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At least 703 records · Page 39Linked to original sources
USGS2004

Susceptibility of the leaf-eating beetle, Galerucella calmariensis, a biological control agent for purple loosestrife (Lythrum salcaria), to three mosquito control larvicides

We evaluated the susceptibility of Galerucella calmariensis, a species used to control purple loosestrife (Lythrum salicaria), to three mosquito control larvicides. Larvae and adults were fed loosestrife cuttings dipped in Abate? (<375 g?L-1), Altosid? (<250 g?L-1), and Bacillus thuringiensis var israeliensis (Bti) (<110 g?L-1). Eggs on cuttings were dipped in the same concentrations. Pupae were immersed in Abate and Altosid solutions (<474.4 ug?L-1 and <1,169.2 ug?L-1, respectively). Hatching success of eggs dipped in Abate (>3.75 g?L-1) was reduced significantly and survival was significantly lower among larvae and adults eating cuttings dipped in Abate (>0.17 g?L-1 and >2.27 g?L-1, respectively). Hatching success of eggs dipped in Altosid (>2.52 g?L-1) was reduced significantly. With exposure to Altosid, larval survival to pupation and adult emergence was reduced significantly at concentrations of >2.92 g?L-1 and >0.63 g?L-1, respectively. Altosid (>0.23 g?L-1) also delayed the onset of pupation and adult emergence among larvae that survived to pupate. Larvae that survived with exposure to Altosid (>1.72 g?L-1) grew to 70% larger than those exposed to lower concentrations. Pupal survival was unaffected with exposure to Abate and Altosid and adult survival was unaffected with exposure to Altosid. Bacillus thuringiensis var israeliensis did not adversely affect any life stage of G. calmariensis. The mean Abate concentration on cuttings exposed to operational spraying was in the range that reduced egg hatchability and adult survival but was higher than concentrations that caused complete mortality of larvae. The mean Altosid concentration on cuttings exposed to operational spraying was in the range that reduced hatching success in eggs and delayed pupation and adult emergence of larvae.

Environmental Toxicology and Chemistry↗
USGS2010

Biologic origin of iron nodules in a marine terrace chronosequence, Santa Cruz, California

The distribution, chemistry, and morphology of Fe nodules were studied in a marine terrace soil chronosequence northwest of Santa Cruz, California. The Fe nodules are found at depths <1 m on all terraces. The nodules consisted of soil mineral grains cemented by Fe oxides. The nodules varied in size from 0.5 to 25 mm in diameter. Nodules did not occur in the underlying regolith. The Fe-oxide mineralogy of the nodules was typically goethite; however, a subset of nodules consisted of maghemite. There was a slight transformation to hematite with time. The abundance of soil Fe nodules increased with terrace age on the five terraces studied (aged 65,000-226,000 yr). Scanning electron microscopy (SEM) revealed Fe-oxide-containing fungal hyphae throughout the nodules, including organic structures incorporating fine-grained Fe oxides. The fine-grained nature of the Fe oxides was substantiated by M??ssbauer spectroscopy. Our microscopic observations led to the hypothesis that the nodules in the Santa Cruz terrace soils are precipitated by fungi, perhaps as a strategy to sequester primary mineral grains for nutrient extraction. The fungal structures are fixed by the seasonal wetting and dry cycles and rounded through bioturbation. The organic structures are compacted by the degradation of fungal C with time. ?? Soil Science Society of America. All rights reserved.

Soil Science Society of America Journal↗
USGS1967

Radar remote sensing in biology

The present status of research on discrimination of natural and cultivated vegetation using radar imaging systems is sketched. The value of multiple polarization radar in improved discrimination of vegetation types over monoscopic radars is also documented. Possible future use of multi-frequency, multi-polarization radar systems for all weather agricultural survey is noted.

BioScience↗
USGS1986

Nest-site biology of the California condor

A study of 72 historical and recent nests of the California Condor (Gymnogyps californianus) has revealed considerable variability in nest-site characteristics. This paper primarily summarizes the data on nest elevations and dimensions, entrance orientations, nest longevity and re-use, vulnerability of sites to natural enemies, and use of sites by other species. Although all known nests have been natural cavities, some have been little more than overhung ledges on cliffs, while others have been deep, dark caves with nest chambers completely concealed from the outside. Two sites have been cavities in giant sequoias (Sequoiadendron giganteum). Contrary to previous assumptions, condors do modify the characteristics of their nest sites significantly and commonly construct substrates of coarse gravel on which to rest their eggs. Many nests have been completely accessible to terrestrial predators, many have been poorly protected from avian predators, and some have had structural flaws leading directly to nesting failure. The use of suboptimal sites has not been clearly related to a scarcity of better quality sites.

Condor↗
USGS1984

Breeding biology of Pacific white-fronted geese

Nesting ecology of Pacific white-fronted geese ( Anser albifrons frontalis ) was studied on a 9.9-km 2 area on the Yukon-Kuskokwim (Y-K) Delta, Alaska, during 1977-79. Availability of nesting habitat varied considerably among years because of differences in time of snow- and icemelt. Mean clutch size was 3.7 eggs in the late spring thaw year and 5.2 and 5.7 eggs in early snowmelt years. Peak (and duration) of nest initiation was 1-2 June (16 days) in the late spring and 15-18 May (20-21 days) during early springs. When nest sites were available early, the time interval between arrival and date of nest initiation closely approximated the time required for rapid yolk development. This suggests that whitefronts may be physiologically prevented from nesting earlier in such years. The duration of nest initiation was comparable to that of other goose species nesting on the Y-K Delta, but longer than for goose populations of several species nesting farther north or in the midcontinent. Overall, 68% of whitefront nests were in lowland habitat, 23% in intermediate habitat, and 10% in upland habitat, but habitat use varied significantly between early and late years. Whitefronts most commonly nested on slough banks (55%), lake shores (23%), and grass-sedge meadows (11%). A quantitative description of vegetation associated with nest sites is given. Major causes of nest destruction were flooding (28%) and predation (9%). Nesting success over the 3-year period averaged 62%.

