ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1990.tb01034.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Effective wildlife monitoring schemes identify changes in population variables that require conservation action. This must be based on an understanding of normal patterns of population variability. Monitoring schemes ideally provide data on the stages of the life cycle at which changes are taking place and indications of the probable causes of change.The Integrated Population Monitoring Programme of the British Trust for Ornithology aims to fulfil these requirements for British birds. It encompasses existing BTO projects that measure population size, productivity and survival rates, principally the Common Birds Census, Waterways Bird Survey, Nest Record Scheme, Constant Effort (mist‐netting) Sites Scheme and the Ringing Scheme. Integrated analyses of long‐term BTO data are being used to study the population dynamics of individual species. Relationships established through such analyses will be used to construct models that will predict population performance, and against which observed performance can be compared.A simple application of Integrated Population Monitoring is presented using data for the Song Thrush (Turdus philomelos), a species which has been declining throughout most of Britain since the mid 1970s. No reduction in reproductive performance was detected and the decline appears to have been brought about through reduced survival rates. Factors responsible for much of this decline were identified from a multiple regression model involving winter weather conditi

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1990.tb01035.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Although fewer than one‐fifth of the world's bird species are restricted to islands, over 90% of bird extinctions during historic times have occurred on islands. The major identified cause has been the effects of exotic animal species introduced by man; the largest number of documented extinctions has occurred on islands of the Pacific Ocean.Some 39% (402) of threatened bird species are restricted to islands and more than 907; of these are endemic to a single geopolitical unit. The largest numbers occurring in such units are in Indonesia (91) and the Philippines (34). As a region, the Pacific holds more threatened species (110) than any other, including almost half of those considered Endangered and over 40% of the Vulnerable species.Most threatened island species are forest‐dwelling. A high proportion of the Endangered species use seasonal/temperate forest. While habitat destruction now poses the greatest overall threat to island birds (affecting over half the species restricted to islands), the presence of introduced species threatens 30 of the 66 Endangered species.Although immediate extinctions of island species can best be averted by mitigating the effects of introductions, the removal of native forests will be a more severe problem in the longer term. There is an urgent need for ecologists to provide detailed information on the habitats of both threatened and endemic species so that more appropriate and effective conservation programmes can be develo

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1990.tb01036.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Birds may harbour many organisms, some of which can be transmitted to humans (zoonoses) and domestic livestock. Certain zoonoses are of considerable importance and their control may necessitate changes in management of bird populations. If problems relating to zoonoses are to be effectively tackled there is a need for closer collaboration between ornithologists and those concerned with public health, more research on avian diseases and the collation of relevant data.

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1990.tb01037.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

The hazard presented to birds by the use of a particular pesticide is dependent on many factors and may therefore vary in its severity. Even effects which occur very infrequently may sometimes be sufficiently severe to warrant regulatory action. The potential for variability is illustrated by the effects of carbophenothion on geese and of fenitrothion on forest songbirds. Potential for the movements and behaviour of birds to vary their exposure to pesticides is illustrated using data on Tree SparrowsPasser montanusand Brent GeeseBranta bernicla. Methods used in the assessment of pesticide effects are reviewed, and their ability to cope with variability is discussed. Further research is required to extend understanding of the mechanisms which cause variability, and to assess the sensitivity of methods for monitoring the effects of pesticides during commercial use.

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1990.tb01038.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Shetland holds a very high concentration of seabirds that feed to a large extent on sandeelsAmmodytes marinus. The available data allow an assessment of the quantity of sandeels consumed by seabirds each year 1981–83, and sensitivity analysis suggests that this figure is accurate to about ±30%. Only very approximate estimates of sandeel consumption by seals and by predatory fish can be made.From 1981 to 1983 the Shetland fishery catch averaged 45,000 tonnes of sandeels, with an estimated natural consumption of 47,000 tonnes by seabirds (predominantly GuillemotsUria aalgeand FulmarsFulmarus glacialis). Based on sensible guesses and the little data available, consumption may have been about 25,000 tonnes by predatory fish and 9,000 tonnes by seals. The figures suggest that natural mortality of the Shetland sandeel stock in 1981–83 was considerably in excess of the figure used in VPA stock assessments. Further information is required for key variables in order to permit better estimates of sandeel stock dynamics. In particular, we need better data on numbers and diets of seals in Shetland, numbers and diets of predatory fish, diets and foraging distributions of Fulmars, especially out with the chick‐rearing period. In future, sandeel biomass assessments for Shetland should incorporate estimates of predation by seabirds as this is clearly an important part of total mortality for the

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1990.tb01039.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Habitat selection by LapwingsVanellus vanellusvaries seasonally, with aerodromes comprising a preferred habitat in late summer and again in late autumn and winter. The presence of flocks of Lapwings on aerodromes poses a flight safety problem but management of the aerodrome habitat, especially the grass areas, combined with scaring, can minimize the hazard. The consequences of displacing large numbers of Lapwings from aerodromes to other habitats are reviewed in relation to the declines in breeding populations that have occurred as a result of changes in agricultural practices.

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1990.tb01040.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Recent studies on the migrations of the Red‐billed QueleaQuelea queleahave shown that while the species is capable of long‐distance movements of hundreds of kilometres, the actual migrations probably more often consist of shorter distances with a flexible timing. This flexibility allows adjustments to be made to the rainfall distribution in a particular year. New information comes from studies on the breeding distribution, on the plumage and moult of local populations, and from attempts to apply new techniques such as mass‐marking with fluorescent particles. Breeding has been shown to be both more widespread and more frequent than previously recognized, while local populations can prolong breeding in one place if rainfall continues. Local populations have been identified that are apparently distinct, with limited intermixing with other populations, and some data suggest that intermixing may be reduced by flock or group cohesion. The flexibility of the migrations means that predictions of major influxes of quelea into agricultural areas have proved difficult to make, especially in regions where the rainfall patterns are complex and variable, such as East A

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1990.tb01041.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Changes in legislation, in public attitudes and in shooting practices, both in Britain and overseas, have allowed populations of geese which winter in Britain to increase in numbers. Since 1960 the number of individuals in the seven populations that come into conflict with agriculture has increased almost fivefold.There are serious conflicts between geese and farmers in some localities, where damage is alleged to growing grass, cereals and high value cash crops. Despite extensive studies over 20 years, it has proved impossible to devise precise and cost‐effective methods of assessing the damage caused by geese and to provide a fair and workable system of compensationFarmers and their representatives are calling for a co‐ordinated cull to reduce population sizes substantially. There are, however, a number of political and practical problems in undertaking population control, except perhaps in the feral populations of GreylagAnser anserand Canada GeeseBranta canadensisin England.Proposals are put forward for each species, which take into account the international responsibility of each country to safeguard the populations of migratory birds, and which provide solutions to the local serious problems of farmers. These proposals involve the setting aside of land for geese, either by the creation and management of reserve areas or by making payments to farmers to tolerate the birds on their l

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1990.tb01042.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

In The Netherlands farmers can apply to the Game Fund in order to receive compensatory payments in the event of damage by wild mammals and birds. In recent years the amount of money paid annually has increased up to £758,000. Although adequate as a basic measure to offset the losses suffered, the large increase in the total amount involved leads to questions about the accuracy of the estimated damage in relation to the actual crop reduction.In certain areas in The Netherlands research is aimed at minimizing damage by altering land use in agricultural areas and restoring original habitats for wintering geese. This is a new approach for solving the apparent future conflict between a further increase of the amount of money paid to refund the damage claimed and the aims of conservation

ISSN:0019-1019    

DOI:10.1111/j.1474-919X.1990.tb01043.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY