Bat Survey - Barns, Kidwely, Carmarthem
Background
For this project, we surveyed a series of old barns that are due to be demolished to clear the land. These barns are all old and derelict, unused for years, with damaged walls and ceilings, vegetation overtaking many sections, making it impossible to navigate. Constructed using stone and hollow brick, there is plentiful access to the interior and several potential bat roosting opportunities within the structure.
Preliminary Roosting Assessment
As already mentioned, there was no lack of access into any of the barn structures. The roofs were either completely or partially missing, there were doorways without doors and windows without glass, providing free-flight access into the shelter for bats.
There was access into cavity walls, access into the hollow bricks, and gaps in the stonework, all of which could easily be utilitsed by bats as a safe and dark place to roost.
Within one of the barns, we found old bat droppings on the backs of some door, that appeared consistent with the size and shape of brown long-eared bats’ droppings. However, older droppings may not be suitable for DNA analysis due to the degradation that comes with time, so we took a sample but decided they would not be suitable for DNA analysis as a result of their quality.
When we have a building that is so highly suitable for bats, with evidence of their historic use, industry guidelines recommend a minimum of three dusk emergence surveys.
Dusk Emergence Surveys
We set up five cameras, a mixture of thermals and infrareds, around and inside the buildings we could access, and patrolled the site for two hours before and beyond sunset.
During our first survey, we picked up activity from brown-long eared bats, Natterer’s bats, and pipistrelle species. We recorded four bats entering and exiting one of the old barns. Not bad results for a first survey! This activity allowed us to hone-in on our second survey and strategically place surveyors and cameras during the subsequent surveys.
We got to site a little early during our second survey so we could inspect the features we saw bats take interest in based on our video review of the first survey’s footage. To our delight, when using an endoscope to inspect a cavity in some hollow bricks, we discovered a maternity colony of brown long-eared bats, recording mothers and their juveniles crawling around the roosting feature!
That night was a hive of activity - nine brown long-eared bats were recorded emerging from the feature we had inspected using the endoscope. We had also set up a camera inside the barn we saw bats emerging from during the first survey and recorded nineteen Natterer’s bats emerging from an interior wall of the barn. Throughout the evening, the Natterer’s bats returned back to their roost before leaving again. The number of bats and this behaviour of returning to the roost indicated that we had a maternity roost of Natterer’s bats in this series of buildings as well.
By the third survey, this maternity roost of Natterer’s bats had already dispersed and we recorded no Natterer’s bats emerging from this interior feature. We did record ten brown long-eared bats emerging from their maternity colony in the hollow bricks.
This was such an interesting site that we were privileged to be able to survey and record the bat usage of throughout the activity season!
Next Steps
The current owner’s plans were to sell the land, including the barns, with planning permission to demolish the current buildings on site and build a new garage. Our job is to ensure that our clients get to proceed with their development without compromising on the safety of bats. As such, a stipulation of the planning permission was to build a purpose-built bat house that would suitably replace both maternity roosts on site, allowing bats to return to this site for years to come to safely raise their pups.
