1,890 research outputs found

    Crocodiles as dinosaurs: Behavioural thermoregulation in very large ectotherms leads to high and stable body temperatures

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    Empirical field data describing daily and seasonal cycles in body temperature (Tb) of free-ranging Crocodylus porosus (32-1010 kg) can be predicted by a mathematical analysis. The analysis provides a mechanistic explanation for the decreased amplitude of daily cycles in Tb and the increase in 'average' Tb with increasing mass. Assessments of 'average' daily Tb were made by dividing the integral of the difference between measured values of Tb and minimum operative temperature by the period of integration, to yield a thermal index expressing relative 'warmth' of crocodiles. The average daily Tb of a 1010 kg crocodile was 3.7 degrees C warmer than that of a 42 kg individual in summer and 1.9 degreesC warmer than that of a 32 kg individual in winter. The success of this mathematical approach confirms that crocodiles are simple ectotherms and that there is unlikely to be a significant contribution to their thermal biology from physiological mechanisms. Behaviour, however, is very important even in large individuals. Crocodiles in the field typically move daily between land and water in cycles that vary seasonally. We predicted Tb for the reverse of these behavioural cycles, which more than doubled seasonal fluctuations in Tb compared with the observed fluctuations. We were also able to predict the Tb of very large, dinosaur-sized crocodiles in a similar climate to that at our study site. A 10 000 kg 'crocodile', for example, would be expected to have a Tb of 31 degreesC in winter, varying by less than 0.1 degrees C during a day when operative temperatures varied by nearly 20 degrees C, from 20 to 38 degrees C. The study confirms that, in low latitudes at least, large dinosaurs must have had an essentially high and stable value of Tb, without any need for endothermy. Also, access to shade or water must have been crucial for the survival of large dinosaurs at low latitudes. Furthermore, the finding of increasing 'average' Tb as ectotherms grow larger may have implications for the metabolic rates of very large reptiles, because the Q10 effect could counteract the downscaling of metabolic rate with mass, an effect that seems not to have been recognised previously

    Spatial and seasonal relationships between Pacific harbor seals (Phoca vitulina richardii) and their prey, at multiple scales

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    Knowing where pinnipeds forage is vital to managing and protecting their populations, and for assessing potential interactions with fisheries. We assessed the spatial relationship between the seasonal distribution of Pacific harbor seals (Phoca vitulina richardii) outfitted with satellite transmitters and the seasonal distributions of potential harbor seal prey species in San Francisco Bay, California. Pearson’s correlation coefficients were calculated between the number of harbor seal locations in an area of the San Francisco Bay and the abundance of specific prey species in the same area. The influence of scale on the analyses was assessed by varying the scale of analysis from 1 to 10 km. There was consistency in the prey species targeted by harbor seals year-round, although there were seasonal differences between the most important prey species. The highest correlations between harbor seals and their prey were found for seasonally abundant benthic species, located within about 10 km of the primary haul-out site. Probable foraging habitat for harbor seals was identified, based on areas with high abundances of prey species that were strongly correlated with harbor seal distribution. With comparable local data inputs, this approach has potential application to pinniped management in other areas, and to decisions about the location of marine reserves designed to protect these species

    Application of an Ultralight Aircraft to Aerial Surveys of Kangaroos on Grazing Properties

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    A Drifter ultralight aircraft was used as a platform for line-transect aerial surveys of three species of kangaroo in the sheep rangelands south-east of Blackall and north of Longreach in central-western Queensland in winter 1993 and 1994. Favourable comparisons between the results of ultralight surveys and those made from a helicopter flying the same transects and foot surveys along another set of transects, all within a few days of the ultralight survey, confirmed the expectation we had that an ultralight would be a satisfactory and much cheaper vehicle for conducting aerial surveys of kangaroos. The comparisons are even more favourable when data for the three species surveyed are combined, pointing to a problem in species identification and underlining the importance of using only experienced observers for aerial survey of kangaroos, whatever the platform. The use of an ultralight aircraft could have particular value where a comparatively small area, such as an individual sheep or cattle property, is under consideration. In this paper, we present the numerical comparisons, along with an evaluation of the practicability of using this type of aircraft. We also describe a possible future scenario in which an accreditation process could see approved kangaroo surveyors undertaking property assessments by ultralight, under contract to graziers or other interested parties

    Nineteen Years of Public Opinion: The Boise State University Annual Public Policy Survey

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    Evidence suggests that public opinion has a significant and measurable impact on legislative, executive, and citizen interaction. The state of Idaho is no exception. In this white paper, we examine a sample of the opinions of Idahoans, as expressed in the Public Policy Survey, over the past nineteen years

    Evolution of smart devices and human movement apps: Recommendations for use in sports science education and practice

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    Many smart phones and tablets possess high-speed cameras. An increasing number of human movement professionals (e.g. personal trainers, athletics coaches, strength and conditioning coaches and physiotherapists) are beginning to use human movement analysis apps with their smart phones/tablets to quantitatively assess their clients’ performance and injury risk. However, an understanding of the validity and reliability of these tools is required. This narrative review seeks to list some relevant human movement apps; summarise the validity and reliability of selected apps and to provide recommendations for their use ineducation and practice

    Development of a drainage and flood control management program for urbanizing communities. Part I

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    Submitted to Office of Water Research and Technology, U.S. Dept. of Interior.Bibliography: pages [29]-41.September 1978.Urbanization causes an alteration of the stormwater runoff response of the urbanizing watershed which, in turn, increases stormwater damages downstream. Few communities have successfully implemented programs for managing these development induced drainage impacts due in part to the uncertainties associated with any drainage management program. Which rainfall-runoff model should be used, how sensitive is project analysis to poor discharge prediction, how should project cost be allocated, and so on. The objective of this research is to clarify these uncertainties and develop a readily implementable drainage and flood control management program for the mitigation of development-induced drainage impacts. These objectives are realized through a detailed examination of and recommendation on the three major elements of a drainage management program: the Technical element which establishes the method of flood hydrology calculation, the Financial element which establishes the methods for drainage and flood control cost calculation and cost allocation, and the Regulatory element which establishes the enforcement mechanism of the drainage management program. The recommended Technical element is based on the sensitivity of project analysis to poor runoff prediction, and on the predictive capability of various rainfall-runoff models. This predictive capability was evaluated for some of the more popular rainfall-runoff models through a statistical analysis of published results from those models. The recommended Financial element is based on a thorough review of the legal issues regarding: 1) municipal and developer liability with respect to development-induced drainage impacts, 2) project cost calculation, and 3) project cost apportionment. A new approach for apportioning drainage and flood control facility costs between developers and the municipal government is presented. The approach utilizes existing engineering analysis techniques to divide project costs in proportion to the reduced liability attributable to the developers and to the municipal government. Two Regulatory elements are proposed for the drainage management program. The changes to existing legislation that are necessary to enforce the drainage management program under the proposed regulatory component are discussed and sample legislation is included for each. The report is divided into two parts. Part II is the complete project report with detailed discussions of the methods and data used, and of the research findings. Part I is written as a user publication. It summarizes the research methods and results, and discusses the recommended drainage management program.OWRT Project no. B-161-COLO; supported in part by funds provided by the United States Department of the Interior, Office of Water Research and Technology, as authorized by the Water Resources Research Act of 1964, and pursuant to Grant Agreement No.(s) 14-34-0001-7112; and in part by funds provided by the Urban Drainage and Flood Control District, Denver, Colorado; and in part by the City of Lakewood, Colorado
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