The price of eggs

The lockdown on poultry keepers that started in December 2016 to contain the spread of avian influenza brought into sharp relief the need for biosecurity measures in everyday commercial and recreational activities.  The outbreak spread from an initial isolated case in Lincolnshire in December, with further cases subsequently reported in Scotland, Leicestershire, Wales, Somerset and Northern Ireland. Pancake Day 2017, the biggest egg-buying day of the year, was supplied for many by eggs branded as free range that had been laid by hens housed under cover due to the emergency measures.

So, what has the price of eggs to do with development site management?


The avian flu outbreak in wild and domestic bird populations is a timely reminder of the importance of maintaining a high level of biosecurity to stop the spread of invasive species and diseases when working on development sites.

Biosecurity is not a term with which many people are familiar, but control failures can have a devastating effect on markets and the environment. Whilst health risk to the public of the recent UK outbreak is very low, the impact and costs on the poultry and food industry, and on conservation organisations such as the Wildfowl & Wetlands Trust (WWT) and bird collections, has been substantial. It’s too early to assess the cost to UK agriculture and food sectors but, as a comparison, the 2015 outbreak of avian flu in the US caused the wholesale price chicken eggs to jump by 84.5% in just one month, equating to nearly 20% of food production sector price costs.

Here in the UK it has been estimated there are nearly 2,000 established non-native species, 10-15% of which cause significant adverse effects. Whether these effects are environmental, economic or social they all come with a price tag, and it is estimated £1.7 billion is spent annually on the control of invasive non-native species in the UK.

Here at the Landmark Practice we have recently worked on a site supervising the eradication of New Zealand Pygmyweed (Crassula helmsii) from a pond in a major new residential development. This plant, also known as Australian or swamp stonecrop, was first introduced to the UK in the early 1900s as an oxygenating pond plant. It has since spread across Britain and Europe, mainly through the movement of vegetative fragments on boats, machinery used to manage water bodies, clothing and wildfowl. Once introduced to a water body this species grows rapidly and forms dense mats over the surface of the water, effectively choking other species of aquatic plant and causing the oxygen levels of the water to fall.  This makes the pond environment unsuitable for fish, amphibians and invertebrates.

Landmark’s client, the developer, was aware that New Zealand Pygmyweed is included in Part II of Schedule 9 of the Wildlife and Countryside Act 1981 (as amended) which states that if any person plants or otherwise causes the species to grow in the wild, they shall be guilty of an offence. Anyone convicted under Section 14 of the Wildlife and Countryside Act 1981 may face a fine of £5000 and/or 6 months imprisonment, or 2 years and/or unlimited fine or indictment.

If the constraints of working with this highly invasive species were not enough, the contaminated pond is populated with great crested newts. This means that use of chemical control in the volume required to eradicate the plant could not be used without injuring or killing the legally protected great crested newts, and there is currently no known biological control of this species. Mechanical control was not an option as fragments of New Zealand Pygmyweed produced by cutting and tearing will regenerate, causing the infestation to regrow and possibly spread. The plant is also highly tolerant to shade, frost and drought, so cannot be eradicated using environmental manipulation.

Given the above constraints the only option available to enable legal compliance was manual removal, which involved draining the pond, removing all vegetation matter by capturing it within the pond liners, taking up the liners and spraying with an appropriate herbicide before reinstatement of the pond. All contaminated matter had to be removed to a waste facility licenced to deal with this type of material.

Avoiding infestation

It appears that, in the above case, the contamination was imported with the pond liner and/or vegetation when the pond was originally created.  The eradication exercise has been costly and time consuming for our client, and could easily have been avoided had best practice biosecurity measures been implemented when the original site works were done. It highlights the importance of sourcing products from reputable companies who follow best practice biosecurity precautions and deliver work to a high standard.

This is just one example.  Landmark has also recently been involved in removing one of the most common and well documented invasive species on development sites.  Japanese knotweed (Fallopia japonica) is estimated to cost the British economy approximately £166 million per year (source: The Great Britain Invasive Non-native Species Strategy August 2015). It had been inadvertently introduced to this site on machinery that had not been cleaned properly after working previously on a contaminated site.  The source was not difficult to track.  The resultant stands of knotweed mirrored the locations where those machines had sat during the development works.

Lack of biosecurity can have truly devastating consequences on ecological balance.  The recent outbreak of crayfish plague responsible for major loses of White Clawed Crayfish (Austropotamobius pallipes) in Gloucestershire, Shropshire and Worcestershire, was almost certainly caused by transmission through water and mud on boots, bike tyres or fishing tackle.  Crayfish plague, a fungal disease carried by the invasive American signal crayfish which has already wiped out the vast majority of the UK population of the rare and legally protected White Clawed Crayfish, can survive for up to 22 days on damp clothes or equipment. Something we should all bear in mind whether working around water or using facilities in our leisure time for fishing or dog walking?

Here at Landmark biosecurity is something we take very seriously. Our ecologists work between different sites throughout the country, often in water where the risk of cross contamination is high. When leaving site we routinely clean off any mud or vegetation and remove any standing water from equipment and clothing. We then treat any survey equipment that is potentially contaminated with a specialist disinfectant capable of killing fungal spores prior to redeploying it. These are simple and straightforward measures, which developers and their agents should insist that all site operatives should apply.

This article is part of a series on invasive species.  If you need more information about those mentioned above, or others, please contact Pippa Cope at: