposition for 1989-93 exceeded those for 1984-88, whereas 5-year-mean loads of calcium, magnesium, potassium, chloride, nitrite plus nitrate, ammonia nitrogen, and orthophosphate for 1989-93 were lower than in 1984-88. The changes in surface-water quality resulted from several factors within the basin, including land-use changes, annual and seasonal variations in streamflow, and year-to-year variations in the application of deicing salts on area roads. Statistical analyses of long-term (9 years or more) flow records of three unregulated streams in Monroe County indicate that annual mean flows for water years 1989- 93 were in the normal range (20th- to 80th-percentile). The greatest mean annual flow in this period-about 140 percent of normal at Irondequoit Creek and Black Creek-occurred in 1993, but the annual mean flow for that water year at Allen Creek was only 98 percent of normal. The lowest annual mean flows of these streams-ranging from 75 percent of normal to 93 percent of normal-occurred in 1989. The average annual mean flows for these streams for 1989-93 was 104 percent of normal, and that for 1984-88 was normal.

New York↗
USGS1985

Water quality of North Carolina streams – Water-quality characteristics for selected sites on the Cape Fear River, North Carolina, 1955-80 – Variability, loads, and trends of selected constituents

Historical water-quality data collected by the U.S. Geological Survey from the Cape Fear River at Lock 1, near Kelly, North Carolina, show increasing concentrations of total-dissolved solids, specific conductance, sulfate, chloride, nitrite plus nitrate nitrogen, magnesium, sodium, and potassium during the past 25 years. Silica and pH show decreasing trends during the same 1957-80 period. These long-term changes in water quality are statistically related to increasing population in the basin and especially to manufacturing employment. Comparisons of water-quality data for present conditions with estimated natural conditions indicate that over 50 percent of the loads of most major dissolved substances in the river at Lock 1 are the result of development impacts in the basin. Over 80 percent of the nutrients plus nitrate nitrogen, ammonia nitrogen, and total phosphorus presently in the streams originate from development. At four sampling stations on the Cape Fear River and its tributaries, recent water-quality data show that most constituents are always within North Carolina water-quality standards and Environmental Protection Agency water-quality criteria. However, iron, manganese and mercury concentrations usually exceed standards.

North Carolina↗
USGS2020

Amphibian chytrid prevalence on boreal toads in SE Alaska and NW British Columbia: Tests of habitat, life stages, and temporal trends

Tracking and understanding variation in pathogens such as Batrachochytrium dendrobatidis ([Bd]), which causes amphibian chytridiomycosis and has caused population declines globally, is a priority for many land managers. However, there has been relatively little sampling of amphibian communities at high latitudes. We used skin swabs collected during 2005–2017 from boreal toads (Anaxyrus boreas; N = 248), in southeast Alaska (USA; primarily in Klondike Gold Rush National Historical Park [KLGO]) and northwest British Columbia (Canada) to determine how Bd prevalence varied across life stages, habitat characteristics, local species richness, and time. Across all years, Bd prevalence peaked in June and was >3 times greater for adult toads (37.5%) vs. juveniles and metamorphs (11.2%). Bd prevalence for toads in the KLGO area, where other amphibian species are rare or absent, was highest from river habitats (55.0%), followed by human-modified upland wetlands (32.3%) and natural upland wetlands (12.7%) — the same rank-order these habitats are used for toad breeding. No Columbia spotted frogs (N = 12) or wood frogs (N = 2) from the study area tested Bd-positive, although all were from an area of low host density where Bd has not been detected. Prevalence of Bd on toads in the KLGO area decreased during 2005–2015. This trend from a largely single-species system may be encouraging or concerning, depending on how Bd is affecting vital rates, and emphasizes the need to understand effects of pathogens before translating disease prevalence into management actions.

