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431.
The aggressive and singing responses of ten territorial male song sparrows, Melospiza melodia, to sustained song-type matching via interactive playback were examined. This auditory stimulus, which involves both synchronous switching and song-type matching, was hypothesized to be a strong aggressive threat. Responses were compared to five other trial types in which the switching pattern and song-type similarity were independently varied. The six trial types were organized into a factorial design with three switching levels (no switching, synchronized switching, and rapid unsynchronized switching) and two matching levels (shared song-types and unshared song-types). The aggressive response of the birds, a composite index of the correlated behaviors of singing rate, perch change rate, and time spent close to the speaker, showed significant main effects of both the switching and the matching factors, with no interaction effect. The response was highest for the shared/unsynchronized switching trial and lowest for the unshared/no switching trial. Since the synchronous switching trials produced aggressive responses intermediate between the no switching and rapid unsynchronized switching trials, our results corroborate earlier studies showing that switching rate, song-type diversity and song similarity are the key determinants of aggressive approach. However, the switching rate of the focal birds during playback was not correlated with the other response variables and showed a very different pattern from the aggressive response. Switching rate increased during unshared/synchronized trials and decreased during shared/synchronized (i.e., song-type matching) trials. The tendency of the birds to refrain from switching when they were song-type matched by playback led to long bouts of matched-type countersinging. These results suggest that song-type matching locks two countersinging birds into a new level of interaction in which information other than aggressive motivation exchanged. 相似文献
432.
433.
Almeida Aleska Kaufmann de Almeida Isabel Kaufmann Guarienti José Antonio Gabas Sandra Garcia 《Environmental science and pollution research international》2022,29(6):8173-8173
Environmental Science and Pollution Research - 相似文献
434.
Reyes-Márquez Alejandra Aguíñiga-García Sergio Morales-García Sandra Soledad Sedeño-Díaz Jacinto Elías López-López Eugenia 《Environmental science and pollution research international》2022,29(41):61643-61661
Environmental Science and Pollution Research - Trophic transfer and bioaccumulation of trace metals have a profound impact on the structure and function of coastal areas; however, the metal... 相似文献
435.
O'Halloran J Irwin S Harrison S Smiddy P O'Mahony B 《Environmental pollution (Barking, Essex : 1987)》2003,123(1):85-93
A sample of 124 deserted/infertile dipper (Cinclus cinclus) eggs was collected in south-west Ireland during six seasons (1990-1994 and 1999) and analysed for mercury and organochlorines. Mercury was detected in three of the 6 years but no trend was observed. DDT occurred above the limit of detection in only two eggs, one each in 1993 and 1994. In contrast, two derivatives of DDT (DDE and TDE) were found much more commonly. DDE occurred in over 87% of eggs, while TDE contamination was less widespread and reached a maximum of 60% in 1993, with none detected in 1991 or 1999. There was no trend in occurrence of DDE or TDE across years. PCB contamination was present consistently over the 10-year period, with little change in the proportion of contaminated eggs collected over time. In all years, the lowest recorded occurrence of total PCBs was 69% expressed on a formulation basis as Arochlor 1254. PCB congeners 138, 153 and 180 dominated. The congener pattern was similar across years with the exception of 1990 when congener 118 dominated. A distinct trend of high values of contaminants was observed in 1990 and 1993. In 1990, PCB 118 was the dominant contaminant, while in 1993, HEOD, DDE, PCB 138 and PCB 153 were primary contributors to the observed result. Other contaminants (HCB, PCB 101, gamma-HCH, PCB 170 and PCB 180) showed little obvious patterns between years and occurred at relatively low levels. No pattern was observed in contaminants when eggs were grouped according to river or altitude. These data provide a baseline for organochlorine contamination levels in Irish freshwater ecosystems against which future trends can be assessed. 相似文献
436.
