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At least 1,315 records · Page 73Linked to original sources
USGS2006

Genetic variation among subspecies of Least Tern (Sterna antillarum): Implications for conservation

DNA sequence variation from two nuclear introns and part of the mitochondrial cytochrome-b gene were used to Evaluate population structure among three subspecies of Least Term that nest in the United States (California [Sterna antillarum browni], Interior [S. a. athalassos], Eastern [S. a. antillarum]). Sequence variation was highest for nuclear intron XI (Gadp) within the glyceraldehyde-3-phosphate dehydrogenase gene. The second nuclear intron was fixed for the same allele in all subspecies. Fixation indices, FST and MST, for Gadp indicated genetic divergence between California and Interior subspecies. Estimates of nuclear gene flow were <4 individuals/generation, except between the Interior and Eastern subspecies (4 individuals/generation). Genetic indices for mitochondrial DNA did not differ among subspecies, and gene flows (reflecting female dispersal) ranged from 10 to 83 individuals/generation. Reservations are expressed about the validity of the current subspecific divisions and further research is required, including their taxonomic relationship to the Little Tern (Sterna albifrons).

Waterbirds↗
USGS2002

Conservation status of the buff-breasted sandpiper: Historic and contemporary distribution and abundance in south America

We present historic and contemporary information on the distribution and abundance of Buff-breasted Sandpipers ( Tryngites subruficollis ) in South America. Historic information was collated from the literature, area ornithologists, and museums, whereas contemporary data were derived from surveys conducted throughout the main wintering range in Argentina, Uruguay, and Brazil during the austral summers of 1999 and 2001. Variable circular plot sampling was used to estimate population densities. During 1999, the highest concentration of Buff-breasted Sandpipers in Argentina was in southern Bahía Samborombón (General Lavalle District) and areas north of Mar Chiquita coastal lagoon. During 2001, the highest concentrations in Brazil were at Ilha da Torotama and Lagoa do Peixe National Park. During 1999 and 2001, the highest concentrations of Buff-breasted Sandpipers in Uruguay were found along three lagoons (Laguna de Rocha, Laguna de Castillos, and Laguna Garzón) bordering the Atlantic Ocean. Population densities (birds/ha) of Buff-breasted Sandpipers were 0.11 (95% C.I. = 0.04–0.31) in Argentina, 1.62 (0.67–3.93) in Brazil, and 1.08 (0.37–3.18) in Uruguay. High turnover rates at survey sites, due to the formation of large, mobile flocks, contributed to moderately large confidence intervals around our population density estimates. Nevertheless, compared with historic accounts of Buff-breasted Sandpipers, our survey data indicate the population size of this species has declined substantially since the late 1800s and contemporary information suggests the species has continued to decline during the past three decades. Buff-breasted Sandpipers were found almost exclusively in pasturelands and appear to depend heavily upon intensive grazing by livestock, which maintain suitable short grass conditions. We discuss the need for protection of critical areas and proper range management to ensure appropriate habitat remains available for the species, and provide suggestions for future research needs.

The Wilson Bulletin↗
USGS2003

Ecohydrology of a resource-conserving semiarid woodland: Effects of scale and disturbance

In semiarid landscapes, the linkage between runoff and vegetation is a particularly close one. In this paper we report on the results of a long-term and multiple-scale study of interactions between runoff, erosion, and vegetation in a pi ñ on–juniper woodland in New Mexico. We use our results to address three knowledge gaps: (1) the temporal scaling relationships between precipitation and runoff; (2) the effects of spatial scale on runoff and erosion, as influenced by vegetation; and (3) the influence of disturbance on these relationships. On the basis of our results, we tested three assumptions that represent current thinking in these areas (as evidenced, for example, by explicit or implicit assumptions embedded in commonly used models). The first assumption, that aggregated precipitation can be used as a surrogate for total runoff in semiarid environments, was not verified by our findings. We found that when runoff is generated mainly by overland flow in these systems, aggregated precipitation amounts alone (by year, season, or individual event) are a poor predictor of runoff amounts. The second assumption, that at the hillslope and smaller scales runoff and erosion are independent of spatial scale, was likewise not verified. We found that the redistribution of water and sediment within the hillslope was substantial and that there was a strong and nonlinear reduction in unit-area runoff and erosion with increasing scale (our scales were slope lengths ranging from 1 m to 105 m). The third assumption, that disturbance-related increases in runoff and erosion remain constant with time, was partially verified. We found that for low-slope-gradient sites, disturbance led to accelerated runoff and erosion, and these conditions may persist for a decade or longer. On the basis of our findings, we further suggest that (a) disturbance alters the effects of scale on runoff and erosion in a predictable way—scale relationships in degraded areas will be fundamentally different from those in nondegraded areas because more runoff will escape off site and erosion rates will be much higher; and (b) there exists a slope threshold, below which semiarid landscapes will eventually recover following disturbance and above which there will be no recovery without mitigation or remediation.

