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Improving mitigation success where bats occupy houses and historic buildings, particularly churches. - WM0322

As European Protected Species, bats are strictly protected under European and United Kingdom legislation because of concerns about their conservation status. Current legislation (Conservation of Habitats and Species Regulations 2010) protects all bat roosts from destruction, damage or disturbance, whether occupied or not. This legislation also places a duty on all competent authorities (including churches), to take bats into account adequately when works such as building restoration have the potential to damage roosts or disturb bats. At times conflicts can arise between humans and bats, especially in houses and churches. Defra authorises Natural England to grant licenses for management and mitigation activities that can reduce potential conflicts between people affected adversely by the effects of bats in buildings, and the necessity to maintain the favourable conservation status of the species. The aim of this research is to improve mitigation success where bats occupy houses and historic buildings, especially churches.

Two areas where conflict can be substantial are (i) when large maternity roosts of bats occur in dwellings, and house owners or tenants are affected severely by their presence (e.g. by phobias) and (ii) in churches, where for example bat droppings and urine might damage artefacts of historic and cultural significance. One assumption of current legislation is that licensed activities will not be detrimental to the maintenance of the population of the species concerned at a favourable conservation status in their natural range. In exceptional circumstances exclusion of bats can be licensed, but the fate of the excluded bats and any impacts on their favourable conservation status remain unknown.

One component of this study is to determine whether bats excluded from buildings are able to find alternative roosts. We will use radio-tracking of soprano pipistrelle bats prior to and after exclusions to determine whether the bats find alternative roosts successfully, and whether their foraging sites shift after exclusion. Comparisons of colony growth estimates due to fledging of youngsters at control (non-excluded) sites in the same area will allow quantification of whether the breeding success of excluded colonies is reduced. By building models that include local population density and a range of negative impacts on reproductive success that might arise from exclusions, we will predict impacts on local populations.

Parish churches are treasured and enduring features of the English landscape. Approximately 60% of pre-16th Century churches are estimated to contain bat roosts, and some have provided valuable roosting sites for many generations of bats. Natterer's bats sometimes form large maternity colonies in churches, and cause problems for church authorities especially in East Anglia. We will design experiments to attempt relocating bats away from problem areas in churches. Our approach will involve the provision of alternative roosting areas both within and outside of churches. We will determine the use of alternative roosts by using radio-tracking and we will monitor roost micro-climates by placing temperature loggers at roosting sites. We will perform a literature review, and seek advice from a project steering panel and from focus groups to determine the best systems for both attracting bats to new sites and deterring them from existing ones. We will consider the use of light, ultrasound and radar as possible deterrents, and use one of these (determined after pilot studies) in a replicated experiment to determine whether it is possible to encourage bats to use new roosting areas.

We will determine patterns of habitat selection by Natterer's bats that roost in churches, and determine whether patterns of selection alter when bats move roosts. We will quantify habitat quality around churches used as roosts by using Geographic Information Systems, and will determine whether churches used by roosts contain more of the habitats preferred by radio-tracked bats than do churches not used as roosts. As a consequence of our evidence-based research, we will develop an advisory leaflet with English Nature and other interested organisations outlining the costs and benefits of different management options for reducing conflicts between humans and bats in buildings.
Project Documents
• FRP - Final Report : WM0322 Final Report   (3935k)
Time-Scale and Cost
From: 2012

To: 2014

Cost: £602,029
Contractor / Funded Organisations
University - Bristol
Environmental Protection              
Nature conservation              
Wildlife conservation              
Fields of Study
Wildlife Management