Norfolk County Council faces a major dilemma with its current plans to build a dual-carriageway link road around the north-western outskirts of Norwich. The council claims that the new route would hugely reduce carbon emissions in the local area over future years and that the economic case for the road is sound, despite the additional cost of mitigation measures including green bridges. It also maintains that building the road would be better for the environment than not building it.
However, recent ecological surveys have uncovered a very significant colony of Barbastelle bats living in the mature, river-valley woodlands through which the road would pass. Within Britain, these bats only live in the southern counties of England and Wales, whilst the only other colonies worldwide are found in central Europe and southern Scandinavia. Opponents now believe that to continue with the current road development plans would, amongst other things, destroy this important colony of rare bats. Of course, such destruction would seemingly contradict the recently declared aim of reversing the UK’s decline in biodiversity by 2030, as required by the UK Environment Act 2021 which became law barely a month ago, and potentially add further to the woeful record that the UK has for preserving biodiversity.
Studies of the Norwich bat colony since 2020, by Dr Charlotte Packman, have revealed that the woodlands along the proposed route support more than 270 Barbastelle bats, making this group a significant part of the UK’s total population. Not only would the road destroy many of the mature trees that this bat relies on for its roosts and sources of food (principally moths), but it would provide significant hazards to any bats, who can find homes and food in the remaining patches, when they cross the road during foraging and commuting flights. The road traffic would also increase chemical and noise pollution, as well as night-time light levels, all of which have been shown to disrupt breeding Barbastelle colonies.
Although the ecological damage done by many development projects can be offset by appropriate mitigation measures, it does not seem possible in this case to employ any suitable mitigations in the near future, or before the woodland habitat and its bat roosts have been decimated. Barbastelle bats require the habitats only provided within mature, deciduous-woodland river valleys, incorporating a wide variety of tree types and ages. The development of suitable replacement “homes” would therefore take many tens of years to achieve, even if appropriate valley locations could be planted, with some trees “veteranised” to create potential roost locations. Even if suitable replacement homes could be provided, could these notoriously sedentary bats then be persuaded to move?
Furthermore, bat gantries, which have been installed within other road-building schemes, to guide bats across busy roads above traffic height thus reducing collisions, have been shown to be ineffective. Unfortunately too, the “jury is still out” on alternative road-crossing protection schemes, although well-positioned underpasses of sufficient size are thought to merit further study, whilst green bridges are thought to require long periods after construction, to allow sufficient vegetation to grow, to be of any real benefit.
Moreover, it is hard to imagine how the noise and chemical pollution hazards presented by thousands of vehicles using the road throughout the day and night could be mitigated. Similarly, although careful positioning of suitable street lights might minimise the impact of night-time light levels on any remaining colony locations, the “pollution” provided by vehicle headlights will be almost impossible to mitigate. Of principal concern though is that if the bat colony has been decimated by the loss of trees, the installation of costly mitigation measures like these would be of little value.
It appears that protests over, and opposition to, the potential destruction of the woodland habitat have also led to reduced support from local businesses. Let’s therefore hope that the council and other interested parties can develop suitable alternative plans for roads around Norwich, so that this colony of rare bats can continue to thrive, and all interested parties achieve a win-win outcome.
JP Ecological Services 