Alaska↗
USGS1995

Biological consequences of relocating grizzly bears in the Yellowstone ecosystem

Relocating grizzly bears ( Ursus arctos ) from human/bear conflict situations has been a standard management procedure. Using data from Yellowstone National Park, we present components of situations that may affect the outcome of a relocation. Survival rates of transported bears were lower ( l x = 0.83) ( P = 0.001) than those not transported ( l x = 0.89). Survival was largely affected by whether the bear returned to the capture site ( P = 0.029). Return rate was most affected by distance transported ( P = 0.012) and age-sex group ( P = 0.014). Return rates decreased at distances -75 km, and subadult females returned least ( P = 0.050) often. Because of low survival and high return rates, transporting grizzly bears should be considered a final action to eliminate a conflict situation. However, transporting females must be considered a viable management technique because transports of some individuals have resulted in contributions to the population through successful reproduction.

Journal of Wildlife Management↗
USGS1990

Stability and bias of classification rates in biological applications of discriminant analysis

We assessed the sampling stability of classification rates in discriminant analysis by using a factorial design with factors for multivariate dimensionality, dispersion structure, configuration of group means, and sample size. A total of 32,400 discriminant analyses were conducted, based on data from simulated populations with appropriate underlying statistical distributions. Simulation results indicated strong bias in correct classification rates when group sample sizes were small and when overlap among groups was high. We also found that stability of the correct classification rates was influenced by these factors, indicating that the number of samples required for a given level of precision increases with the amount of overlap among groups. In a review of 60 published studies, we found that 57% of the articles presented results on classification rates, though few of them mentioned potential biases in their results. Wildlife researchers should choose the total number of samples per group to be at least 2 times the number of variables to be measured when overlap among groups is low. Substantially more samples are required as the overlap among groups increases

Journal of Wildlife Management↗
USGS1980

Biological considerations in the delineation of critical habitat

Grizzly bears ( Ursus arctos ) require large areas to satisfy their needs for food, cover, and space. They thrive best where disturbance by man is minimal. It is not a coincidence that the two major grizzly bear populations in the lower 48 states exist in large wilderness systems closely associated with two large national parks and a relatively large game preserve. If management objectives for these areas do not change, and man-bear interactions can be kept low, viable grizzly bear populations can be maintained. Outside of parks and wilderness areas, the picture is less clear. Grizzly bears adapt to some habitat modifications. the extent of their adaptability to habitat modification or human interaction is largely unknown. Answers to many pertinent questions will be slow in coming. In the meantime, management policies based on common sense rather than on adversary reactions among agencies are the best insurance of the grizzlies' survival.

Book chapter↗
USGS2007

Biology and impacts of Pacific island invasive species. 2. Boiga irregularis , the Brown Tree Snake (Reptilia: Colubridae)

The Brown Tree Snake, Boiga irregularis (Merrem, 1802), was accidentally transported to the island of Guam shortly after World War II. Over the following two decades it spread throughout the island with little public or professional recognition of its extent or impacts. This secretive nocturnal arboreal snake occurs in all habitats on Guam, from grasslands to forests. Under the right conditions, it is capable of high rates of reproduction and population growth. The Brown Tree Snake caused the extirpation of 13 of Guam's 22 native breeding birds and contributed to the extirpation of several species of native bats and lizards. Guam's 12 forest birds were especially impacted, with 10 species eliminated and the other two severely reduced. In addition, the snake continues to substantially impact domestic poultry, pets, the island's electrical power infrastructure, and human health. To protect other vulnerable Pacific islands, the U.S. government annually spends several million dollars inspecting cargo outbound from Guam to exclude Brown Tree Snakes. Cargo destinations most at risk are in Micronesia, especially the Northern Mariana Islands, but Guam also has direct air transportation links to Hawai'i that will soon be supplemented with direct ship traffic. Ultimately, all Pacific islands are at risk but especially those obtaining cargo through Guam. ?? 2007 by University of Hawai'i Press. All rights reserved.

Pacific Science↗
USGS2013

Biology and impacts of Pacific island invasive species 9. Capra hircus , the feral goat, (Mammalia: Bovidae)

Domestic goats, Capra hircus , were intentionally introduced to numerous oceanic islands beginning in the sixteenth century. The remarkable ability of C. hircus to survive in a variety of conditions has enabled this animal to become feral and impact native ecosystems on islands throughout the world. Direct ecological impacts include consumption and trampling of native plants, leading to plant community modification and transformation of ecosystem structure. While the negative impacts of feral goats are well-known and effective management strategies have been developed to control this invasive species, large populations persist on many islands. This review summarizes the impacts of feral goats on Pacific island ecosystems, and the management strategies available to control this invasive species.

Pacific Science↗