Operant conditioning and copulation solicitation display assays reveal a stable preference for local song by female swamp sparrows <Emphasis Type="Italic">Melospiza georgiana</Emphasis>

Operant conditioning assays are increasingly being used to test mating signal preferences in female birds. Operant behavior may be seen as farther removed from mate choice behavior as compared to other methods for measuring mating signal preferences, which could limit the evolutionary interpretation of operant results. I compared the song preferences of female swamp sparrows (Melospiza georgiana) as measured both by a copulation solicitation display assay and by an operant preference test. Both methods revealed a strong preference for songs from the females' Conneaut Marsh breeding population over songs from a Millbrook population over 500 km distant, which remained stable after extensive exposure to Millbrook songs. Further, there was a striking congruence in results on an individual level from the two assays. These findings support the conclusion that operant methods reveal evolutionarily significant mate choice preferences, providing the opportunity to study such preferences under circumstances when the copulation solicitation assay is less practical.     

Resources from another place and time: responses to pulses in a spatially subsidized system

As the theoretical bases for the dynamics of spatially subsidized communities emerge, ecologists question whether spatially subsidized communities exhibit similar structure or dynamics to communities that receive strongly pulsed resources. In both cases, communities may be structured by responses to resources that are potentially absent at any given point in time (pulsed communities) or space (subsidized communities), even if pulsed resources are part of the in situ productivity of the system or the subsidies arrive as a relatively constant input from a nearby system. The potential for significant spatial or temporal resource limitation, therefore, may be a key factor influencing in similar ways the persistence of populations, the structure and dynamics of communities, and the evolution of specific life history traits. In most complex systems, however, multiple resources may arrive for various trophic entities at various points in time and from various points in space, and thus it may be difficult to separate or compare the dynamics of spatially subsidized and pulsed systems. In this paper, we explore the effects of interactions between pulses and subsidies in plant and animal populations and communities on highly pulsed and variably subsidized islands in the Gulf of California. While many of the plant and animal communities on the unsubsidized islands in this system respond to pulses of rain in classic ways, responses to these rain pulses on islands subsidized by seabird guano or other marine resources are quite different and variable, and depend on a combination of life history characteristics, physiology, competitive interactions, and trophic relationships. These variable responses to rain pulses then translate into large differences in dynamics and community structure of subsidized vs. unsubsidized islands. Indeed, most systems experience both temporal pulses and spatial subsidies. When considered in tandem, complementary or synergistic effects of the multiple, temporally and spatially variable resources may emerge that help explain complex food web structure and dynamics.     

Is bird song a reliable signal of aggressive intent? A reply

We advocate assessing the reliability of signals of aggressive intent by eliciting aggressive signaling from a subject, giving the subject an opportunity to attack a model, and testing whether the subject’s displays predict a subsequent attack. Using this design, we found that most singing behaviors are poor predictors of attack in song sparrows (Melospiza melodia). Laidre and Vehrencamp (Behav Ecol Sociobiol, DOI 10.1007/s00265-007-0539-3, 2008) suggested altering our experimental design to make the model more realistic; it remains to be seen whether such design changes would change the association between display and attack. Laidre and Vehrencamp (Behav Ecol Sociobiol, DOI 10.1007/s00265-007-0539-3, 2008) also suggested that the reliability of soft song, the one display that predicts attack in song sparrows, can be explained by a vulnerability cost. We question the rationale for a vulnerability cost for this display and suggest instead that soft song has a competing functions cost, in that, by using soft song to counter an intruder, a male sacrifices other possible functions of vocal signaling.     

Distribution and toxicity of monosodium methanearsonate following oral administration of the herbicide to dairy sheep and goats

Iranian fat-tailed sheep and dairy goats were administered the herbicide monosodium methanearsonate orally at a dose of 10 mg. MSMA (as arsenic) per kg. of body weight. The concentration time curves of MSMA in the blood of sheep and goats followed a first order composite exponential equation of the form: Cb(t) = Ae- alpha t + Be- beta t - C degrees be-kat. Absorption, distribution and elimination of MSMA, therefore, corresponds to an open two-compartment model. Arsenic from MSMA was readily absorbed from gastrointestinal tract and distributed in the body fluids and the various tissues. Approximately 90% of the arsenic was excreted in the urine within 120 hrs and small amounts were also recovered in feces. Arsenic accumulation in the tissues was low and urinary excretion was the most important exit route. Arsenic concentrations in milk were low when compared to the controls, which indicates that arsenic is not excreted in the milk to significant levels. The absorption, distribution and overall elimination rate constants for the two animal species studied were statistically different at the 0.95 level of confidence which indicates that there are apparently differences in MSMA metabolism by sheep and goats.     

THE APPLICATION OF RIDGE REGRESSION ANALYSIS TO A HYDROLOGIC TARGET-CONTROL MODEL1

ABSTRACT: Ridge regression analysis is used to investigate the stability of regression estimates over twenty-three years of data in a target-control model. Two target stations in the Wind River Range in Wyoming are studied using two sets of control variables. The predictive ability of ridge regression analysis is compared to that of ordinary regression analysis. The results of this study indicate improved stability of the estimates of ridge regression over ordinary regression. The predictive ability of the ridge regression estimates is as good or better than regression estimates.     

