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331.
Julia Delingat Franz Bairlein Anders Hedenström 《Behavioral ecology and sociobiology》2008,62(7):1069-1078
Behaviour on migration was often suggested to be selected for time-minimising strategies. Current optimality models predict
that optimal fuel loads at departure from stopover sites should increase with increasing fuel deposition rates. We modified
such models for the special case of the east Atlantic crossing of the Northern Wheatear (Oenanthe oenanthe). From optimality theory, we predict that optimal time-minimising behaviour in front of such a barrier should result in a
positive correlation between fuel deposition rates and departure fuel loads only above a certain threshold, which is the minimum
fuel load (f
min) required for the barrier crossing. Using a robust range equation, we calculated the minimum fuel loads for different barrier
crossings and predict that time-minimising wheatears should deposit a minimum of 24% fuel in relation to lean body mass (m
0
) for the sea crossing between Iceland and Scotland. Fuel loads of departing birds in autumn in Iceland reached this value
only marginally but showed positive correlation between fuel deposition rate (FDR) and departure fuel load (DFL). Birds at
Fair Isle (Scotland) in spring, which were heading towards Iceland or Greenland, were significantly heavier and even showed
signs of overloading with fuel loads up to 50% of lean body mass. Departure decisions of Icelandic birds correlated significantly
with favourable wind situations when assuming a migration direction towards Spain; however, the low departure fuel loads contradict
a direct non-stop flight. 相似文献
332.
333.
To balance advantages and disadvantages of group living, some species have fission-fusion social systems in which members of the same group form frequently changing subgroups. This allows flexible responses of group size to external conditions while at the same time retaining group stability. In chimpanzees, subgroup (party) size and composition depend mainly on the presence of receptive females, food availability and the activity of the party. Here we analyse the extent to which fission-fusion parameters are influenced by changes of demographic variables like community size and composition. Data were collected from a habituated West African chimpanzee community (Taï forest, Côte dIvoire) over 10 years, during which total community size decreased from 51 to 21, and the number of adult males decreased from 9 to 2. Taï chimpanzees are highly gregarious, as they spend more than 80% of their time with unrelated conspecifics. With decreasing community size, party size, party duration and male-female association increased. Neither activity nor the presence of receptive females or feeding competition could explain the observed changes in grouping patterns. Thus, the decrease in community size led to an increase of party cohesion and also enhanced cohesiveness between the sexes, while general sociality remained unchanged. Therefore, our data support the notion that small communities are more cohesive and have a less flexible fission-fusion system.Communicated by D. Watts 相似文献
334.
Graham W. Prescott William J. Sutherland Daniel Aguirre Matthew Baird Vicky Bowman Jake Brunner Grant M. Connette Martin Cosier David Dapice Jose Don T. De Alban Alex Diment Julia Fogerite Jefferson Fox Win Hlaing Saw Htun Jack Hurd Katherine LaJeunesse Connette Felicia Lasmana Cheng Ling Lim Antony Lynam Aye Chan Maung Benjamin McCarron John F. McCarthy William J. McShea Frank Momberg Myat Su Mon Than Myint Robert Oberndorf Thaung Naing Oo Jacob Phelps Madhu Rao Dietrich Schmidt‐Vogt Hugh Speechly Oliver Springate‐Baginski Robert Steinmetz Kirk Talbott Maung Maung Than Tint Lwin Thaung Salai Cung Lian Thawng Kyaw Min Thein Shwe Thein Robert Tizard Tony Whitten Guy Williams Trevor Wilson Kevin Woods Alan D. Ziegler Michal Zrust Edward L. Webb 《Conservation biology》2017,31(6):1257-1270
Political and economic transitions have had substantial impacts on forest conservation. Where transitions are underway or anticipated, historical precedent and methods for systematically assessing future trends should be used to anticipate likely threats to forest conservation and design appropriate and prescient policy measures to counteract them. Myanmar is transitioning from an authoritarian, centralized state with a highly regulated economy to a more decentralized and economically liberal democracy and is working to end a long‐running civil war. With these transitions in mind, we used a horizon‐scanning approach to assess the 40 emerging issues most affecting Myanmar's forests, including internal conflict, land‐tenure insecurity, large‐scale agricultural development, demise of state timber enterprises, shortfalls in government revenue and capacity, and opening of new deforestation frontiers with new roads, mines, and hydroelectric dams. Averting these threats will require, for example, overhauling governance models, building capacity, improving infrastructure‐ and energy‐project planning, and reforming land‐tenure and environmental‐protection laws. Although challenges to conservation in Myanmar are daunting, the political transition offers an opportunity for conservationists and researchers to help shape a future that enhances Myanmar's social, economic, and environmental potential while learning and applying lessons from other countries. Our approach and results are relevant to other countries undergoing similar transitions. 相似文献
335.
336.
Kitchen Dawn M. Seyfarth Robert M. Fischer Julia Cheney Dorothy L. 《Behavioral ecology and sociobiology》2003,53(6):374-384
Adult male baboons (Papio cynocephalus) give loud two-syllable 'wahoo' calls during dawn choruses, interactions between groups, when chasing females, and in aggressive interactions with other males. These 'contest' wahoos are acoustically different from 'alarm' wahoos given to predators. In a study of free-ranging baboons in the Okavango Delta, Botswana, we found no significant correlations between the acoustic features of wahoos and adult male size; however, acoustic features were correlated with male dominance rank, age, and calling bout length. Here we show that other measures of calling behavior also appear to function as honest indicators of stamina and competitive ability. High-ranking males were more likely than middle- or low-ranking males to participate in wahoo bouts. They called at significantly higher rates, and their bouts were longer and contained more calls. All males were significantly more likely to participate in wahoo bouts with another male if their opponent's rank was similar to their own. Bouts involving males of similar ranks were longer, contained more wahoos, and involved calling at higher rates, than other bouts. In contests between males of similar ranks, the subordinate and dominant were equally likely to end the bout, whereas in contests involving males of disparate ranks, subordinates were significantly more likely to end the bout. Bouts involving males of similar rank were significantly more likely than others to escalate and result in physical fighting. 相似文献
337.
