Contrary to popular belief the peak bat survey season is at the same time every year, May to August. The season doesn’t move around making it difficult to locate or hide to ensure that people miss it. So why is it then that every year at the beginning of September there is a rush of people wanting to ‘squeeze in their bat surveys before the end of the season’, when they’re already too late!
The peak summer bat survey season happens when it does for good reason, that is when bats are active and are likely to be present at key summer roosting locations. Therefore, surveys carried out during the season have a higher likelihood of accurately identifying the roosts. Yes, there are other surveys for bats that can be carried out at different times of year, such as Preliminary Roost Assessments (PRA), which can be carried out at any time of year, transect surveys to assess foraging and commuting, which can be carried out from April to October, and hibernation surveys, that are carried out during the winter, but those surveys are not the key surveys usually required to support a planning application to demolish, extend or otherwise alter a building.
After 20 years in ecology the pattern hasn’t changed, and every time someone misses the bat survey season it’s the bats fault, not theirs, their architects, the planners, or the plethora of other people who have spent the last 6 months advising them on all the things that they needed to do, prepare, or commission to support their planning application.
Why do we end up in this situation every year? There’s endless literature online stating when bat surveys need to be carried out. Most ecologists, including myself, have a year planner on their websites that outlines the optimum timing for surveys (Steven Whitcher, Year Planner), the Bat Conservation Trust Guidelines, the best practice guidelines that all ecologists should be working to, are online and widely available (Bat Conservation Trust Good Practice Guidelines, 3rd Edition) and if you google bat survey timings there are abundant results stating the correct times of year, although I do accept that some wrongly state May to September.
As a general rule, if you are applying for planning permission on a site that has existing buildings, trees, rocks or other structures there is a reasonable likelihood that a bat survey will be required, so get one done. PRA’s are a relatively inexpensive survey and can be carried out at any time of year to advise where further surveys are required during specific seasons.
The more commonly known the bat survey season is the better that will be for everyone. It would reduce the delays and costs involved waiting to carry out surveys, it would reduce the bad press for bats, and it would reduce the last minute stress on ecologists who all have run around with their hair on fire at the end of August praying that it doesn’t rain because they’ve got three weeks surveys to complete in a week.
So what do we need to get the message across, perhaps we should change our abbreviations to form reminders?
Preliminary Roost Assessment (PRA) - Pretty Reliable Anytime,
Bat Activity Surveys (BAS) – Before August not September.
Or perhaps a limerick is more memorable?
I seem to forget for some reason,
That Augusts the end of the season,
There is no debate,
Septembers to late,
Unless surveys have already been done,
Or do we just need to plan ahead and seek advice when we aren’t sure. A quick email, a message, or a phone call should be sufficient to get a second opinion from someone and potentially avoid unnecessary delays, additional costs, and further bad press for some of our most iconic, and highly threatened, species.