Biosecurity and Non-Native Animals

Hidden below murky waters or hibernating in river banks, concealed high up in trees or only coming out at night, these are some of the traits that may mean some invasive and non-native animals go unseen. Unlike the more visible and immobile plants, the presence of INN animals may not be at the forefront of our minds when thinking about invasive species on construction sites, and as such, the damages they can cause also risks going unseen.

Furthermore, the movement of plant and materials on and between sites may be less likely to spread animals than spread the seeds and vegetative parts of plants, yet the risk of spreading disease harmful to native animals and livestock is very high.

In this article we explore the INN animals that could be present and their implications:

The American signal crayfish was introduced by the British Government in the 1970s from North America to act as an additional and lucrative revenue due to their size, rapid growth and reproduction and are less fussy about what they eat; in contrast the native white-clawed crayfish (WCC) are much smaller, produce far less eggs and susceptible to crayfish plague. However, many signal crayfish escaped from farms, quickly and aggressively coloning waterways, eating fish eggs and digging deep burrows which undermine riverbanks. Signal crayfish outcompete native and protected white-clawed crayfish and are carriers of crayfish plague, resulting in the near eradication of WCC. It is possible however for both species of crayfish to be present in the same watercourse in close proximity if movement is limited by a physical barrier such as dam, weir or waterfall. As such, it is vital that all plant is cleaned, disinfected, checked and dried (>24 hours) before arriving on site and potentially when moving between locations on the same watercourse. If disease or species are spread to new areas, especially those where native species are present, this would constitute an offence under the Wildlife and Countryside Act 1981 (WCA). Furthermore, native crayfish are sensitive to silt pollution, clogging gills and smothering feeding ground; as such construction work needs to maintain a pollution prevention plan.   

A new and emerging threat has entered Britain as recently at 2010, these are known as killer shrimp. Two species are known within the UK and both are highly invasive, resilient and voracious predators. They indiscriminately eat other invertebrates and small fish which significantly alter ecosystems. Being only a few millimetres long and able to survive for up to 5 days in damp conditions, strict biosecurity measures must be implemented on any site where plant and machinery are used within the watercourse as once in an ecosystem, they are impossible to remove. Though they are not currently listed under legislation, as a non-native species with the potential to cause serious harm to ecology (especially to protected and notable species already under threat), it could be an offence to release or allow the escape of this species into the wild.

Other species such as rabbits, grey squirrels, mink and muntjac deer are all introduced species. Rabbits cause crop damage and land degradation and erosion, grey squirrels spread deadly disease to native reds, mink cause damage to wildlife, fisheries and game and domestic bird and muntjac damage our woods. Under the Pests Act 1954, rabbits must be controlled on the owners land in England and Wales as they are designated as rabbit clearance areas. Grey squirrels, mink and muntjac are listed under schedule 9 of the WCA and therefore if caught on site, it is illegal to release them into the wild, or allow them to escape. If pest species are caught on site, even accidently, considerations on humane dispatch may be required.