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排序方式: 共有127条查询结果,搜索用时 15 毫秒
1.
MATTHEW W. MCKOWN JOSHUA T. ACKERMAN COLLIN A. EAGLES‐SMITH BERNIE R. TERSHY DONALD A. CROLL 《Conservation biology》2014,28(4):1100-1108
Although wildlife conservation actions have increased globally in number and complexity, the lack of scalable, cost‐effective monitoring methods limits adaptive management and the evaluation of conservation efficacy. Automated sensors and computer‐aided analyses provide a scalable and increasingly cost‐effective tool for conservation monitoring. A key assumption of automated acoustic monitoring of birds is that measures of acoustic activity at colony sites are correlated with the relative abundance of nesting birds. We tested this assumption for nesting Forster's terns (Sterna forsteri) in San Francisco Bay for 2 breeding seasons. Sensors recorded ambient sound at 7 colonies that had 15–111 nests in 2009 and 2010. Colonies were spaced at least 250 m apart and ranged from 36 to 2,571 m2. We used spectrogram cross‐correlation to automate the detection of tern calls from recordings. We calculated mean seasonal call rate and compared it with mean active nest count at each colony. Acoustic activity explained 71% of the variation in nest abundance between breeding sites and 88% of the change in colony size between years. These results validate a primary assumption of acoustic indices; that is, for terns, acoustic activity is correlated to relative abundance, a fundamental step toward designing rigorous and scalable acoustic monitoring programs to measure the effectiveness of conservation actions for colonial birds and other acoustically active wildlife. La Actividad Vocal como un Índice Escalable y de Bajo Costo del Tamaño de Colonia de las Aves Marinas 相似文献
2.
Effectiveness of Scat‐Detection Dogs in Determining Species Presence in a Tropical Savanna Landscape
CARLY VYNNE JOHN R. SKALSKI RICARDO B. MACHADO MARTHA J. GROOM ANAH T. A. JÁCOMO JADER MARINHO‐FILHO MARIO B. RAMOS NETO CRISTINA POMILLA LEANDRO SILVEIRA HEATH SMITH SAMUEL K. WASSER 《Conservation biology》2011,25(1):154-162
Abstract: Most protected areas are too small to sustain populations of wide‐ranging mammals; thus, identification and conservation of high‐quality habitat for those animals outside parks is often a high priority, particularly for regions where extensive land conversion is occurring. This is the case in the vicinity of Emas National Park, a small protected area in the Brazilian Cerrado. Over the last 40 years the native vegetation surrounding the park has been converted to agriculture, but the region still supports virtually all of the animals native to the area. We determined the effectiveness of scat‐detection dogs in detecting presence of five species of mammals threatened with extinction by habitat loss: maned wolf (Chrysocyon brachyurus), puma (Puma concolor), jaguar (Panthera onca), giant anteater (Myrmecophaga tridactyla), and giant armadillo (Priodontes maximus). The probability of scat detection varied among the five species and among survey quadrats of different size, but was consistent across team, season, and year. The probability of occurrence, determined from the presence of scat, in a randomly selected site within the study area ranged from 0.14 for jaguars, which occur primarily in the forested areas of the park, to 0.91 for maned wolves, the most widely distributed species in our study area. Most occurrences of giant armadillos in the park were in open grasslands, but in the agricultural matrix they tended to occur in riparian woodlands. At least one target species occurred in every survey quadrat, and giant armadillos, jaguars, and maned wolves were more likely to be present in quadrats located inside than outside the park. The effort required for detection of scats was highest for the two felids. We were able to detect the presence for each of five wide‐ranging species inside and outside the park and to assign occurrence probabilities to specific survey sites. Thus, scat dogs provide an effective survey tool for rare species even when accurate detection likelihoods are required. We believe the way we used scat‐detection dogs to determine the presence of species can be applied to the detection of other mammalian species in other ecosystems. 相似文献
3.
4.