Ecological Monographs↗
USGS2016

Creating a Coastal National Elevation Database (CoNED) for science and conservation applications

The U.S. Geological Survey is creating the Coastal National Elevation Database, an expanding set of topobathymetric elevation models that extend seamlessly across coastal regions of high societal or ecological significance in the United States that are undergoing rapid change or are threatened by inundation hazards. Topobathymetric elevation models are raster datasets useful for inundation prediction and other earth science applications, such as the development of sediment-transport and storm surge models. These topobathymetric elevation models are being constructed by the broad regional assimilation of numerous topographic and bathymetric datasets, and are intended to fulfill the pressing needs of decision makers establishing policies for hazard mitigation and emergency preparedness, coastal managers tasked with coastal planning compatible with predictions of inundation due to sea-level rise, and scientists investigating processes of coastal geomorphic change. A key priority of this coastal elevation mapping effort is to foster collaborative lidar acquisitions that meet the standards of the USGS National Geospatial Program's 3D Elevation Program, a nationwide initiative to systematically collect high-quality elevation data. The focus regions are located in highly dynamic environments, for example in areas subject to shoreline change, rapid wetland loss, hurricane impacts such as overwash and wave scouring, and/or human-induced changes to coastal topography.

Journal of Coastal Research↗
USGS2021

Case 3853 – Eumeces niger Hombron & Jacquinot, 1853 (currently Emoia nigra) (Reptilia, Scincidae): proposed conservation of prevailing usage by setting aside a lectotype designation for Gongylus (Eumeces) freycineti Duméril & Bibron, 1839 (currently Emoia atrocostata freycineti)

The purpose of the present application, under Articles 74.1.1 and 81.1 of the Code, is to maintain consistent usage of the commonly used name Emoia nigra (Hombron & Jacquinot, 1853 ) by setting aside a lectotype designation for Gongylus ( Eumeces ) freycineti Duméril & Bibron, 1839 by Wells & Wellington in 1985 in favour of a later lectotype designation by Brown in 1991 .

The Bulletin of Zoological Nomenclature↗
USGS1997

The disappearance of Guam's wildlife: New insights for herpetology, evolutionary ecology, and conservation

The wealth of data generated from intensive study of the brown tree snake as a result of the need to control introduced populations of this pest species allow several important conclusions. First, that the snakes on Guam are extraordinary in terms of their absolute abundance and in terms of their ability to exploit a broad prey base. Our data suggest an exceptionally high reproductive success on Guam for a snake with an otherwise unnoteworthy reproductive capability and life history (i.e. small clutch size, typical ontogenetic shift from small heterothermic prey to larger homeotherms). Especially important was the snakes versatility in taking advantage of extremely common prey on islands; population expansion was slow but survival was maximal, ultimately leading to high population levels. The brown tree snake shares many attributes with other snakes that could cause similar biodiversity crises in a wide variety of contexts in which they lack coevolutionary histories (especially formerly snake-free island environments). As opposed to their relatively poor history as over-water dispersers, snakes may be especially problematic as travelers in increasing ship and air traffic between widely separated geographic regions of the world.

BioScience↗
USGS1987

Ecology, behavior, and conservation of the Maui parrotbill

The distribution, habitat response, sexual dimorphism, foraging, breeding, and flocking behavior of Maui Parrotbills (Pseudonestor xanthophrys ) were studied over a five year period. The species' present range is confined to montane rainforest on eastern Maui, but dry lowland habitats on Maui and Molokai were occupied before Polynesian contact. Birds occurred from 1,250 to 2,150 m elevation, becoming most abundant at 1,750 to 2,000 m. In Kipahulu Valley, birds moved to lower elevations in some seasons. Birds tended to forage in the subcanopy and understory, with 66% of the prey captured 1 to 5 m above ground. Plant species use deviated from expectations based on availability. The most frequent means of prey capture was excavation for timber-boring insects in dead branches on live plants. Foraging accounted for 39% of the diurnal time budget; an average prey item appeared to account for 1% of the daily energy intake. The principal limiting factors appeared to be habitat loss, avian disease, habitat degradation, predation, and competition from exotic species. Control of pig populations is a needed management action.

Condor↗
USGS1936

Stream flow, suspended, and dissolved matter in streams on and near soil conservation project, La Crosse, WI

Measurements of stream flow and movement of suspended natter have been obtained at stations on the La Crosse project as indicated below: Little La Crosse River near Leon, Wis. Drainage area 77.1 square miles. The station is in sec. 3, T. 16 N., R. 4 W., 2 miles northwest of Leon, Monroe County; established March 14, 1934; suspended matter determined from April 1, 1934. Coon Creek at Coon Valley, Wis. Drainage area 77.2 square miles. The station is in sec. 7, T. 14 N., R. 5 W., in the village of Coon Valley, Vernon County; established March 16, 1934; suspended matter determined from April 6, 1934. Coon Creek near Stoddard, Wis. Drainage area 115 square miles. The station is in sec. 25, T. 14 N., R. 7 W., 3 1/4 miles east of Stoddard, Vernon County; established March 28, 1934; suspended matter determined from April 6, 1934.

Wisconsin↗