The regional nature of PM2.5 episodes in the upper Ohio River Valley

From October 1999 through September 2000, particulate matter (PM) with aerodynamic diameter > or =2.5 microm (PM2.5) mass and composition were measured at the National Energy Technology Laboratory Pittsburgh site, with a particle concentrator Brigham Young University-organic sampling system and a tapered element oscillating microbalance (TEOM) monitor. PM2.5 measurements had also been obtained with TEOM monitors located in the Pittsburgh, PA, area, and at sites in Ohio, including Steubenville, Columbus, and Athens. The PM data from all these sites were analyzed on high PM days; PM2.5 TEOM particulate mass at all sites was generally associated with transitions from locally high barometric pressure to lower pressure. Elevated concentrations occurred with transport of PM from outside the local region in advance of frontal passages as the local pressure decreased. During high-pressure periods, concentrations at the study sites were generally low throughout the study region. Further details related to this transport were obtained from surface weather maps and estimated back-trajectories using the hybrid single-particle Lagrangian integrated trajectory model associated with these time periods. These analyses indicated that transport of pollutants to the Pittsburgh site was generally from the west to the southwest. These results suggest that the Ohio River Valley and possible regions beyond act as a significant source of PM and its precursors in the Pittsburgh area and at the other regional sites included in this study.     

Boater preferences for beach characteristics downstream from Glen Canyon Dam, Arizona

Release flow decisions are increasingly being influenced by an array of social values, including those related to river-based recreation. A substantial portion of past recreation research on downstream impacts of dams has focused on variability of instream flows. This study complements past research by assessing user preferences for beach characteristics affected by long-term impacts of flow regimes. Based upon a study of three recreational user groups (private trip leaders, commercial passengers, and river guides) of the Colorado River in Grand Canyon, preferences for beach size, presence of shade on beach, and presence of vegetation on beach are examined. Results indicate that large size beaches with shade from trees are setting characteristics with highly reliable and strong user preferences. The multinomial regression models developed for each user group indicate that 80% of all respondents would choose beach campsites 800 m(2); results were the same regardless of respondents' past boating experience, boat type (i.e. oar or motorized), or group size. In addition, size of beach was consistently reported to be a trip feature of moderate importance to respondents' river trip. Implications of this research are related to future prospects for controlled floods (i.e. spike flows) released from Glen Canyon Dam.     

Studies into the formation of dioxins in the sintering process used in the iron and steel industry. 1. Characterisation of isomer profiles in particulate and gaseous emissions

Dioxin analyses using a DB5MS chromatography column are presented for samples of dust from an electrostatic precipitator and emissions from the main stack of a UK sinter plant. The analyses have been repeated using the SP2331 column, for which the elution order has been determined for the whole range of tetra to octachlorodibenzo-p-dioxins and dibenzofurans, and which provides a larger degree of separation than the DB5MS column. Polychlorinated dibenzofurans are present in significantly larger amounts in both the dust and stack emissions, and are the main contributors to the I-TEQ. Analysis using the SP2331 column for dioxins show considerable similarity to those of Bacher et al. for soot from a wood-burning fire, but differ markedly from those of Addink et al. for simulation of waste incineration. The similarities to Bacher's results are less for the dibenzofurans. Comparison of absolute concentrations with reported vapour pressures shows the retention of significant dioxin in the dust to involve mechanisms other than pure condensation.     

The effects of bayluscide and malathion on the survival of Schistosoma mansoni miracidia

Laboratory experiments were conducted to assess the toxic effects of bayluscide and malathion against Schistosoma mansoni miracidia. The results indicate that survival of miracidia varied with times of exposure and concentrations of tested chemicals. Statistical analyses reveal that LC5, LC50 and LC95 for bayluscide were 0.04 ppm, 0.06 ppm and 0.12 ppm after 2 hours of exposure; 0.02 ppm, 0.03 ppm and 0.06 ppm after 4 hours of exposure; and 0.01 ppm, 0.02 ppm and 0.04 ppm after 6 hours of exposure respectively. These data indicate that bayluscide is much more toxic to the first stage larvae of schistosomes than to snail intermediate hosts cited in the literature. Application of lower concentrations of molluscicide in the transmission sites is thus expected to curtail the survival of miracidia; therefore controlling schistosomiasis at relatively low costs. Such applications also reduce the risk of toxicity to non target organisms present in the aquatic environment. Statistical analysis of the results of tests using malathion gave LC5, LC50 and LC95 values of 83.38 ppm, 153.11 ppm and 245.85 ppm after 2 hours of exposure; and 76.86 ppm, 116.48 ppm and 172.04 ppm after 4 hours of exposure respectively. These data indicate that the use of malathion as an insecticide in tropical ecosystems may also affect the survival and viability of schistosome miracidia. Such uses could help reducing the risk of schistosomiasis transmission in these particular locations.