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201.
Contact calls are utilized by several bird and mammal species to maintain group cohesion and coordinate group movement. From
a signal design perspective, contact calls typically exhibit acoustic features that make them easily localizable and encode
information about individual or group identity. Pallid bats (Antrozous pallidus) are unusual among vespertilionids in that they often emit a loud, partially audible frequency-modulated social call several
times in rapid succession while in flight. This call appears to function as a contact call in that it is frequently given
when bats return from foraging and perform circular flights before entering a crevice roost. However, the degree to which
pallid bats respond to the calls of conspecifics and what information is provided in the call is unknown. Thus, the goal of
this study was to investigate pallid bat calling behavior to determine if calls attract roostmates or elicit responses from
them and provide sufficient information for individual recognition. In playback studies, we found that contact calls, elicit
calls, and approaches and that free-flying bats respond more to familiar than unfamiliar calls. In addition, analysis of frequency
and temporal measurements of calls collected from multiple sites and spectral cross correlation analysis of calls recorded
from the same radio-tagged bats on multiple evenings revealed that the frequency pattern of contact calls is highly repeatable
over time within individuals but exhibits significant differences among individuals. Thus, contact call structure appears
to be unique to individuals and stable through time, which makes these calls well-suited for roostmate recognition. 相似文献
202.
Giant honeybees (Apis dorsata) nest in the open and have developed a wide array of strategies for colony defence, including the Mexican wave-like shimmering behaviour. In this collective response, the colony members perform upward flipping of their abdomens in coordinated cascades across the nest surface. The time–space properties of these emergent waves are response patterns which have become of adaptive significance for repelling enemies in the visual domain. We report for the first time that the mechanical impulse patterns provoked by these social waves and measured by laser Doppler vibrometry generate vibrations at the central comb of the nest at the basic (=‘natural’) frequency of 2.156?±?0.042 Hz which is more than double the average repetition rate of the driving shimmering waves. Analysis of the Fourier spectra of the comb vibrations under quiescence and arousal conditions provoked by mass flight activity and shimmering waves gives rise to the proposal of two possible models for the compound physical system of the bee nest: According to the elastic oscillatory plate model, the comb vibrations deliver supra-threshold cues preferentially to those colony members positioned close to the comb. The mechanical pendulum model predicts that the comb vibrations are sensed by the members of the bee curtain in general, enabling mechanoreceptive signalling across the nest, also through the comb itself. The findings show that weak and stochastic forces, such as general quiescence or diffuse mass flight activity, cause a harmonic frequency spectrum of the comb, driving the comb as an elastic plate. However, shimmering waves provide sufficiently strong forces to move the nest as a mechanical pendulum. This vibratory behaviour may support the colony-intrinsic information hypothesis herein that the mechanical vibrations of the comb provoked by shimmering do have the potential to facilitate immediate communication of the momentary defensive state of the honeybee nest to the majority of its members. 相似文献
203.
204.
Dina K. N. Dechmann Elisabeth K. V. Kalko Gerald Kerth 《Behavioral ecology and sociobiology》2007,61(8):1219-1228
In polygynous mammals, males are usually responsible for gene flow while females are predominantly philopatric. However, there
is evidence that in a few mammalian species female offspring may disperse to avoid breeding with their father when male tenure
exceeds female age at maturity. We investigated offspring dispersal and local population structure in the Neotropical bat
Lophostoma silvicolum. The mating system of this species is resource defense polygyny, with the resource being active termite nests, excavated
by single males, which are then joined by females. We combined field observations of 14 harems during 3 years and data about
the genetic structure within and between these groups, calculated with one mitochondrial locus and nine nuclear microsatellite
loci. The results show that both male and female offspring disperse before maturity. In addition, we estimated life span of
excavated termite nests and the duration they were occupied by the same male. Our findings suggest that long male tenure of
up to 30 months is indeed a likely cause for the observed dispersal by female offspring that can reach maturity at a low age
of 6 months. We suggest that dispersal by offspring of both sexes may occur quite frequently in polygynous tropical bats and
thus generally may be more common in mammals than previously assumed. 相似文献
205.
206.
207.
