BCT’s Position Statement on the Proposed Norwich Distributor Road Western Link

BCT’s Position Statement on the Proposed Norwich Distributor Road Western Link

Date: 04 March 2021


This position statement sets out the Bat Conservation Trust’s (BCT’s) position on the proposed Norwich Distributor Road (NDR) Western Link. This is a proposed extension to the NDR, construction of which was completed in 2018.

Wild Wings Ecology have reported that survey work carried out by them in 2019 and 2020 has resulted in the discovery of a large, nationally significant population of bats of the species barbastelle (Barbastella barbastellus) along the proposed road route. Within this is the largest known UK roost for barbastelle, supporting 105 individuals within one tree, and it is reported that the whole population consists of 270 individuals with maternity roosts spread through several woodlands in the area (Packman, 2020). The nationally important status of the colony and the threat to this is the reason for BCT producing this position statement.

Legal protection for bats

All of the UK’s bat species are legally protected from killing / harm, disturbance, and obstruction / destruction of their roosting habitat by the Conservation of Habitats and Species Regulations 2017 and the Wildlife and Countryside Act 1981 (as amended). This legal protection was put in place as a result of historic declines and some bat species are showing early signs of recovery.

Status of barbastelle

However, the barbastelle is particularly rare and thought to still be declining throughout its range across Europe. Barbastelle is listed as ‘Near Threatened’ on the Global IUCN Red List and ‘Vulnerable’ on the UK Red List, which also describes it as ‘at imminent risk of extinction’ and estimates a population of 4500 individuals in England. It is offered special protection through its listing on Annex II of the Habitats Directive, requiring for member states to designate Special Areas of Conservation (SAC) to protect the species and its habitats.

Potential impacts of major road schemes

The potential impacts of road schemes on bats include destruction, degradation and fragmentation of roosting, foraging and commuting habitat; mortality of bats through collision with vehicles and disturbance from noise and lighting associated with the road.

The impact of roads on bats was studied by Berthinussen and Altringham (2012a), who reported that bat activity and diversity reduced with increasing proximity to a major UK road, probably due to habitat degradation (through noise, light and chemical pollution), the barrier effect and/or road mortality. Finch et al. (2020) report that both bat activity and feeding behaviour are negatively affected by traffic noise playback.

Mitigation and compensation methods available

Attempts to mitigate and compensate for the impacts of road schemes on bats generally include the provision of alternative roosting habitat (for example, using bat boxes or veteranisation of trees), planting of new commuting and foraging habitat, the provision of crossing points for bats to cross the road safely and sensitive lighting schemes.

Limitations of these methods

It is clear that new planting cannot replace mature woodland and the roosting and foraging opportunities it offers to mature woodland specialists such as the barbastelle. Indeed, it will take many years for any such new planting to provide those needs. Too long to support current colonies of bats impacted by the scheme.

Berthinussen and Altringham (2012b) reported on the efficacy of road crossing points for bats, concluding that bat gantries are ineffective but underpasses do have potential (if they are of sufficient size and placed along pre-construction commuting routes) and green bridges warrant further research into their efficacy.

Fensome and Mathews (2016) analysed evidence on road mortality for bats from across Europe and found that juveniles are more prone to collision (making maternity colonies close to roads particularly vulnerable) and that rare species such as barbastelle have been discovered as casualties on the roads studied.

Impacts from light pollution are often addressed by sensitive lighting schemes but this does not reduce the negative impact of vehicle headlights. Impacts from noise and chemical pollution are often not addressed and we are not familiar with any mitigation measures that have been both proposed and tested for their efficacy.

Local Planning Authority duty

This barbastelle population is of national significance because of the number of bats it supports. Whilst the site is not yet designated as a Special Area of Conservation (SAC) it does qualify and should not need to be designated to be protected.

A SAC site threatened by impacts from development would be subject to a Habitats Regulations Assessment. Where an adverse impact on the integrity of a SAC is predicted and no alternatives are available permission can only be granted if there are imperative reasons of over-riding public interest and if appropriate compensatory measures are available and applied.

Regardless of SAC status, the National Planning Policy Framework (2019) states that:

  • Planning policies and decisions should contribute to and enhance the natural and local environment by: a) protecting and enhancing valued landscapes, sites of biodiversity or geological value and soils (in a manner commensurate with their statutory status or identified quality in the development plan); and
  • · When determining planning applications, local planning authorities should apply the following principles: a) if significant harm to biodiversity resulting from a development cannot be avoided (through locating on an alternative site with less harmful impacts), adequately mitigated, or, as a last resort, compensated for, then planning permission should be refused.

The available evidence suggests that the impacts of the proposed NDR Western Link on this nationally significant barbastelle population cannot be adequately mitigated or compensated for and we have significant concerns about this scheme if taken forwards as proposed.


Berthinussen, A. & Altringham, J. (2012a) The effect of a major road on bat activity and diversity. Journal of Applied Ecology, 49, 82-89. Found here: The effect of a major road on bat activity and diversity on JSTOR

Berthinussen, A. & Altringham, J. (2012b) Do Bat Gantries and Underpasses Help Bats Cross Roads Safely? PLoS ONE 7(6): e38775. Found here: Do Bat Gantries and Underpasses Help Bats Cross Roads Safely? (plos.org)

Fensome, A. and Mathews, F. (2016) Roads and bats: A meta-analysis and review of the evidence on vehicle collisions and barrier effects. Mammal Review 46(4). Found here: Roads and bats: a meta‐analysis and review of the evidence on vehicle collisions and barrier effects - Fensome - 2016 - Mammal Review - Wiley Online Library

Finch, D., Schofield, H. & Mathews, F. (2020) Traffic noise playback reduces the activity and feeding behaviour of free-living bats.

Environmental Pollution,Volume 263, Part B. Found here: Traffic noise playback reduces the activity and feeding behaviour of free-living bats - ScienceDirect

Packman, C. (2020) Norfolk’s Nature Discovery of the Year webinar 08.12.20. Found here: Norfolk's Nature Discovery of the Year webinar 08.12.20 - Dr Charlotte Packman's talk - YouTube