Southeastern Alaska, Northwestern British Columbia↗
USGS2021

Embryo deformities and nesting trends in Kemp’s ridley sea turtles Lepidochelys kempii before and after the Deepwater Horizon oil spill

Kemp’s ridley sea turtles Lepidochelys kempii were disproportionately affected by the Deepwater Horizon (DWH) oil spill, which began on 20 April 2010. Embryo deformities were documented in inviable L. kempii eggs before (2008-2010) and after (2011-2013) the DWH spill in 2 Texas (USA) nesting areas (Upper Texas Coast and Padre Island National Seashore). Additional nesting trends, including clutch size and hatching success, were also investigated. Total and late-stage embryo deformity prevalence were 1.5 times greater after 2010 than before, but low in all nesting seasons (mean ± SD: 0.7 ± 8.5% total; 0.6 ± 8.0% late-stage) and did not differ between locations. Craniofacial and carapace deformities were the most frequently observed deformity types. Documented nests in both areas declined in 2010 relative to previous years, ending an exponential increase observed beginning in 1995. Clutch size remained consistent before and after the spill. Hatching success averaged 87.0 ± 33.3% in all years, but no effects from DWH were determined. Collectively, these data represent useful benchmarks against which to judge impacts of future crude oil spills and other catastrophic events.

Texas↗
USGS2008

Region-wide trends of nesting ospreys in northwestern Mexico: a three-decade perspective

We used a double-sampling technique (air plus ground survey) in 2006, with partial double coverage, to estimate the present size of the Osprey (Pandion haliaetus) nesting population in northwestern Mexico (coastal Baja California, islands in the Gulf of California, and coastal Sonora and Sinaloa). With the exception of Natividad, Cedros, and San Benitos islands along the Pacific coast of Baja California (all three excluded from our coverage in 2006 due to fog), this survey was a repeat of previous surveys conducted by us with the same protocol in 1977 and 1992/1993, allowing for estimates of regional population trends. The minimum population estimate for the area we surveyed in 2006 was 1343 nesting pairs, an 81% increase since 1977, but only a 3% increase since 1992/1993. The population on the Gulf side of Baja California generally remained stable during the three surveys (255, 236, and 252 pairs, respectively). The population of the Midriff Islands (Gulf of California in the vicinity of 29°N latitude) remained similar from 1992/1993 (308 pairs) to 2006 (289 pairs), but with notable population changes on the largest two islands (Guardian Angel: 45 to 105 pairs [133% increase]; Tiburón: 164 to 109 pairs [34% decrease]). The minimum estimated Osprey population on the Sonora mainland decreased in a manner similar to adjacent Isla Tiburón, i.e., by 26%, from 214 pairs in 1993 to 158 pairs in 2006. In contrast, the population in coastal Sinaloa, which had increased by 150% between 1977 and 1993, grew again by 58% between 1993 and 2006, from 180 to 285 pairs. Our survey confirmed previously described patterns of rapid population changes at a local level, coupled with apparent shifts in spatial distribution. The large ground-nesting population that until recently nested on two islands in San Ignacio Lagoon ( Pacific Ocean side, Baja California) was no longer present on the islands in 2006, but an equivalent number of pairs were found to the north and south of the lagoon, nesting in small towns and along adjoining overhead electric lines, with no overall change in population size for that general area (198 pairs in 1992; 199 in 2006). Use of artificial nesting structures was 4.3% in 1977 and 6.2% in 1992/1993, but jumped to 26.4% in 2006. Use of poles that support overhead electric lines poses a risk of electrocution to Ospreys and also causes power outages and fires. We recommend modification of these poles to safely accommodate Osprey nests, as has been successfully accomplished in many countries.

