Do yellow-bellied marmots respond to predator vocalizations?

We conducted four experiments to determine whether yellow-bellied marmots, Marmota flaviventris, discriminate among predator vocalizations, and if so, whether the recognition mechanism is learned or experience-independent. First, we broadcast to marmots the social sounds of coyotes, Canis latrans, wolves, Canis lupus, and golden eagles, Aquila chrysaetos, as well as conspecific alarm calls. Coyotes and eagles are extant predators at our study site, while wolves have been absent since the mid-1930s. In three follow-up experiments, we reversed the eagle call and presented marmots with forward and reverse calls to control for response to general properties of call structure rather than those specifically associated with eagles, we tested for novelty by comparing responses to familiar and unfamiliar birds, and we tested for the duration of predator sounds by comparing a wolf howl (that was much longer than the coyote in the first experiment) with a long coyote howl of equal duration to the original wolf. Marmots suppressed foraging and increased looking most after presentation of the conspecific alarm call and least after that of the coyote in the first experiment, with moderate responses to wolf and eagle calls. Marmots responded more to the forward eagle call than the reverse call, a finding consistent with a recognition template. Marmots did not differentiate vocalizations from the novel and familiar birds, suggesting that novelty itself did not explain our results. Furthermore, marmots did not differentiate between a wolf howl and a coyote howl of equal duration, suggesting that the duration of the vocalizations played a role in the marmots’ response. Our results show that marmots may respond to predators based solely on acoustic stimuli. The response to currently novel wolf calls suggests that they have an experience-independent ability to identify certain predators acoustically. Marmots’ response to predator vocalizations is not unexpected because 25 of 30 species in which acoustic predator discrimination has been studied have a demonstrated ability to respond selectively to cues from their predators.     

Human dimensions of environmental change in small island developing states: some common themes

Regional Environmental Change - Climate change and its consequence of sea level rise are major issues for small island developing states (SIDS), as they worsen many other pressures on their people...     

A comparison of employment growth and stability before and after the Fort Worth tornado

This study examined the time series pattern of employment growth and stability in Fort Worth, Texas taking into account the March 28, 2000 tornado. The tornado is treated econometrically as an intervention and both the mean and conditional variance of employment growth were estimated. Overall, this regional labor market experienced a decline in the employment growth rate following the tornado. Among the sectors that exhibited differences in employment dynamics between the pre- and post-tornado periods, the mining sector experienced a significant increase in employment growth following the tornado while the service andwholesale, retail trade sectors experienced significant declines in employment growth in the post-tornado period. The manufacturing, service, and wholesale, retail trade sectors were characterized by greater stability (i.e., a lower level of employment growth volatility) in the post-tornado period than in the pre-tornado period. Interestingly, in several sectors, no differences in the time series dynamics of employment growth were detected between the pre- and post-tornado periods. These sectors included construction, finance, insurance, real estate, government, and transportation and public utilities.     

Community-based observing networks and systems in the Arctic: Human perceptions of environmental change and instrument-derived data

Regional Environmental Change - Many papers have addressed the differing approaches to observation by scientists collecting instrumented data and by community or local knowledge-based observations....     

An attractive male trait and aggressiveness are negatively correlated in wild field crickets, but uncorrelated in lab-reared crickets

It is generally thought that attractive male traits are positively correlated with dominance (aggressiveness). However, growing evidence suggests that this is not necessarily the case. We investigated whether calling song, a male mating display used by females to evaluate potential mates in a field cricket (Gryllus integer), is correlated with aggressiveness. In this species, females prefer males with longer durations of singing time. We measured singing time by measuring song over three continuous days using a custom-designed audio-monitor and assessed aggressiveness by pairing males in agonistic interactions. Our results showed that for males caught in the field, the percentage of time spent singing was negatively correlated with aggressiveness. However, in males that were raised in the laboratory, the percentage of time spent singing was not correlated with aggressiveness. Since calling duration is an attractive male trait in these crickets, our data show that the attractiveness of males can be either negatively related to aggressiveness (field) or unrelated to aggressiveness (lab). Neither of these results fit the traditional view that preferred male mating cues should be positively correlated with dominance (aggressiveness). These results also suggest that measurements of aggressiveness made in the lab do not necessarily correspond with aggressiveness in the field.     