Morris I. Schnitzer Carlos M. Monreal Gerald Jandl Peter Leinweber Peter B. Fransham 《Journal of environmental science and health. Part. B》2013,48(1):79-95
The initial chicken manure and the three fractions derived from it by fast pyrolysis, that is, the two biooils Fractions I and II as well as the residual char were analyzed by Curie-point pyrolysis-gas chromatography/mass spectrometry (Cp Py-GC/MS). The individual compounds identified were grouped into the following six compound classes: (a) N-heterocyclics; (b) substituted furans; (c) phenol and substituted phenols; (d) benzene and substituted benzenes; (e) carbocyclics; and (f) aliphatics. Of special interest were the relatively high concentrations of N-heterocyclics in biooil Fraction II which was obtained in the highest yield and had the highest calorific value. Prominent N-heterocyclics in biooil Fraction II were methyl-and ethyl-substituted pyrroles, pyridines, pyrimidine, pyrazines, and pteridine. Also noteworthy was the high abundance of aliphatics in biooil Fraction I and the char. The alkanes and alkenes in biooil Fraction I ranged from n-C7 to n-C18 and C7:1 to C18:1, respectively, and those in the char from n-C7 to n-C19 and C7:1 to C19:1, respectively. The N-heterocyclics in the two biooil Fractions came from the chicken manure, from proteinaceous materials during fast pyrolysis or were formed during the fast pyrolysis manure conversion by the Maillard reaction which involved the formation of N-heterocyclics by amino acids interacting with sugars. 相似文献
208.
Noncrop areas such as hedgerows in agricultural landscapes can perform several ecological and agronomic functions (e.g., habitat,
movement corridors, windbreak, etc.), but their dynamics and drivers of changes are often poorly known. We conducted a study
in three agricultural landscapes of southern Quebec, Canada, to assess and compare the spatial and temporal (1958–1997) dynamics
of three hedgerow networks in relation to geomorphic conditions (marine, glacial, and mixed deposit) and land-use changes.
Hedgerow networks were mapped and described in terms of their structure (density, degree of connectivity, and presence of
trees or shrubs) and their relationship to other components of the landscape (connection to woodland). Relationships were
assessed in time and space using nonparametric correlation, Mantel test, and principal components analysis (PCA). Results
show significant differences between hedgerow structure for the three landscapes and distinct temporal and spatial dynamics
that can be related to changes in management practices and agricultural policies. On marine deposits, increases in hedgerow
density did not always correspond to an increase in their degree of connectivity, suggesting a possible reduction in network
quality. On glacial deposits, hedgerow density declined following abandonment of agricultural land, but rather than disappearing,
these linear structures were integrated into adjacent brush or forested areas. Our analysis reveals the complex spatial and
temporal dynamics of the hedgerow networks and highlights the need to take into account spatial attributes such as connectivity
and connection to woodland to evaluate more accurately overall network quality. 相似文献
209.
This study proposes a model linking firm motivations for seeking ISO 14001 certification to the effectiveness of three major components of an environmental management system (EMS)--environmental policy, the assessment of environmental aspect and impacts, and management review. The relationship of these EMS components with a self-reported measure of environmental performance is also examined. From a sample of 29 ISO 14001 certified facilities in Hong Kong (of 71 total certifications at the time the data was collected), it was found that motivations to enhance firm reputation are positively related to perceptions of the effectiveness of the policy statement. Motivations for reputation enhancement and cost reduction were positively related to perceptions of EMS effectiveness in assessing environmental aspects and impacts. The effectiveness of the methodology for identifying environmental aspects and impacts was also found to be positively related to improved environmental performance. 相似文献
210.
Preferences for dealing with environmental problems: an empirical study of managers in three mainland Chinese cities 总被引:1,自引:0,他引:1
This study examines managerial preferences for various policy mechanisms commonly used to address environmental problems using a sample of 653 Chinese managers from firms in Beijing, Dalian and Guangzhou. Overall, these managers appeared to favor regulatory instruments, placing somewhat less faith in market and communicative instruments. However, all measures appear to have ample support within each subgroup. In addition, the influence of two situational factors on these preferences was investigated--the immediacy of environmental impact and diffusion of responsibility. The results of the study indicate that these two factors interact in explaining managerial preferences, but only for the use of market mechanisms. 相似文献