Journal of Raptor Research↗
USGS2017

Assessment of thermal maturity trends in Devonian-Mississippian source rocks using Raman spectroscopy: Limitations of peak-fitting method

The thermal maturity of shale is often measured by vitrinite reflectance (VRo). VRo measurements for the Devonian–Mississippian black shale source rocks evaluated herein predicted thermal immaturity in areas where associated reservoir rocks are oil-producing. This limitation of the VRo method led to the current evaluation of Raman spectroscopy as a suitable alternative for developing correlations between thermal maturity and Raman spectra. In this study, Raman spectra of Devonian–Mississippian black shale source rocks were regressed against measured VRo or sample-depth. Attempts were made to develop quantitative correlations of thermal maturity. Using sample-depth as a proxy for thermal maturity is not without limitations as thermal maturity as a function of depth depends on thermal gradient, which can vary through time, subsidence rate, uplift, lack of uplift, and faulting. Correlations between Raman data and vitrinite reflectance or sample-depth were quantified by peak-fitting the spectra. Various peak-fitting procedures were evaluated to determine the effects of the number of peaks and maximum peak widths on correlations between spectral metrics and thermal maturity. Correlations between D-frequency, G-band full width at half maximum (FWHM), and band separation between the G- and D-peaks and thermal maturity provided some degree of linearity throughout most peak-fitting assessments; however, these correlations and those calculated from the G-frequency, D/G FWHM ratio, and D/G peak area ratio also revealed a strong dependence on peak-fitting processes. This dependency on spectral analysis techniques raises questions about the validity of peak-fitting, particularly given the amount of subjective analyst involvement necessary to reconstruct spectra. This research shows how user interpretation and extrapolation affected the comparability of different samples, the accuracy of generated trends, and therefore, the potential of the Raman spectral method to become an industry benchmark as a thermal maturity probe. A Raman method devoid of extensive operator interaction and data manipulation is quintessential for creating a standard method.

Frontiers in Energy Research↗
USGS2021

Long-term trends in regional wet mercury deposition and lacustrine mercury concentrations in four lakes in Voyageurs National Park

Although anthropogenic mercury (Hg) releases to the environment have been substantially lowered in the United States and Canada since 1990, concerns remain for contamination in fish from remote lakes and rivers where atmospheric deposition is the predominant source of mercury. How have aquatic ecosystems responded? We report on one of the longest known multimedia data sets for mercury in atmospheric deposition: aqueous total mercury (THg aq ), methylmercury (MeHg aq ), and sulfate from epilimnetic lake-water samples from four lakes in Voyageurs National Park (VNP) in northern Minnesota; and total mercury (THg) in aquatic biota from the same lakes from 2001–2018. Wet Hg deposition at two regional Mercury Deposition Network sites (Fernberg and Marcell, Minnesota) decreased by an average of 22 percent from 1998–2018; much of the decreases occurred prior to 2009, with relatively flat trends since 2009. In the four VNP lakes, epilimnetic MeHg aq concentrations declined by an average of 44 percent and THg aq by an average of 27 percent. For the three lakes with long-term biomonitoring, temporal patterns in biotic THg concentrations were similar to patterns in MeHg aq concentrations; however, biotic THg concentrations declined significantly in only one lake. Epilimnetic MeHg aq may be responding both to a decline in atmospheric Hg deposition as well as a decline in sulfate deposition, which is an important driver of mercury methylation in the environment. Results from this case study suggest that regional- to continental-scale decreases in both mercury and sulfate emissions have benefitted aquatic resources, even in the face of global increases in mercury emissions.

Minnesota↗
USGS2022

Trends of lesser prairie-chicken habitat extent and distribution on the Southern High Plains

The lesser prairie-chicken ( Tympanuchus pallidicinctus ) is a species of prairie grouse that occupies grassland ecosystems in the Southern and Central High Plains of the Great Plains. Reduced abundance and occupied ranges have led to increased conservation efforts throughout the species’ range. Habitat loss is considered the predominant cause of these declines. In the Southern High Plains of Texas and New Mexico, lesser prairie-chicken habitat corresponds to the Sand Shinnery Oak Prairie Ecoregion, which is comprised of a mixture of sand shinnery oak ( Quercus havardii) -dominated grasslands, sand sagebrush ( Artemisia filifolia )-dominated grasslands, and mixed grasslands. In sand shinnery oak–grassland communities, conversion to row-crop agriculture, continuous unmanaged livestock grazing, restriction of natural fire, invasive plant species (e.g., mesquite ( Prosopis spp. )), extensive use of herbicides, energy development, and a variety of other factors have also negatively affected ecosystem extent and function. We integrated historical maps and remote sensing-derived information to measure trends in the extent and geographical distribution of sand shinnery oak prairies in eastern New Mexico and northwest Texas. Potential lesser prairie-chicken habitat was reduced by 56% from a potential of 43,258 km 2 to 18,908 km 2 in ~115 years (since pre-settlement). Our assessment indicated both mixed grasslands and sand shinnery oak-dominated grasslands were transformed from large parcels of existing vegetation communities to urban settlements, row crops, roads, and industrial land uses by the 1970s. Currently, potential habitat is highly fragmented and restricted to isolated locations in Texas and New Mexico, with an increasing dominance in mixed grasslands, especially in the southeastern portion of the lesser prairie-chicken range. Sand shinnery oak-dominated grasslands have been declining rapidly, from 69% of its potential extent in 1985, 65% in 1995, 54% in 2005, to 42% in 2015. Mixed grasslands drastically declined to 50% of its potential distribution by 1985. Since then, it has been stable until the 2005–2015 period when it declined to 45% of its potential extent. Based on the 2015 assessment, the current potential habitat for lesser prairie chicken is estimated at 18,908 km 2 (1,890,800 ha or 4.6 million acres), where 13,126 km 2 corresponds to mixed grasslands and 5782 km 2 corresponds to sand shinnery oak-dominated grasslands.

New Mexico, Texas↗
USGS2014

Mapping mountain pine beetle mortality through growth trend analysis of time-series landsat data

Disturbances are key processes in the carbon cycle of forests and other ecosystems. In recent decades, mountain pine beetle (MPB; Dendroctonus ponderosae) outbreaks have become more frequent and extensive in western North America. Remote sensing has the ability to fill the data gaps of long-term infestation monitoring, but the elimination of observational noise and attributing changes quantitatively are two main challenges in its effective application. Here, we present a forest growth trend analysis method that integrates Landsat temporal trajectories and decision tree techniques to derive annual forest disturbance maps over an 11-year period. The temporal trajectory component successfully captures the disturbance events as represented by spectral segments, whereas decision tree modeling efficiently recognizes and attributes events based upon the characteristics of the segments. Validated against a point set sampled across a gradient of MPB mortality, 86.74% to 94.00% overall accuracy was achieved with small variability in accuracy among years. In contrast, the overall accuracies of single-date classifications ranged from 37.20% to 75.20% and only become comparable with our approach when the training sample size was increased at least four-fold. This demonstrates that the advantages of this time series work flow exist in its small training sample size requirement. The easily understandable, interpretable and modifiable characteristics of our approach suggest that it could be applicable to other ecoregions.

Colorado↗
USGS2025

Endemic and invasive species: A history of distributional trends in the fish fauna of the lower New River drainage

Invasive species are often central to conservation efforts, particularly when concerns involve potential impacts on rare, endemic native species. The lower New River drainage of the eastern United States is a watershed that warrants conservation assessment, as the system is naturally depauperate of native fish species and it is nearly saturated with non-native fish species: there are 31 natives, including at least nine endemic taxa, and 63 non-natives. For endemic taxa, we examined temporal distribution shifts (range expansions or contractions) based on percent change in the occupied watershed area. We contrasted these findings with time series analyses on distribution trends of non-native minnows (Leuciscidae) and darters (Percidae) based on growth curve models of the cumulative sum of the total area of occupied 12-digit hydrologic unit codes. We documented range reductions for six of nine endemic taxa. We determined that 11 of 18 non-native minnows and 6 of 8 non-native darters were invasive based on range expansions and associated invasion curve models. The endemic taxa are of conservation concern given the limited distribution ranges and documented population declines. Although among-species comparisons of range shifts do not support causal inference, documentation of changes in distribution ranges of endemic and invasive species is critical to inform conservation efforts.

