Carrying out a bat exclusion job on a fish wharf was a one of a kind job for KR Pest Control. Learn about the challenges and the solutions.

As with any major new developments, site surveys are carried out as part of the planning process. If native animals are discovered, a suitable management plan needs to be put in place. Such was the situation at the site of the proposed new fish market in Sydney, where a population of micro bats were found under the wharfs associated with the planned development.

Micro bats is the name given to a small to medium sized group of bat species weighing between 3 – 150g. From an evolutionary point of view, these generally insectivorous bats are thought to be a completely separate group to the much larger fruit bats. The micro bat colony found at the wharf was Myotis Macropus (southern Myotis), a small bat weighing up to 15 g with a wing span of around 28 cm. It tends to live near water in order to forage over waterways for insects or to catch small fish by dragging their feet across the water surface.

Being a native animal they are protected, so before the development could proceed it was necessary to develop a plan to protect the bats. The site’s ecologist determined that exclusion from the wharfs and the provision of alternative nesting sites was the appropriate strategy.

But the question was how to exclude bats from such a challenging location? Not only was the under wharf area substantial – some 600 linear metres – but any exclusion measures would need to be able to deal with high wind situations, variable water levels and obviously a corrosive (salty) environment. The initial installation would also need to have a design feature that allowed for the one-way movement of the bats, such that on exiting in the evening they were not allowed to re-enter. Of course installing such as system over water provided a challenge in itself.

The wharfs with bat exclusion sheeting installed

The site ecologist knew what was required, but needed to find a company with the skills to design and install a suitable management system. Having had experience of their bird managements skills, the State Government client through their agents CI Australia, recommended the appointment of Mark Jenner of KR Pest Control.

KR Pest Control focus primarily on commercial pest control on the east coast, from Noosa down to Canberra, but with a significant amount of their business in Sydney.

The team at KR Pest Control with Mark Jenner third from right

“We were certainly excited to get the call,” said Mr Jenner. “Although we hadn’t worked with bats before, being primarily a commercial pest control company we are used to dealing with large and complicated bird and rodent jobs, so we were confident in being able to come up with a solution.”

However, the time pressures were significant. Not only did they only have four days to submit a proposal, but the installation needed to be completed before winter, in order to exclude the bats before breeding season commenced. If this time window was missed, the exclusion would have to be delayed until the following year, with a corresponding delay in the fish market development.

Installing a two metre length of sheeting to the wharf

“The whole project was certainly a significant challenge. But our team loves problem solving and using our bird management experience, we just worked through the issues one at a time under the guidance of the ecologist, to develop a workable solution,” said Mr Jenner.

“Once we started pulling the design proposal together, we had to start thinking as engineers – figuring out how we were going to get it to move with the tide and how we were going to deal with the wind, to prevent the exclusion material turning into a massive sail!”

KR Pest Control selected an off-the-shelf building material – Burwell Envirogard, a plastic sheeting reinforced with a fabric mesh – which was tough, easy to work with and affordable. The material is typically used to wrap building sites for dust management.

It was important the material was breathable to allow wind to pass through and had the necessary flexibility, in order to fall and rise with the tide to ensure continuous exclusion. KR Pest Control called on their bird netting experience to decide on fixings, especially the need for stainless steel due to the corrosive environment.

The site consisted of two wharfs split into three sections and the exclusion material was installed in each of the sections in turn. The material was installed as a ‘curtain’ in two metre lengths to encase a section. Three two metre lengths were left open through which the bats could get in and out. The ecologist then monitored the bat movements through these openings so that the number of bats in a section could be determined.

“Whilst this monitoring was ongoing it was vital that the rest of the section was secure, to ensure that the counts were accurate,” explained Mr Jenner.

When ready to exclude the bats, the ecologist would drop one of the curtains, leaving two open, and count to make sure all the bats exited. On the second night they would drop the second curtain only leaving one open and on the last night, once all the bats had exited, they would drop the last curtain, completing the exclusion.

“We would then move on, and repeat the process on the next section of wharf,” said Mr Jenner.

On one wharf where the bats were being a bit stubborn, one-way exits also designed by KR Pest Control, were installed. Consisting of a 1200 mm x 1200 mm piece of plywood with a small square cut in the middle, the inside of the exit housed a landing platform which the bats could reach by climbing up some shade cloth. The bats would then exit through the hole and a standard one-way door.

“The ecologist was so impressed with the design he requested that we manufacture extras for them to use elsewhere,” remarked Mr Jenner.

Outside of the one-way exit

The installation meant the team had to work on a boat around the clock for two weeks to carry out the installation, which added to the challenge. As part of the management plan, it was also important to provide alternative bat nesting sites.

“The ecologist found potential nest sites on different wharfs nearby. We installed timber bat boxes under the instruction of the ecologist. Whilst we don’t monitor the boxes ourselves, we do take the ecologist out in our boat to inspect these boxes under the wharf,” said Mr Jenner.

Not only was this a significant installation job, it is now providing KR Pest Control with an ongoing income stream from maintenance activities.

“Generally there are weekly inspections, although when the wind exceeds 30 km/h, it becomes necessary to carry out daily inspections. Pricing is based on these inspection requirements plus an hourly rate for any repair work, which takes into account the need to use two technicians and cover boat costs,” explained Mr Jenner.

Being such a unique installation has required the KR team to learn on the job. “For example, we found that the 2.5 mm stainless steel wire was snapping in higher wind conditions. This was solved by using double wire and tying it looser, so it moves with the wind.”

Rising to the challenges of this particular job and the sense of achievement at its successful outcome, Mr Jenner hopes this success will enhance the reputation of KR Pest Control as an expert in commercial pest control, able to take on large and challenging jobs for a variety of commercial and government clients.

“It was a lot of fun but a tough couple of weeks. But by protecting the bats and having a happy client, makes it all worthwhile.”

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