Global increases in environmental noise levels - arising from expansion of human populations, transportation networks, and resource extraction - have catalysed a recent surge of research into the effects of noise on wildlife. Synthesising a coherent understanding of the biological consequences of noise from this literature is challenging. Taxonomic groups vary in auditory capabilities. A wide range of noise sources and exposure levels occur, and many kinds of biological responses have been observed, ranging from individual behaviours to changes in ecological communities. Also, noise is one of several environmental effects generated by human activities, so researchers must contend with potentially confounding explanations for biological responses. Nonetheless, it is clear that noise presents diverse threats to species and ecosystems and salient patterns are emerging to help inform future natural resource-management decisions. We conducted a systematic and standardised review of the scientific literature published from 1990 to 2013 on the effects of anthropogenic noise on wildlife, including both terrestrial and aquatic studies. Research to date has concentrated predominantly on European and North American species that rely on vocal communication, with approximately two-thirds of the data set focussing on songbirds and marine mammals. The majority of studies documented effects from noise, including altered vocal behaviour to mitigate masking, reduced abundance in noisy habitats, changes in vigilance and foraging behaviour, and impacts on individual fitness and the structure of ecological communities. This literature survey shows that terrestrial wildlife responses begin at noise levels of approximately 40 dBA, and 20% of papers documented impacts below 50 dBA. Our analysis highlights the utility of existing scientific information concerning the effects of anthropogenic noise on wildlife for predicting potential outcomes of noise exposure and implementing meaningful mitigation measures. Future research directions that would support more comprehensive predictions regarding the magnitude and severity of noise impacts include: broadening taxonomic and geographical scope, exploring interacting stressors, conducting larger-scale studies, testing mitigation approaches, standardising reporting of acoustic metrics, and assessing the biological response to noise-source removal or mitigation. The broad volume of existing information concerning the effects of anthropogenic noise on wildlife offers a valuable resource to assist scientists, industry, and natural-resource managers in predicting potential outcomes of noise exposure.
Abstract.1. Relatively few studies of the host‐finding ability of specialised, phytophagous insects involve direct observations of individual insects moving among intact hosts and non‐hosts. Information from such studies can inform the design of restoration programmes for species of conservation concern.2. The movement of caterpillars of the threatened Oregon silverspot butterfly, Speyeria zerene hippolyta (Edwards) (Lepidoptera: Nymphalidae) was studied in the field in cleared arenas with 10 cm radii. Caterpillars were placed in the centre, surrounded by three individuals of their host, Viola adunca, and three different non‐host individuals, separated by bare ground. In a second experiment, second instars were placed between a host and a non‐host, 3–6 cm away. Caterpillars were observed to determine if they walked to their host more often than expected by chance.3. Caterpillars walked to vegetation significantly more often than expected by chance. They did not, however, reach their hosts more often than expected, based on plant availability.4. It is concluded that S. z. hippolyta caterpillars can distinguish vegetation from bare ground from 10 cm away. There is no evidence that they can distinguish their host plant from other herbaceous species at distances of 3 cm.
Studies of at-risk species are likely to have greater conservation impact if they: involve managers in question formulation, set specific management or restoration goals, and are based on detailed knowledge of species' resource needs. These ideas guided our investigation of the foraging behavior of larvae of a US federally threatened butterfly, the Oregon silverspot (Speyeria zerene hippolyta), with the goal of making management recommendations for habitat restoration. S. z. hippolyta larvae feed exclusively on Viola adunca and must consume multiple individuals to pupate successfully. Larvae forage at random through meadow vegetation to locate host plants. Observations of larvae foraging under field conditions revealed that larger, older larvae move more rapidly and turn less acutely than smaller, younger larvae; the consequence of these developmental differences is that younger larvae tend to remain in one place while older larvae tend to range more widely, presumably in search of new host plants.Results from a simulation model initialized with these data suggested that a host plant density of at least four V. adunca plants/m 2 (depending on predation intensity to which larvae are exposed) is required in order for 4th instar larvae to have a 10 % chance of survival to pupation. These findings are being used to guide a violet restoration program for this sensitive species.
Existing research has examined if undergraduate factors influence chemistry and physics, or physical science, doctoral degree entry and whether variables during PhD programs associate with graduation. Yet research on the transition from bachelor’s degree to doctoral degree entry (i.e., PhD entry in less than 6 months, attainment of a master’s degree prior to doctoral degree entry, or working in a science-related job for more than a year prior to doctoral degree entry) on PhD degree graduation remains scarce. Our study examines the transition from bachelor’s to doctoral degrees to see if experiences therein associate with female PhD graduation, after doctoral degree enrollment. Our logistic regression analysis, of female chemistry and physics doctorates ( n = 867), indicated that attainment of a master’s degree did not change the likelihood of graduation, when compared to direct entry into physical science doctoral programs. Meanwhile working in a science-related job for a year or more is associated with a significantly lower likelihood of physical science doctoral graduation when compared to women who entered directly into PhD programs or received a master’s degree prior to enrollment.
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