North Carolina, Tennessee, Virginia, West Virginia↗
USGS2021

Population density, distribution, and trends of landbirds in the National Park of American Samoa, Ta‘ū and Tutuila Units (2011–2018)

The National Park of American Samoa (NPSA) was surveyed for landbirds from June through July, 2018. Surveys were conducted using point-transect distance sampling methods to estimate bird densities. This information provides the second datum in the time-series of landbird monitoring for long-term trends in landbird distribution, density, and abundance within NPSA. The Ta‘ū Unit and Tutuila Unit, each on separate islands, were first surveyed in 2011 and we tested for changes in densities between each survey year.

American Samoa↗
USGS2019

Monitoring boreal avian populations: How can we estimate trends and trajectories from noisy data?

Substantial effort has been dedicated to developing reliable monitoring schemes for North American bird populations, but our ability to monitor bird populations in the boreal forest remains limited because of the sparsity of long-term data sets, particularly in northerly regions. Given the importance of the boreal forest for many migratory birds, we set out to (1) summarize the main challenges associated with monitoring avian populations, (2) describe the available statistical tools for population monitoring and their applications, and (3) identify future directions to overcome current challenges in monitoring bird populations in the boreal forest. Defining and delineating populations of interest and identifying the drivers that affect those populations present the greatest current challenges. This is because migratory birds may be affected by many population-limiting processes at different stages of their annual life cycles. These factors are often hierarchically structured and can influence populations at the local, regional, or continental scales. Some of the challenges associated with delineating populations and identifying population drivers can be addressed via the plethora of sampling and analytic methods available to examine population change over time. Choosing the proper analytic methods depends on the goals of the study and the nature of the data such as single or multiple populations, repeated occurrence or count-based surveys, or demographic rates. Recent advances in hierarchical and integrated population models make these analytic approaches some of the most promising avenues for the development of future methods. However, these tools require large data sets, and acquiring sufficient data on bird populations and potential explanatory variables is difficult in the boreal forest. If the current challenges to monitoring birds in the boreal forest are to be overcome, serious effort should be dedicated to integrating existing data and making them accessible. Enhancing survey effort through multispecies surveys will also play an important role. Implementing spatially balanced sampling plans with a rotating panel design could balance the trade-offs between spatial versus temporal replication at an affordable cost. Improving the accessibility of environmental covariates that are spatially and temporally explicit would also enable development of mechanistic population models that improve our understanding of migratory bird population dynamics. Finally, given that long-term monitoring programs can take many decades before delivering reliable population trends and that organizational priorities often change over time, we suggest that collaborative efforts will help ensure the long-term survival of new monitoring programs.

Avian Conservation and Ecology↗
USGS2026

Mortality in the Hawaiian Short-eared Owl (Pueo, Asio flammeus sandwichensis): Causes and spatial trends

Trends in wildlife mortality can be particularly challenging to identify in low-density species where mortalities are less likely to be detected or documented. The Pueo, or Hawaiian Short-eared Owl ( Asio flammeus sandwichensis ), is the only native raptor that breeds on all the main Hawaiian Islands. The Pueo is state-listed as endangered on the island of Oʻahu, but drivers of population dynamics are not well known, including causes of mortality. In this study, existing records from organizations across the Hawaiian Islands were compiled to evaluate the causes of mortality in Pueo. Here, 242 unique records spanning the years 1993 to 2024 from state, federal, and private organizations were evaluated for causes of Pueo death. Trauma due to collisions with vehicles, wind turbines, fences, and other human-made objects was the leading detected cause of death (62%) followed by emaciation (13%) and disease (6%), with 19% of deaths due to unknown causes. The islands of Hawaiʻi and Kauaʻi, both with relatively low human populations, had the highest total number of reported mortalities (n = 77, 32%). The highest number of recorded mortalities was in the month of July (16%), and mortalities were generally higher from June through August. Although our study has detection biases, our results are consistent with global studies suggesting that blunt force trauma from vehicles, wind turbines, and other infrastructure are potentially important sources of mortality in raptors. Similar to other studies, rodenticide effects and infectious disease were potentially underestimated as sources of mortality, because most birds did not undergo a full necropsy. Further, there may be confounding variables due to ad hoc data collection. Development of a state-wide system for reporting and recording wildlife mortality along with future studies that include necropsies may improve our ability to discern which sources of mortality may be mitigated.