Alice A. Han Emily B. Fabyanic Julie V. Miller Maren S. Prediger Nicole Prince Julia A. Mouch Jonathan Boyd 《Environmental monitoring and assessment》2017,189(4):190
Thousands of gallons of industrial chemicals, crude 4-methylcyclohexanemethanol (MCHM) and propylene glycol phenyl ether (PPh), leaked from industrial tanks into the Elk River in Charleston, West Virginia, USA, on January 9, 2014. A considerable number of people were reported to exhibit symptoms of chemical exposure and an estimated 300,000 residents were advised not to use or drink tap water. At the time of the spill, the existing toxicological data of the chemicals were limited for a full evaluation of the health risks, resulting in concern among those in the impacted regions. In this preliminary study, we assessed cell viability and plasma membrane degradation following a 24-h exposure to varying concentrations (0–1000 μM) of the two compounds, alone and in combination. Evaluation of different cell lines, HEK-293 (kidney), HepG2 (liver), H9c2 (heart), and GT1-7 (brain), provided insight regarding altered cellular responses in varying organ systems. Single exposure to MCHM or PPh did not affect cell viability, except at doses much higher than the estimated exposure levels. Certain co-exposures significantly reduced metabolic activity and increased plasma membrane degradation in GT1-7, HepG2, and H9c2 cells. These findings highlight the importance of examining co-exposures to fully understand the potential toxic effects. 相似文献
338.
Alex R. Gholson Julia F. Storm R. K. M. Jayanty Robert G. Fuerst Thomas J. Logan M. Rodney Midgett 《Journal of the Air & Waste Management Association (1995)》2013,63(9):1210-1217
Regulation to control air emissions of toxic organic compounds require the collection and analysis of effluent gas from low level sources such as hazardous waste incinerators. The standard SW- 846 Method specifies the use of Tenax and Tenax/charcoal adsorbent traps for collection of volatile organics from incinerators. This study evaluates passivated stainless steel canisters as an alternative to adsorbent traps to eliminate some of the problems associated with adsorbent sampling. Initially the stability of 18 nonpolar, volatile organic compounds was determined in Summa-treated stainless steel canisters with greater than 100 ppmv HCI and saturated with water vapor. All 18 components were stable for a twoweek period; however, an Interference caused a 10-fold increase In the FID response of trlchloroethylene, toluene, and chlorobenzene. No Interference of the ECD response was found for any of the 11 compounds detected with the ECD including trlchloroethylene. A pilot scale incinerator was sampled using canisters, and the destruction efficiency of 1,1,1-trichloroethane was determined at a concentration of less than 0.5 ppbv while determining 1,1-dichloroethylene, the major product of Incomplete combustion, at a concentration of 8000 ppbv from the same sample. 相似文献
339.
We assessed the relationship between riparian management and stream quality along five southeastern Minnesota streams in 1995
and 1996. Specifically, we examined the effect of rotationally and continuously grazed pastures and different types of riparian
buffer strips on water chemistry, physical habitat, benthic macroinvertebrates, and fish as indicators of stream quality.
We collected data at 17 sites under different combinations of grazing and riparian management, using a longitudinal design
on three streams and a paired watershed design on two others. Continuous and rotational grazing were compared along one longitudinal
study stream and at the paired watershed. Riparian buffer management, fenced trees (wood buffer), fenced grass, and unfenced
rotationally grazed areas were the focus along the two remaining longitudinal streams. Principal components analysis (PCA)
of water chemistry, physical habitat, and biotic data indicated a local management effect. The ordinations separated continuous
grazing from sites with rotational grazing and sites with wood buffers from those with grass buffers or rotationally grazed
areas. Fecal coliform and turbidity were consistently higher at continuously grazed than rotationally grazed sites. Percent
fines in the streambed were significantly higher at sites with wood buffers than grass and rotationally grazed areas, and
canopy cover was similar at sites with wood and grass buffers. Benthic macroinvertebrate metrics were significant but were
not consistent across grazing and riparian buffer management types. Fish density and abundance were related to riparian buffer
type, rather than grazing practices. Our study has potentially important implications for stream restoration programs in the
midwestern United States. Our comparisons suggest further consideration and study of a combination of grass and wood riparian
buffer strips as midwestern stream management options, rather than universally installing wood buffers in every instance.
RID=" ID=" The Unit is jointly sponsored by the US Geological Survey, Biological Resources Division; the Minnesota Department
of Natural Resources; the University of Minnesota; and the Wildlife Management Institute. 相似文献
340.
AbstractEuropean cities have emerged as laboratories for ‘sustainable mobility'. In the last few years, they have supported numerous electric car projects which combine clean engine technologies with offers on public or shared mobility. This paper compares two ongoing public electric car services in Berlin (BeMobility) and Paris (Autolib’). We explain how both projects shape future visions of sustainable mobility and transform regional transport systems in specific ways through their performative impact as local transport policy tools. Focusing on the socio-economic and political processes through which both projects were conceived and put into practice, we explain their differences as they reflect participating actors' interests in a French versus German industrial and transport policy context after the economic crisis in 2008. We find that whereas BeMobility integrates electric cars as one element in Berlin's intermodal transport system, and thus is centred around ‘intermodality' as the central vision of sustainable transport, Autolib’ in Paris essentially reproduces the dominant mode of private passenger car transport through adding a shared electric car fleet. 相似文献