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Information on the amount of vertebrate prey caught by house cats in Canberra
was collected by recording prey deposited at cat owners' residences over
12 months. The amount of prey taken was not significantly influenced by cat
gender, age when neutered, or cat breed. Nor did belling or the number of
meals provided per day have a significant influence on the amount of prey
caught. The age of the cat and the proportion of nights spent outside
explained approximately 11% of the variation in the amount of prey
caught by individual cats. In all, 43% of variation in predation on
introduced species (predominantly rodents) was explained by distance from
potential prey source areas (i.e. rural/grassland habitat) and cat
density. The mean number of prey reported per cat over 12 months (10.2) was
significantly lower than mean predation per cat per year based on estimates
made by cat owners before the prey survey began (23.3). Counts of the amount
of prey caught by house cats were highly positively skewed. In all, 70%
of cats were observed to catch less than 10 prey over 12 months, but for
6% of cats, more than 50 prey were recorded. Estimates of predation by
house cats, particularly extrapolated estimates, should be treated with
caution. The total number of prey caught by house cats in Canberra estimated
using the sample median was approximately half the estimate based on the
sample mean. Predation estimates alone do not prove that prey populations are
detrimentally affected, especially in highly disturbed and modified
environments such as suburbs. Impacts on native fauna are likely to be most
significant in undisturbed habitat adjacent to new residential developments.

Studies of predation by house cats in Australia have not attempted to compare
the composition of prey taken by cats with the relative availability of prey.
Information on the composition of vertebrate prey caught by house cats in
Canberra was collected by recording prey deposited at cat owners'
residences over 12 months. A total of 1961 prey representing 67 species were
collected or reported. In all, 64% of prey were introduced mammals,
especially mice and rats, with birds comprising 27% (14% native,
10% introduced, 3% unidentified), reptiles 7%, amphibians
1% and native mammals 1%. Predatory behaviour by house cats
appeared largely opportunistic with respect to spatial (habitat) and temporal
(daily and seasonal) prey availability and accessibility, although there is
mounting evidence from this and other studies that small mammals are the
preferred prey. While this means that introduced mice and rats are common prey
of house cats in urban and suburban environments, it also suggests that in
relatively undisturbed environments adjoining new residential developments,
predation by house cats may have a substantial impact on locally abundant,
patchily distributed populations of native fauna, particularly mammals.
Imposing night-time curfews on cats is likely to lessen predation of mammals
but will probably not greatly reduce predation of birds or reptiles.

In October, 1985, discussions were held in Santiago in regard to the possibility of organizing a minerals industry conference in Chile in November, 1986, under the auspices of the Institution of Mining and Metallurgy and in association with other bodies and organizations. I, in turn, was asked to chair the Organizing Committee and at our first meeting in London in November, 1985, we realized how little time we had if we were to meet the date proposed. In the event, thanks to considerable support from the Organizing Committee and others, coupled with the very good response from authors, we were able to put together a programme on a variety of topics, with some particular emphasis on operations in South America, and with special reference to Chile, that we regard as attractive. This is the first conference to have been organized by the Institution of Mining and Metallurgy in Chile, but it is intended that it should initiate a series to be held in Latin American countries. Chile has a long and healthy mining tradition and it is fitting, therefore, that it should have been chosen for the first such conference.

Hydropower -- Lesotho Highlands Water Project: design and layout of underground works for 'Muela Hydropower Project -- Design and construction of the cooling water intake tunnel system for Point Aconi generating station, Nova Scotia -- Comparison of two classification systems as applied to the Alpe Devero tunnel, Italy -- Metro/Rail -- Planning and design of tunnels for the Jubilee Line extension, London -- New St Clair River tunnel, Canada-USA -- Application of NATM to design of underground stations in London Clay -- Water/Waste -- Underground works on Third Nairobi Water Supply Project -- Design and construction of caverns for an underground sewage treatment plant, Hong Kong -- The Snake: a rock tunnel for storing combined sewage water, Stockholm -- Tunnelling on the Penzance and St. Ives sewerage scheme, Cornwall, England -- Tunnel-boring Machines -- Two tunnel-boring machines for Lesotho: a design and case history -- Open TBM tunnelling in complex geology for railroad in Sweden -- Use of sedimentary rock impact indices in evaluation of tunnel-boring machine performance -- Development and performance of tunnel-boring machines on Phase II of the London Water Ring Main -- Environmental Issues -- Environmental planning for the Massachusetts Water Resources Authority's MetroWest water supply tunnel -- Palais Bernheimer in Munich: tunnelling for parking space under a historic building -- Limiting the damage to historic buildings due to tunnelling: experience at the Mansion House, London -- Compensation grouting to limit settlements during tunnelling at Waterloo Station, London -- Ground movement model validation at the Heathrow Express trial tunnel -- Case Histories -- Gjøvik Olympic Mountain Hall, Norway -- Construction of new escalator shaft and passageways at London Underground's Waterloo Station -- Water in TBM drives, Delivery Tunnel South, Lesotho Highlands Water Project -- Tunnel-boring Machines -- CEN safety standards for tunnelling machines and air locks -- Tunnels below waste disposal tips -- Machine tunnelling in the northwest of England -- EPB-shield tunnelling for the Taipei Metro, contract 201A -- TBM drive management by use of computerized systems -- Research -- Long-term measurements of loads on tunnel linings in overconsolidated clay -- Non-destructive investigation of tunnels -- Case Histories -- Design, construction and performance of a 700-m 'cover and cut' tunnel in soft clay, Norway -- Shotcrete in the construction of Pen-Y-Clip tunnel, North Wales -- Face support for a large Mix-Shield in heterogeneous ground conditions -- Design -- Tunnel ring design, development, testing and manufacture for the London Water Ring Main -- Medway tunnel detailed design -- Developments in precast concrete tunnel linings in the United Kingdom -- Case Histories -- Channel tunnel: French undersea crossover design and construction -- Design and construction of Metsovon road tunnel, Greece -- Construction of the 'Passante Ferroviario' link in Milan, Italy, lots 3P, 5P and 6P: excavation by large earth pressure balanced shield with chemical foam injection -- Pen-Y-Clip road tunnel, North Wales: achieving a dry lining through a pervious rock formation -- Hydropower -- Tunnel design in the design and construct context—the Pergau experience, Malaysia -- Serra da Mesa project, Brazil: excavation of shafts and penstocks -- Tunnel Machinery -- Rock cutting with roadheaders -- Increased productivity in construction of civil and mining tunnels through the use of high-capacity tunnel-boring machines and continuous belt conveyor muck haulage.