Artificial lighting is a particular problem for animals active at night. Approximately 69% of mammal species are nocturnal, and one-third of these are bats. Due to their extensive movements—both on a nightly basis to exploit ephemeral food supplies, and during migration between roosts—bats have an unusually high probability of encountering artificial light in the landscape. This paper reviews the impacts of lighting on bats and their prey, exploring the direct and indirect consequences of lighting intensity and spectral composition. In addition, new data from large-scale surveys involving more than 265 000 bat calls at more than 600 locations in two countries are presented, showing that prevalent street-lighting types are not generally linked with increased activity of common and widespread bat species. Such bats, which are important to ecosystem function, are generally considered ‘light-attracted’ and likely to benefit from the insect congregations that form at lights. Leisler's bat ( Nyctalus leisleri ) may be an exception, being more frequent in lit than dark transects. For common pipistrelle bats ( Pipistrellus pipistrellus ), lighting is negatively associated with their distribution on a landscape scale, but there may be local increases in habitats with good tree cover. Research is now needed on the impacts of sky glow and glare for bat navigation, and to explore the implications of lighting for habitat matrix permeability.

A robust and cost-efficient method for monitoring some of Ireland's more common bat species was devised in 2003 and has been carried out yearly since then. The objective of the scheme is to provide information on bat population trends and distributions in Ireland. Night-time surveys are conducted in July and August, whereby bat vocalizations are recorded from a time expansion bat detector to a minidisc while driving a known route by car at a constant driving speed. Bat vocalizations are subsequently analysed using sound analysis software. In Ireland, the roadside populations of three target species, the common pipistrelle, soprano pipistrelle and Leisler's bat, can be monitored effectively using this car-based method of survey. Power statistics indicate that a decline of high conservation priority of the least frequently encountered species of the three, Leisler's bat, could be detected within 12 years of monitoring if 25, 30 Â 30 km survey squares, each with fifteen 1.6 km transects, are surveyed twice annually. The scheme has revealed new data on the relative bat activity distributions across the island of Ireland. Common pipistrelles are more frequent in the south of the country and Leisler's bats are more frequent in the south and east. Analysis of yearly count data indicated an initially increasing trend in the common pipistrelle and Leisler's bat for the first 4 years of the survey, followed by more recent declines. Ireland has a relatively depauperate bat fauna; hence, a potentially greater number of microchiropteran species could be monitored in other regions using this method. The protocol is easily repeatable and does not have to be carried out by bat specialists. In Ireland, it takes c. 300 h of volunteer time annually to carry out this statistically robust monitoring scheme for all three bat species.

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Novel real-time PCR species identification assays for British and Irish bats and their application to a non-invasive survey of bat roosts in Ireland,

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