25,471 research outputs found
Estimating bird abundance : making methods work
No full textIn many bird monitoring Surveys, no attempt is made to estimate bird densities or abundance. instead, counts of one form or another are made, and these are assumed to correlate with bird density. Unless complete Counts Oil Sample plots are feasible, this approach can easily lead to false conclusions, because detectability of birds varies by species, habitat, observer and many other factors. Trends in time of counts often reflect trends in detectability, rather than trends in abundance. Conclusions are further compromised when surveys are conducted at unrepresentative sites. We consider how to avoid these problems. We give a brief description of distance sampling methods, which allow detectability to be estimated. We consider strategies to ease their implementation, to enhance their reliability, to adapt the methods for difficult species, and to deal with circumstances in which representative sampling is problematic. We also consider some of the common problems encountered, and suggest solutions.Peer reviewe
Bird species richness and diversity at montane Important Bird Area (IBA) sites in south-eastern Nigeria
No full textThe mountains of south-eastern Nigeria are a western extension of the Cameroon mountain range, which is classified as an endemic bird area (EBA). Unlike its eastern extension in Cameroon, most of the ornithological surveys in the western extension of the Cameroon highlands in Nigeria have produced only limited checklists and inventories. There is a clear need for quantitative baseline data so that conservation problems can be identified. Twenty line transects covering a total transect length of 28.8 km were used to survey five sites (Afi Mountain Wildlife Sanctuary, Oban and Okwangwo Division of Cross River National Park, Sankwala Mountains and Mbe Mountains) in the westernmost extension of the Cameroon Mountains EBA in south western Nigeria. Vegetation measurements were taken to control for the potential confounding effect of variation in vegetation density and structure on detectability of birds between sites. The 193 bird species recorded in Afi, 158 in Sankwala, 124 in Oban, 100 in Mbe and 73 in Okwangwo Division included most of the Cameroon highlands restricted range species. The results show that the mountains of south-eastern Nigeria are important parts of the Cameroon EBA, particularly the Afi Mountain Wildlife Sanctuary. However these sites are threatened by fire and livestock grazing on the hilltops, shifting agriculture on the hillsides and lowlands, and logging for timber in some parts, as well as wildlife hunting for bush meat.Peer reviewe
Relationships between hedgerow characteristics and bird communities:: a multivariate approach
No full textFifty 100m hedge transects were selected within 10km of Durham City, North England. The bird community of the hedge transects was censused six times between May and July, and characteristics of the hedge and surrounding landscape were recorded. The data was analysed using multivariate methods to determine the importance of the microstructure of the hedge in relation to aspects of the bird community. Stepwise Multiple Regression selected the scores of the first axis of a Detrended Correspondance Analysis of shrub abundance data (related to the height and width of the hedge) as the best predictor of Bird species richness and density. Individual species were related to different aspects of the hedge microstructure. The use of transformed independent data improved the predictive value of most of these relationships. A Detrended Correspondance Analysis found that major source of variation in the bird species abundances was due to the number of trees in the hedge. Canonical Correspondance Analysis was used to analyse how a community responds to a set of external factors. The CANOCO first axis was related to an increase in the area of nearby woodland in the positive end and an increase in the number of trees in the negative end. The position of the species scores in relation to these environmental gradients was analysed. The habitat preferences of 4 common species of bird was explored using "sector” analysis, whereby the mean density of the species is plotted against the major sources of variation in the environmental variables, different habitat preferences between species are apparent. The importance of trees to the bird community was elucidated using Linear Discriminant Analysis. The analysis was carried out with hedges with no trees and hedges with 3 or more trees as the two a priori groups. Eighty-three percent of the sites were placed in the correct groups, using 14 common bird species as variables. The importance of the microstructure of the hedge to the bird community is discussed
Cooperation bibliogram of bird flu
No full textThe published literature on Bird Flu, now a pandemic animal disease with a possible potential of evolving into a devastating human disease, was analysed primarily with respect of national and international cooperations and networks of authors and countries. The output of research-relevant papers is now around 150 per year and was less than 100 papers per year before 2003. The field is highly cooperative; nearly 90% of the articles have two or more authors. National extramural cooperation is around 50% since 1998, intramural cooperation shows a decreasing tendency and is now about 20%. Between 20% and 30% of the papers have been published in bi- or multinational cooperation. Observed and expected citation rates of international papers are twice as high as the citation rates of national papers.