THOMAS BROQUET SONIA ANGELONE JULIE JAQUIERY PIERRE JOLY JEAN‐PAUL LENA THIERRY LENGAGNE SANDRINE PLENET EMILIEN LUQUET NICOLAS PERRIN 《Conservation biology》2010,24(6):1596-1605
Abstract: Connectivity among populations plays a crucial role in maintaining genetic variation at a local scale, especially in small populations affected strongly by genetic drift. The negative consequences of population disconnection on allelic richness and gene diversity (heterozygosity) are well recognized and empirically established. It is not well recognized, however, that a sudden drop in local effective population size induced by such disconnection produces a temporary disequilibrium in allelic frequency distributions that is akin to the genetic signature of a demographic bottleneck. To document this effect, we used individual‐based simulations and empirical data on allelic richness and gene diversity in six pairs of isolated versus well‐connected (core) populations of European tree frogs. In our simulations, population disconnection depressed allelic richness more than heterozygosity and thus resulted in a temporary excess in gene diversity relative to mutation drift equilibrium (i.e., signature of a genetic bottleneck). We observed a similar excess in gene diversity in isolated populations of tree frogs. Our results show that population disconnection can create a genetic bottleneck in the absence of demographic collapse. 相似文献
5.
ADAM C. D. BARLOW CHRISTINA J. GREENWOOD ISHTIAQ U. AHMAD JAMES L. D. SMITH 《Conservation biology》2010,24(5):1338-1347
Abstract: Human–carnivore conflict is manifested in the death of humans, livestock, and carnivores. The resulting negative local attitudes and retribution killings imperil the future of many endangered carnivores. We tailored existing management tools to create a framework to facilitate the selection of actions to alleviate human–carnivore conflict and applied the framework to the human–tiger conflict in the Bangladesh Sundarbans. We identified potential actions that consider previous management efforts, local knowledge, cost‐effectiveness, fieldwork experience of authors and project staff, previous research on tiger ecology by the authors, and recommendations from human–carnivore conflict studies in other countries. Our framework includes creation of a profile to improve understanding of the nature of the conflict and its underlying causality. Identified actions include deterrents, education, direct tiger management, and response teams. We ranked actions by their potential to reduce conflict and the monetary cost of their implementation. We ranked tiger‐response teams and monitoring problem tigers as the two best actions because both had relatively high impact and cost‐effectiveness. We believe this framework could be used under a wide range of human–wildlife conflict situations because it provides a structured approach to selection of mitigating actions. 相似文献
6.
PAUL WEINDLING 《Disasters》1994,18(3):203-212
The transformation of the ethos of children's relief organisations from sentimentalism into science was reflected in the rise of nutritional science, eugenics, child psychology and child guidance. A related transition occurred in the organisational forms of child welfare organisations: with the rise of welfare states, government organisations took an increasing role. Internationally there was a move to expand the scope of charities relieving children in distress to broader strategies promoting child welfare. In this paper I consider these shifts in the case of international measures to relieve child starvation and to promote child welfare between the First and Second World Wars. I examine how health organisations had to move away from relief work and establish programmes seeking to relate the developing scientific understanding of nutrition to a range of factors affecting health. 相似文献
7.
Vellidis G Smith MC Leibowitz SG Ainslie WB Pruitt BA 《Environmental management》2003,31(2):0301-0312
In a climate of limited resources, it is often necessary to prioritize restoration efforts geographically. The synoptic approach
is an ecologically based tool for geographic prioritization of wetland protection and restoration efforts. The approach was
specifically designed to incorporate best professional judgment in cases where information and resources are otherwise limited.