Energetics of mixing for the filling box and the emptying-filling box

The mixing efficiency of a plume in a filling box and an emptying-filling box is calculated for both transient and steady states. The mixing efficiency of a plume in a filling box in an asymptotic state is 1/2, independent of the details of this state or how the plume is modelled. The mixing efficiency of a plume in an emptying-filling box in steady state is \(1 - \xi \), where \(\xi = h/H\), the depth of the ambient layer h normalised by the height of the box H. A deeper mixed layer therefore corresponds to a higher mixing efficiency. These results shed light on the interpretation of mixing efficiencies of open and closed systems.

     

Evaluation of the SAPRC-07 mechanism against CSIRO smog chamber data

The updated SAPRC-07 mechanism was evaluated against data from experiments performed in the CSIRO smog chamber. The mechanism predictions have been compared to experimental results as well as predictions by SAPRC-99.Experiments were performed using either toluene or m-xylene in the presence of NO_x at sub-0.1 ppmv concentrations. For the majority of m-xylene experiments, the modelled Δ(O₃–NO) concentration was within 20% of observed values for both SAPRC mechanisms. However during the oxidation of toluene the production of radicals was poorly predicted, with final Δ(O₃–NO) concentration under-predicted by up to 60%. The predictions of major oxidants from isoprene oxidation were in good agreement with observed values. For the NO_x-limited conditions however, the ozone concentration predicted by both mechanisms were under-predicted by approximately 20% in the five experiments tested.The performance of the SAPRC-07 mechanism was also evaluated against twelve evaporated fuel experiments. Two types of evaporative mode experiments were performed: headspace evaporated fuel and wholly evaporated fuel. The major difference was a significantly higher concentration of aromatic hydrocarbons and larger alkane products in wholly evaporated fuels. For headspace evaporated fuel experiments both SAPRC mechanisms were in good agreement with experimental results. For wholly evaporated experiments the average Δ(O₃–NO) model error was ?25% with SAPRC-07 compared to less than ?5% for SAPRC-99. Updates to the photolysis data for dicarbonyls, the light source used and the experimental conditions under which these experiments were performed are possible causes for the discrepancy between SAPRC-99 and -07 predictions for wholly evaporated experiments.     

Chlorinated Solvent Treatment Wetland

A first‐of‐its‐kind wetland restoration project was completed in October 2000 to treat trichloroethene‐(TCE‐)impacted groundwater from a former manufacturing facility prior to discharge into a highly valued recreational surface water body in the upper Midwest. This article summarizes the design, construction, operation, and effectiveness of the restored wetland. The groundwater‐surface water discharge zone at the site was restored as a wetland to improve the natural degradation of TCE and subsequent degradation by‐products. For the past 11 years, the treatment wetland performance was evaluated by monitoring the wetland vegetation, wetland hydraulics, and water chemistry. Water quality data have been used to assess the wetland geochemistry, TCE and TCE‐degradation by‐product concentrations within the wetland, and the surface water quality immediately downgradient of the wetland. The treatment wetland has been performing according to design, with TCE and TCE‐degradation by‐products not exceeding surface water criteria. The monitoring results show that TCE and TCE‐degradation by‐products are entering the treatment wetland via natural hydraulic gradients and that the geochemistry of the wetland supports both reductive dechlorination (anaerobic degradation) and cometabolic degradation (aerobic degradation) of TCE and TCE‐degradation by‐products: cis‐ and trans‐1,2‐dichloroethene and vinyl chloride. © 2013 Wiley Periodicals, Inc.