13 September 2017

A site survey for sore eyes: external urban pest control

Feature pest control | PPC88 September 2017

What happens when your survey shows evidence of rats, badgers, deer, foxes and even slowworms? Consultant Member, Urban Wildlife, sees some of the more challenging pest control problems coming through its doors. Gary Williams, Director of Wildlife Services, looks at some of the difficulties encountered when working in an urban setting.

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As technicians within the pest control industry we see many different scenarios on a daily basis, but it is how we assess and formulate treatment plans for these scenarios that can have major impacts.

An essential trait of a good technician is to be able to effectively survey the target area while assessing apparent issues and potential impacts, along with the client’s needs and requirements. It is this initial survey that provides the base formulation of a treatment plan, so what if we miss something?

As wildlife consultants we are no different to pest controllers in the sense that each scenario we visit has to be assessed on its own merits before a treatment plan can be implemented – but what happens when pests and wildlife converge?

We recently attended a site (approximately 1 hectare in size) where, on the first appraisal, one of the immediate areas of treatment required was a significant rat problem. Located in a large industrial estate, a number of commercial units were situated adjacent to a piece of grassland that was due for imminent development. A tarmac path providing a public right of way bordered the grass field area, allowing access to the industrial estate from the nearby houses.

To ensure no unauthorised access onto the grass field, small soil bunds were evident around the whole of the site. These soil mounds contained far too many rat tunnels to count! The large rat population meant that numerous individuals were observed throughout the day actively utilising these tunnels as well as the nearby industrial units. In fact, the rats were that accustomed to human presence they were more than happy to come and eat their lunch with you!

Our remit as wildlife consultants was to advise the local council if there were any ecological constraints to be considered when developing the land. While the rats do not pose a developmental impact, they do pose a significant health and safety issue that needed to be highlighted.

Our initial survey recorded the excessive rat population but also recorded one slowworm individual in the middle of the field, a nearby badger sett, two deer, foxes and red kites (foraging). So, which of these species do you think could be most significantly affected by a rat treatment proposal?

The rat tunnels were recorded as little as 1m and up to 50m away from the industrial units. The badger sett was located more than 20m away from the nearest rat tunnels, and the deer and foxes were using the brambles for harbourage. The site contained significant amounts of artificial refugia in various areas, which would provide suitable habitat for slowworms and the kites were regularly seen flying over. All of this information was apparent from our initial survey. What was not visually apparent but was invaluable information was the additional local knowledge sought relating to the site, especially about slowworms.

Various treatment proposals could be considered relevant to control the rat infestation and it is most likely that an integrated management approach would be considered in this scenario, but integrated or individual these treatments could have significant impacts.

As wildlife consultants, we would conduct specific surveys to ascertain baseline information on each species evidenced. Perhaps species numbers, primary affected areas, impacts and constraints relating to the proposed works are just some of the points we would then consider before implementing any treatment plans, but would you do this as a pest controller going to treat a major rat problem?

Some of the species identified

Some of the species identified

Rats predate slowworms, but only through local knowledge were we aware that the slowworms lived in the rat tunnels. Further ecological surveys would have identified this, but as a pest controller treating a rat infestation would you have anticipated them living in the same area? What are the impacts of burrow baiting?

Non-target species comes into direct contact with rodenticide:

  • Badgers and foxes predate slowworms, and rats, so could dig at the rat burrow and encounter rodenticide, possibly spreading it
  • Dogs and cats may also dig at the rat burrows

Non-target species encounters secondary poisoning in a burrow:

  • Snails and slugs eat rodenticide blocks
  • Slowworms predate the snails and slugs that could have eaten the rodenticide

Bait boxes with rodenticide?

If rodenticide is used in bait boxes implications in respect of secondary poisoning could be present in the form of dead rats being eaten by badgers, foxes and kites, additionally the local dog, cat and corvid population could also be affected.

Perhaps slowworms may use the bait boxes as artificial refugia and could then eat the snails and slugs that enter the bait boxes to feed on the rodenticide?

Bait boxes with snap-back traps could be used, but this would be costly to the client and would still pose some risk to slowworms, albeit minimal.

Within this one site, if you had used some of the most common treatments to control a significant rat infestation you may have contravened sections of the Badger Act 1992, the Wildlife and Countryside Act 1981, the Animal Welfare Act 2006, and CRRU UK Rodenticide Stewardship regime.

Obviously, an element of risk is involved with any treatment but it is how we minimise this risk that forms the basis of our recommendations. In this particular scenario, without adequate surveying and assessment, a pest control technician could encounter severe consequences.

While bait boxes with snap-backs may be considered too expensive, this is probably the safest and least risky option available – would you have recommended this on first appraisal of the site?
‘Urban’ wildlife is ever increasing, and we already know that many species are adapting to live successfully in environments that traditionally they were never found. Unless we begin to consider the diversity of our urban wildlife and adequately mitigate for them within our treatment plans, some species may not survive the test of time.

So what does the future hold for external urban pest control?

Let us know what you think. Email us.

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Gary Williams Urban Wildlife AuthorGary Williams
Urban Wildlife

15 September 2017  |  PPC88

Source: PPC88

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