Phillip W. Albro J. Ronald Hass Carl C. Peck Sandra T. Jordan Jean T. Corbett Joanna Schroeder 《Journal of environmental science and health. Part. B》2013,48(6):701-714
Abstract The pervasiveness of the plasticizer di‐(2‐ethylhexyl) phthalate (DEHP) in the environment and especially in the laboratory results in a background that may cause severe interference with analytical studies. Animal‐to‐animal variability in the distribution of DEHP metabolites in excreta normally makes it necessary to use large groups of animals when different treatments are compared. Finally, radioactive tracers are usually considered undesirable for metabolic studies involving human subjects. All of these problems can be overcome through the use of muliple isotopic labels, especially 12C/13C/14C. Examples are given involving rats and monkeys, and applicability to humans is discussed. The principles involved are not limited to any particular class of test compounds. In rats, the competing pathways for metabolism of phthalate esters produce a different distribution of metabolites from a small intravenous dose of DEHP than from a large oral dose. 相似文献
437.
Penelope L. Diebel Daniel B. Taylor Sandra S. Batie Conrad D. Heatwole 《Journal of the American Water Resources Association》1992,28(4):755-761
ABSTRACT: Protection of ground water quality is of considerable importance to local, state, and federal governments. This study uses a 15-year mathematical programming model to evaluate the effectiveness of low-input agriculture, under alternative policy scenarios, as a strategy to protect ground water quality in Richmond County, Virginia. The analysis considers eight policy alternatives: cost-sharing for green manures, two restrictions on atrazine applications levels, chemical taxation, a restriction on potential chemical and nitrogen levels in ground water only and in surface and ground water, and two types of land retirement programs. The CREAMS and GLEAMS models were used to estimate nitrate and chemical leaching from the crop root zone. The economic model evaluates production practices, policy constraints, and water quality given a long-term profit maximizing objective. The results indicate that low-input agriculture alone may not be an effective ground water protection strategy. The policy impacts include partial adoption of low-input practices, land retirement, and the substitution of chemicals. Only mandatory land retirement policies reduced all chemical and nutrient loadings of ground water; however, they did not promote the use of low-input agricultural practices. 相似文献
438.
Hans Schreier Sandra Brown Margaret Schmidt Pravakar Shah Bubhan Shrestha Gopal Nakarmi Khagendra Subba Susanne Wymann 《Environmental management》1994,18(1):139-150
GIS overlay techniques were used to provide a quantitative historic documentation of deforestation and land-use dynamics in
the Middle Mountains of Nepal between 1947 and 1990. Deforestation was most critical in the 1960s, but active afforestation
programs in the 1980s have reversed the process. In spite of these trends, the degradation problem is more complex. The GIS
evaluation showed that 86% of the recently afforested land is now under pine plantations located primarily at lower elevations
and moderately steep slopes. In contrast, rainfed agricultural expansion is most pronounced on acidic soils and steeper, upper
elevation sites, suggesting marginalization of agriculture. Agricultural expansion coupled with major losses of grazing land
to pine forests are the key processes pointing towards major animal feed deficits. An alternative animal feed source is suggested
through GIS using a topographically based microclimatic classification to generate a tree-planting map where the optimum ecological
conditions for selective native fodder tree species are identified. 相似文献
439.
440.
Cruz JV Pacheco D Coutinho R Cymbron R Mendes S Antunes P Fontiela J Freire P 《Journal of environmental monitoring : JEM》2010,12(12):2216-2225
Chemical monitoring of water quality on a total of 16 rivers in the Azores archipelago (Portugal), since 2003, made it possible to identify the major pressures and spatial geochemical variations along main course of the rivers. River water pollution is to a large extent associated to point sources, namely domestic wastewater discharges, especially in urban areas, and diffuse sources, associated with pasture land, and explain the high values on BOD(5) and nutrients (P and N). Heavy metals and metalloids, as well as hydrocarbons and pesticides, are generally under the detection limits of the analytical methods. Generally, river water reflects pollution loads according to a simple model, derived from land use in the watershed: in the upper part conditions are pristine, in the intermediate portion of the basin pasture land dominates and near the coast urban discharges are increasingly important. Results stress the role that an approach based on the watershed scale, coupled with land use management measures, are crucial to water management procedures and a successful WFD implementation in small river basin districts like the Azores. The paper also shows the need for full compliance regarding EU directives on urban wastewater and nitrate pollution due to agriculture. 相似文献