| quantification of low levels of organochlorine pesticides using small volumes (<or=100 microl) of plasma of wild birds through gas chromatography negative chemical ionization mass spectrometry. | a solid phase extraction and gas chromatography with negative chemical ionization mass spectrometry in scan mode (gc-nci-ms) method was developed to identify and quantify for the first time low levels of organochlorine pesticides (ocs) in plasma samples of less than 100 microl from wild birds. the method detection limits ranged from 0.012 to 0.102 pg/microl and the method reporting limit from 0.036 to 0.307 pg/microl for alpha, gamma, beta and delta-hexachlorocyclohexane (hch), heptachlor, aldri ... | 2007 | 17240024 |
| the use of digital photos to assess visual cover for wildlife in rangelands. | grassland vegetation can provide visual cover for terrestrial vertebrates. the most commonly used method to assess visual cover is the robel pole. we test the use of digital photography as a more accurate and repeatable method. we assessed the digital photography method on four forage grassland species (pseudoroegneria spicata, festuca campestris, poa pratensis, achnatherum richardsonii). digital photos of 2-dimensional cutout silhouettes of three bird species sharp-tailed grouse, western meadow ... | 2010 | 20226585 |
| blood-feeding patterns of the culex pipiens complex in sacramento and yolo counties, california. | mosquitoes in the culex pipiens complex are competent vectors of west nile virus (wnv; family flaviviridae, genus flavivirus) in the laboratory, and field-collected mosquitoes have tested positive for the virus in california and elsewhere. a better understanding of cx. pipiens complex blood-feeding patterns will help define the threat that these mosquitoes pose to human health and their role in wnv amplification in northern california. we collected blood-engorged cx. pipiens complex mosquitoes f ... | 2011 | 21485380 |
| impacts of a severe drought on grassland birds in western north dakota. | we studied the effect of a severe drought on the population dynamics and community structure of grassland birds in western north dakota. during the spring and summer of 1988 the northern great plains suffered one of the warmest, driest periods in its recorded history. we compared the changes in bird populations and nesting productivity over a 3-yr period before, during, and after the drought. total grassland bird density declined 61% (p < .05) between june 1987 and june 1988. densities of six of ... | 1992 | 27759255 |
| livestock grazing supports native plants and songbirds in a california annual grassland. | over eight years we measured the effects of plant community composition, vegetation structure, and livestock grazing on occurrence of three grassland bird species-western meadowlark (sturnella neglecta), horned lark (eremophila alpestris), and grasshopper sparrow (ammodramus savannarum)-at sites in central california during breeding season. in california's mediterranean-type climatic region, coastal and inland grassland vegetation is dominated by exotic annual grasses with occasional patches of ... | 2017 | 28614358 |
| effects of the conservation reserve program on northern bobwhite and grassland birds. | the conservation reserve program (crp) has converted just over 36 million acres of cropland into potential wildlife habitat, primarily grassland. thus, the crp should benefit grassland songbirds, a group of species that is declining across the united states and is of conservation concern. additionally, the crp is an important part of multi-agency, regional efforts to restore northern bobwhite populations. however, comprehensive assessments of the wildlife benefits of crp at regional scales are l ... | 2008 | 18175201 |
| temporal variation in habitat structure and shrubsteppe bird dynamics. | we investigate the role of temporal variation in habitat physiognomy in influencing the dynamics of shrubsteppe bird populations and communities. during a 3-y (1977-1979) study of 14 sites in the northern great basin of north america, annual precipitation varied substantially, with one of the driest years on record followed by one of the wettest. this resulted in significant physiognomic variation (increasing height and coverage of vegetation, decreasing horizontal patchiness), mediated largely ... | 1980 | 28309621 |
| pathogenicity of microtetrameres centuri barus, 1966 (nematoda: tetrameridae) in meadowlark. | pathogenicity of adult and third-stage microtetrameres centuri barus, 1966 in meadowlarks (sturnella spp.) is reported for the first time. adults do not encyst; their effects are mainly mechanical. some glandular atrophy of its avian host is detected but no marked inflammatory response is exhibited. juveniles also encyst experimentally in the perivisceral sinus of the grasshopper (alternate host) hemocoel. | 1970 | 19322271 |
| ectoparasites of eastern and western meadowlarks from the rio grande plains of south texas. | | 1988 | 3357173 |
| the numbers of insects destroyed by western meddowlarks (sturnella neglecta). | | 1912 | 17792454 |
| direct and indirect effects of a keystone engineer on a shrubland-prairie food web. | keystone engineers are critical drivers of biodiversity throughout ecosystems worldwide. within the north american great plains, the black-tailed prairie dog is an imperiled ecosystem engineer and keystone species with well-documented impacts on the flora and fauna of rangeland systems. however, because this species affects ecosystem structure and function in myriad ways (i.e., as a consumer, a prey resource, and a disturbance vector), it is unclear which effects are most impactful for any given ... | 2020 | 33006165 |
| songbird response to rest-rotation and season-long cattle grazing in a grassland sagebrush ecosystem. | grazing on natural rangelands, which are areas dominated by native vegetation that are used for livestock grazing, can achieve desired vegetation outcomes, preserve native habitat, and economically benefit multiple stakeholders. it is a powerful tool that can be manipulated to reduce wildlife declines and benefit ecosystems. however, the benefits of conservation grazing systems on many wildlife communities remain relatively unexplored. we compared songbird communities between two grazing systems ... | 2017 | 28946000 |
| how do small birds evolve in response to climate change? data from the long-term record at la brea tar pits. | biology textbooks describe the small changes in the beaks of the galápagos finches as exemplars of how birds evolve in response to environmental changes. however, recent studies of the abundant fossil birds at rancho la brea find no evidence of evolutionary responses to the dramatic climate changes of the glacial-interglacial cycle over the past 35 000 years: none of the large birds exhibit any change in body size or limb proportions, even during the last glacial maximum approximately 18 000-20 ... | 2020 | 31912657 |
| noisy anthropogenic infrastructure interferes with alarm responses in savannah sparrows (passerculus sandwichensis). | many birds rely on anti-predator communication to protect their nests; however, anthropogenic noise from industrial activities such as oil and gas development may disrupt acoustic communication. here, we conducted acoustic playback experiments to determine whether savannah sparrows (passerculus sandwichensis) responded to conspecific alarm calls by delaying feeding visits, and whether this response was impaired by noise-producing natural gas compressor stations, generator- or grid-powered screw ... | 2018 | 29892404 |