47 countries are engaged in Bird Flu research, on top USA, followed by PEOPLES R CHINA, UK and JAPAN. These countries are also centers of country networks, but minor centers exist. An Asian local network with strong ties consisting of countries most affected by Bird Flu can be identified.. No strong direct connections exist between Europe and Asia; thus it seems necessary to intensify international cooperation.
Author network show interesting cluster structures which must be studied in detail
The design and construction of a flying bird robot
No full textThe purpose of this project is to investigate the issues surrounding the design and construction of a flying bird robot. The ideal would be to re-create a model of a bird that looks like bird, functions like a bird with regard to the biomechanical issues involved in flight and uses control systems that emulate the ones used by the bird to control the flight path
Bird communities and vegetation on Swedish wet meadows
No full textWet meadows in Sweden currently depend on management by grazing to maintain habitats for various breeding and migrating birds. However, due to ceased cattle farming management by mowing could be an option for restoration and conservation of wet meadows. The general aim of this thesis is to analyse effects of different management regimes (mowing and grazing), landscape composition and flooding on inland wet meadow bird fauna and flora. Five wet meadow areas in southern Sweden were used for a four-year survey of breeding birds and environmental variables. Habitat openness was the most important factor for bird community composition. Species preferring open meadows decreased strongly in abundance at small amounts of forest, suggesting that clearing of woodlands could be important. The bird community was also strongly related to the amount of flooding. Effects of management were weaker, but several species showed positive associations with swards of intermediate height (5-30 cm), which are correlated to mowing with late season grazing. In addition, measures for restoring water table variation also need to be considered. Conservation of species dependent on continuous management (yearly grazing, mowing and late season grazing) and short swards should be targeted to large open meadows. Corncrakes preferred unmanaged meadows with tall vegetation, suggesting that mowing at intervals of a few years could be appropriate. Yellow Wagtails are likely to have higher breeding success in mowed than in grazed sites due to lack of nest destruction by livestock. The main gradients affecting distribution of vascular plants correlated to soil fertility and moist. Bird species associated with weak or no management correlated positively to nutrient levels, soil reaction, sward height and litter depth. In contrast, the assembly of bird species associated with continuous management, showed fewer associations to the sward variables, although their abundance was positively associated with abundance of forbs. Different mowing regimes may be a useful tool for management of meadow sward heterogeneity
Evaluating the Effects of a Bird Strike Advisory System
No full textBird strikes have operational impacts and cause economic loss to the aviation industry. In the worst case, the damages resulting from bird strikes lead to crashes. The highest risk for bird strikes is in the area below 3000 ft and thus mainly in airport environments. Despite intense efforts from the airports in controlling the local bird populations, the number of bird strikes in these environments is still very high. Usually, Air Traffic Control is neither integrated into the process for reducing bird strikes nor do the controllers receive any precise information about the current bird traffic situation at the airport. For the project described in this paper, we assume a different situation: Air Traffic Control is provided with a tool informing the controller about the current and predicted bird traffic at the airport. Based on this information, the controller can decide to delay departing air traffic in order to avoid potential collisions between birds and the aircraft taking off. When implementing this procedure at an airport, we expect an increase in airport safety and, due to the delaying of traffic, a reduction in runway capacity. We hypothesize, that the Relations between the settings of the alerting systems and the effects on safety and capacity are deterministic. To test this hypothesis, we will perform
fast-time simulations under varying conditions. This paper describes the simulation environment created for this purpose
Oak bird guide
No full textTitle from PDF cover (viewed on February 28, 2017).This archived document is maintained by the Oregon State Library as part of the Oregon Documents Depository Program. It is for informational purposes and may not be suitable for legal purposes.Includes bibliographical references (page 26-28).Funding for this document was provided by the U.S. Fish and Wildlife Service through the Neotropical Migratory Migratory Bird Conservation Act.Mode of access: Internet from the Oregon Government Publications Collection.Text in English
Plan of XXX [30] allotments Balmain Darling Harbour [cartographic material] /
No full textMap of Balmain area between Ferry Road and Darling Harbour showing proposed wharf, cottages, fences and offices with adjoining landholders.; Also available in an electronic version via the Internet at: http://nla.gov.au/nla.map-f538; Ferguson Collection Map F 538
Plan of choice allotments situate at Balmain [cartographic material] /
No full text"Sketch of Location"; Map of allotments for sale at Balmain at corner of Birch Grove Road and Darling Road.; Published after the opening of Mort's Dock in 1855 nd and before Bird's change of address by 1858.; Also available in an electronic version via the Internet at: http://nla.gov.au/nla.map-f533; Ferguson Collection Map F 533
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