Synoptic assessments calculate indices for functional criteria in subunits (watersheds, counties, etc.) of a region and then
rank the subunits. Ranks can be visualized in region-scale maps which enable managers to identify areas where efforts optimize
functional performance on a regional scale. In this paper, we develop a conceptual model for prioritizing watersheds whose
wetlands can be restored to reduce total sediment yield at the watershed outlet. The conceptual model is designed to rank
watersheds but not individual wetlands within a watershed. The synoptic approach is valid for applying the sediment yield
reduction model because there is high demand for prioritizing disturbed wetlands for restoration, but there is limited, quantitative,
accurate information available with which to make decisions. Furthermore, the cost of creating a comprehensive database is
prohibitively high. Finally, because the model will be used for planning purposes, and, specifically, for prioritizing based
on multiple decisions rather than optimizing a single decision, the consequence of prioritization errors is low. Model results
cannot be treated as scientific findings. The conclusions of an assessment are based on judgement, but this judgement is guided
by scientific principles and a general understanding of relevant ecological processes. The conceptual model was developed
as the first step towards prioritizing of wetland restoration for sediment yield reduction in US EPA Region 4. 相似文献
8.
The hydrogeomorphic (HGM) approach to wetland classification and functional assessment is becoming more widespread in the
United States but its use has been limited by the length of time needed to develop appropriate data sets and functional assessment
models. One particularly difficult aspect is the transferability among geographic regions of specific models used to assess
wetland function. Sharing of models could considerably shorten development and implementation of HGM throughout the United
States and elsewhere. As hydrology is the driving force behind wetland functions, we assessed the comparability of hydrologic
characteristics of three HGM subclasses (slope, headwater floodplain, mainstem floodplain) using comparable long-term hydrologic
data sets from different regions of the United States (Ridge and Valley Province in Pennsylvania and the Willamette Valley
in Oregon). If hydrology by HGM subclass were similar between different geographic regions, it might be possible to more readily
transfer extant models between those regions. We found that slope wetlands (typically groundwater-driven) had similar hydrologic
characteristics, even though absolute details (such as depth of water) differed. We did not find the floodplain subclasses
to be comparable, likely due to effects of urbanization in Oregon, regional differences in soils and, perhaps, climate. Slight
differences in hydrology can shift wetland functions from those mediated by aerobic processes to those dominated by anaerobic
processes. Functions such as nutrient cycling can be noticeably altered as a result. Our data suggest considerable caution
in the application of models outside of the region for which they were developed. 相似文献
9.
Abstract: The effectiveness of rare plant conservation will increase when life history, demographic, and genetic data are considered simultaneously. Inbreeding depression is a widely recognized genetic concern in rare plant conservation, and the mixing of genetically diverse populations in restoration efforts is a common remedy. Nevertheless, if populations with unrecognized intraspecific chromosome variation are crossed, progeny fitness losses will range from partial to complete sterility, and reintroductions and population augmentation of rare plants may fail. To assess the current state of cytological knowledge of threatened and endangered plants in the continental United States, we searched available resources for chromosome counts. We also reviewed recovery plans to discern whether recovery criteria potentially place listed species at risk by requiring reintroductions or population augmentation in the absence of cytological information. Over half the plants lacked a chromosome count, and when a taxon did have a count it generally originated from a sampling intensity too limited to detect intraspecific chromosome variation. Despite limited past cytological sampling, we found 11 plants with documented intraspecific cytological variation, while 8 others were ambiguous for intraspecific chromosome variation. Nevertheless, only one recovery plan addressed the chromosome differences. Inadequate within‐species cytological characterization, incomplete sampling among listed taxa, and the prevalence of interspecific and intraspecific chromosome variation in listed genera, suggests that other rare plants are likely to have intraspecific chromosome variation. Nearly 90% of all recovery plans called for reintroductions or population augmentation as part of recovery criteria despite the dearth of cytological knowledge. We recommend screening rare plants for intraspecific chromosome variation before reintroductions or population augmentation projects are undertaken to safeguard against inadvertent mixtures of incompatible cytotypes. 相似文献
10.
WALTER SMITH 《Natural resources forum》1977,1(3):203-213
Land information is a basic tool for nearly all development effort, yet much available information is not used because decision-makers are unaware of its existence. To improve its utilization, the base for storage and presentation of land information, covering all user needs, should be a national map/national co-ordinate system. By this means the inter-relationship of various types of information can be appreciated and their value correspondingly increased. 相似文献