Geology topics

Laura Bond

Publications and source records attributed to Laura Bond.

5 recordsLinked to original sources

USGS2014

Assessing the potential effects of fungicides on nontarget gut fungi (trichomycetes) and their associated larval black fly hosts

Fungicides are moderately hydrophobic and have been detected in water and sediment, particularly in agricultural watersheds, but typically are not included in routine water quality monitoring efforts. This is despite their widespread use and frequent application to combat fungal pathogens. Although the efficacy of these compounds on fungal pathogens is well documented, little is known about their effects on nontarget fungi. This pilot study, a field survey in southwestern Idaho from April to December 2010 on four streams with varying pesticide inputs (two agricultural and two reference sites), was conducted to assess nontarget impact of fungicides on gut fungi, or trichomycetes. Tissues of larval black flies (Diptera: Simuliidae), hosts of gut fungi, were analyzed for pesticide accumulation. Fungicides were detected in hosts from streams within agricultural watersheds but were not detected in hosts from reference streams. Gut fungi from agricultural sites exhibited decreased percent infestation, density and sporulation within the gut, and black fly tissues had elevated pesticide concentrations. Differences observed between the sites demonstrate a potential effect on this symbiotic system. Future research is needed to parse out the details of the complex biotic and abiotic relationships; however, these preliminary results indicate that impacts to nontarget organisms could have far-reaching consequences within aquatic ecosystems.

Journal of the American Water Resources Associatio↗

USGS2013

Estimating raptor nesting success: old and new approaches

Studies of nesting success can be valuable in assessing the status of raptor populations, but differing monitoring protocols can present unique challenges when comparing populations of different species across time or geographic areas. We used large datasets from long-term studies of 3 raptor species to compare estimates of apparent nest success (ANS, the ratio of successful to total number of nesting attempts), Mayfield nesting success, and the logistic-exposure model of nest survival. Golden eagles (Aquila chrysaetos), prairie falcons (Falco mexicanus), and American kestrels (F. sparverius) differ in their breeding biology and the methods often used to monitor their reproduction. Mayfield and logistic-exposure models generated similar estimates of nesting success with similar levels of precision. Apparent nest success overestimated nesting success and was particularly sensitive to inclusion of nesting attempts discovered late in the nesting season. Thus, the ANS estimator is inappropriate when exact point estimates are required, especially when most raptor pairs cannot be located before or soon after laying eggs. However, ANS may be sufficient to assess long-term trends of species in which nesting attempts are highly detectable.

Journal of Wildlife Management↗

USGS2011

Migration patterns, use of stopover areas, and austral summer movements of Swainson's hawks

From 1995 to 1998, we tracked movements of adult Swainson's Hawks ( Buteo swainsoni ), using satellite telemetry to characterize migration, important stopover areas, and movements in the austral summer. We tagged 46 hawks from July to September on their nesting grounds in seven U.S. states and two Canadian provinces. Swainson's Hawks followed three basic routes south on a broad front, converged along the east coast of central Mexico, and followed a concentrated corridor to a communal area in central Argentina for the austral summer. North of 20° N, southward and northward tracks differed little for individuals from east of the continental divide but differed greatly (up to 1700 km) for individuals from west of the continental divide. Hawks left the breeding grounds mid-August to mid-October; departure dates did not differ by location, year, or sex. Southbound migration lasted 42 to 98 days, northbound migration 51 to 82 days. Southbound, 36% of the Swainson's Hawks departed the nesting grounds nearly 3 weeks earlier than the other radio-marked hawks and made stopovers 9.0–26.0 days long in seven separate areas, mainly in the southern Great Plains, southern Arizona and New Mexico, and north-central Mexico. The birds stayed in their nonbreeding range for 76 to 128 days. All used a core area in central Argentina within 23% of the 738 800-km 2 austral summer range, where they frequently moved long distances (up to 1600 km). Conservation of Swainson's Hawks must be an international effort that considers habitats used during nesting and non-nesting seasons, including migration stopovers.

The Condor↗

USGS2006

A landscape-scale model of yellow-billed loon (Gavia adamsii) habitat preferences in northern alaska

We modeled yellow-billed loon ( Gavia adamsii ) habitat preferences in a 23,500 km 2 area of northern Alaska using intensive aerial surveys and landscape-scale habitat descriptors. Of the 757 lakes censused, yellow-billed loons occupied 15% and Pacific loons ( G. pacifica ) 42%. Lake area, depth, proportion of shoreline in aquatic vegetation, shoreline complexity, hydrological connectivity (stream present within 100 m or absent), and an area–connectivity interaction were positive, significant predictors of yellow-billed loon presence in a multivariate logistic regression model, but distance to nearest river or Beaufort Sea coast were not. Predicted yellow-billed loon presence was 13 and 4.7 times more likely on deep and medium lakes, respectively, than on shallow lakes that freeze to the bottom. On small lakes (<60 ha), predicted yellow-billed loon presence was 4.8–1.7 times more likely on lakes with hydrological connectivity than without, but connectivity was not important at most lake sizes (65–750 ha). Yellow-billed loon broods depend on fish available in the brood-rearing lake, and we suggest that a dependable supply of fish is more likely in larger lakes, those deep enough to have open water under winter ice, and those near streams. Highly convoluted shorelines and those with aquatic vegetation provide loon nesting and brood-rearing sites, as well as fish habitat. Pacific loon absence was a significant, positive predictor when added to the habitat model, indicating that yellow-billed loons were four times more likely on lakes without Pacific loons.

Hydrobiologia↗

USGS2002

Trends in midwinter counts of bald eagles in the contiguous United States, 1986-2000

We estimated statewide, regional, and national trends in counts of Bald Eagles ( Haliaeetus leucocephalus ) along selected routes in the contiguous United States during midwinter, 1986-2000. Each January, several hundred observers collected data as part of a survey initiated by the National Wildlife Federation in 1979. To analyze these data, we used only those routes surveyed consistently in at least four years and on which at least four eagles were counted in a single year. We included surveys conducted during fog or precipitaion after determining that changes in weather conditions probably did not affect trend estimates. Our final analysis, using a hierarchical mixed model, was based on 101,777 eagle sightings during 5,180 surveys of 563 routes in 42 states. In the model, fixed effects were year, region, and route-length category; the random effect was the route itself. Model-based estimates of Bald Eagle counts throughout the U.S. increased 1.9% yr -1 , but trend estimates varied by region. Estimated trends were statistically significant, and positive, in the northeastern U.S. (6.1% yr -1 ), but were not significant in other regions. The proportion of increasing counts was higher north of 40° N and east of 100° W. Trends in numbers of adults and immatures showed similar geographic patterns, but counts of adults increased at a higher rate. Overall, trends were more similar to those identified by the Christmas Bird Count than the Breeding Bird Survey. In spite of limitations, the survey is a cost-effective way to monitor wintering eagles in the lower 48 states. We discuss estimated trends in the context of increased urbanization, changed weather, and recovery from pesticide pollution.

Bird Populations↗