Hawaii↗
USGS2011

Trends in marine debris in the U.S. Caribbean and the Gulf of Mexico, 1996-2003

Marine debris is a widespread and globally recognized problem. Sound information is necessary to understand the extent of the problem and to inform resource managers and policy makers about potential mitigation strategies. Although there are many short-term studies on marine debris, a longer-term perspective and the ability to compare among regions has heretofore been missing in the U.S. Caribbean and the Gulf of Mexico. We used data from a national beach monitoring program to evaluate and compare amounts, composition, and trends of indicator marine debris in the U.S. Caribbean (Puerto Rico and the U.S. Virgin Islands) and the Gulf of Mexico from 1996 to 2003. Indicator items provided a standardized set that all surveys collected; each was assigned a probable source: ocean-based, land-based, or general-source. Probable ocean-based debris was related to activities such as recreational boating/fishing, commercial fishing and activities on oil/gas platforms. Probable land-based debris was related to land-based recreation and sewer systems. General-source debris represented plastic items that can come from either ocean- or land-based sources; these items were plastic bags, strapping bands, and plastic bottles (excluding motor oil containers). Debris loads were similar between the U.S. Caribbean and the western Gulf of Mexico; however, debris composition on U.S. Caribbean beaches was dominated by land-based indicators while the western Gulf of Mexico was dominated by ocean-based indicators. Beaches along the eastern Gulf of Mexico had the lowest counts of debris; composition was dominated by land-based indicators, similar to that found for the U.S. Caribbean. Debris loads on beaches in the Gulf of Mexico are likely affected by Gulf circulation patterns, reducing loads in the eastern Gulf and increasing loads in the western Gulf. Over the seven years of monitoring, we found a large linear decrease in total indicator debris, as well as all source categories, for the U.S. Caribbean. Lower magnitude decreases were seen in indicator debris along the eastern Gulf of Mexico. In contrast, only land-based indicators declined in the western Gulf of Mexico; total, ocean-based and general-source indicators remained unchanged. Decreases in land-based indicators were not related to human population in the coastal regions; human population increased in all regions over the time of the study. Significant monthly patterns for indicator debris were found only in the Gulf of Mexico; counts were highest during May through September, with peaks occurring in July. Inclement weather conditions before the time of the survey also accounted for some of the variation in the western Gulf of Mexico; fewer items were found when there were heavy seas or cold fronts in the weeks prior to the survey, while tropical storms (including hurricanes) increased the amount of debris. With the development around the globe of long-term monitoring programs using standardized methodology, there is the potential to help management at individual sites, as well as generate larger-scale perspectives (from regional to global) to inform decision makers. Incorporating mechanisms producing debris into marine debris programs would be a fruitful area for future research.

Gulf of Mexico and U.S. Carribean↗
USGS2021

Historical effective population size of North American hoary bat (Lasiurus cinereus) and challenges to estimating trends in contemporary effective breeding population size from archived samples

Background Hoary bats ( Lasiurus cinereus ) are among the bat species most commonly killed by wind turbine strikes in the midwestern United States. The impact of this mortality on species census size is not understood, due in part to the difficulty of estimating population size for this highly migratory and elusive species. Genetic effective population size (Ne) could provide an index of changing census population size if other factors affecting Ne are stable. Methods We used the NeEstimator package to derive effective breeding population size (Nb) estimates for two temporally spaced cohorts: 93 hoary bats collected in 2009–2010 and an additional 93 collected in 2017–2018. We sequenced restriction-site associated polymorphisms and generated a de novo genome assembly to guide the removal of sex-linked and multi-copy loci, as well as identify physically linked markers. Results Analysis of the reference genome with psmc suggested at least a doubling of Ne in the last 100,000 years, likely exceeding Ne = 10,000 in the Holocene. Allele and genotype frequency analyses confirmed that the two cohorts were comparable, although some samples had unusually high or low observed heterozygosities. Additionally, the older cohort had lower mean coverage and greater variability in coverage, and batch effects of sampling locality were observed that were consistent with sample degradation. We therefore excluded samples with low coverage or outlier heterozygosity, as well as loci with sequence coverage far from the mode value, from the final data set. Prior to excluding these outliers, contemporary Nb estimates were significantly higher in the more recent cohort, but this finding was driven by high values for the 2018 sample year and low values for all other years. In the reduced data set, Nb did not differ significantly between cohorts. We found base substitutions to be strongly biased toward cytosine to thymine or the complement, and further partitioning loci by substitution type had a strong effect on Nb estimates. Minor allele frequency and base quality bias thresholds also had strong effects on Nb estimates. Instability of Nb with respect to common data filtering parameters and empirically identified factors prevented robust comparison of the two cohorts. Given that confidence intervals frequently included infinity as the stringency of data filtering increased, contemporary trends in Nb of North American hoary bats may not be tractable with the linkage disequilibrium method, at least using the protocol employed here.

PeerJ↗
USGS2007

Long-term and storm-related shoreline change trends in the Florida Gulf Islands National Seashore

Coastal erosion on Northern Gulf of Mexico barrier islands is an ongoing issue that was exacerbated by the storm seasons of 2004 and 2005 when several hurricanes made landfall in the Gulf of Mexico. Two units of the Gulf Islands National Seashore (GUIS), located on Santa Rosa Island, a barrier island off the Panhandle coast of Florida, were highly impacted during the hurricanes of 2004 (Ivan) and 2005 (Cindy, Dennis, Katrina and Rita). In addition to the loss of or damage to natural and cultural resources within the park, damage to park infrastructure, including park access roads and utilities, occurred in areas experiencing rapid shoreline retreat. The main park road was located as close as 50 m to the pre-storm (2001) shoreline and was still under repair from damage incurred during Hurricane Ivan when the 2005 hurricanes struck. A new General Management Plan is under development for the Gulf Islands National Seashore. This plan, like the existing General Management Plan, strives to incorporate natural barrier island processes, and will guide future efforts to provide access to units of Gulf Islands National Seashore on Santa Rosa Island. To assess changes in island geomorphology and provide data for park management, the National Park Service and the U.S. Geological Survey are currently analyzing shoreline change to better understand long-term (100+ years) shoreline change trends as well as short-term shoreline impact and recovery to severe storm events. Results show that over an ~140-year period from the late 1800s to May 2004, the average shoreline erosion rates in the Fort Pickens and Santa Rosa units of GUIS were -0.7m/yr and -0.1 m/yr, respectively. Areas of historic erosion, reaching a maximum rate of -1.3 m/yr, correspond to areas that experienced overwash and road damage during the 2004 hurricane season. The shoreline eroded as much as ~60 m during Hurricane Ivan, and as much as ~88 m over the course of the 2005 storm season. The shoreline erosion rates in the areas where the park road was heavily damaged were as high as -70.2 m/yr over the 2004-2005 time period. Additional post-storm monitoring of these sections of the island, to assess whether erosion rates stabilize, will help to parks to determine the best long-term management strategy for the park infrastructure.

Open-File Report↗
USGS1987

Trends in American kestrel counts from the North American Breeding Bird Survey

A 15-year summary of the BBS data suggests that continental numbers of American Kestrels have increased during 1966-1979. According to analyses of physiographic and state/province strata, some areas are largely responsible for the increase in the U.S. and southern Canada and that only in Illinois and Arkansas have kestrels declined. BBS data are too few in Florida to detect trends concerning F. s. paulus. Surveying on special Raptor Routes, on which volunteers looked specifically for raptors while retracing their BBS route, did not significantly increase the kestrel counts, but did improve detection rates.

Book chapter↗