Invasive Species Tips & Training

Category : Kieran Cowhig

With all the talk about aliens in the news lately you definitely might have some questions. It might, however, be a surprise for you to learn that aliens have been here in Ireland now for decades. While they may not take the form you might expect (or come from outer space either), aliens are a very big problem here in Ireland. Known as Invasive Alien Species (IAS), these are animals, plants, pathogens or other living things that would not naturally occur in Ireland but have arrived here as a result of human activity. Upon introduction, they become established and begin to thrive which can have many negative impacts such as outcompeting our native wildlife, disrupting the natural balances of ecosystems and even affecting our way of life and economy. Invasive Species live among us and spreading awareness about them is key to preventing their invasion from spreading.

Back in 2013 a team attempting to work out the economic cost of invasive species and non-native species in Ireland and Northern Ireland estimated the total IAS costs for the Republic of Ireland were at €203 million per year (Kelly et al., 2013). This was a decade ago and with the introduction of many new species since then, this is very likely a massive underestimation of their present day cost. More recently a new economic analysis released in 2021 suggests the situation is far worse. The authors said “should successful management interventions not be introduced, the costs to Ireland of IAS will rise to €26.5 billion per year by 2030 for all IAS” (Lucy et al., 2021)

I recently helped to deliver a course to communities in west Limerick around the management of IAS. I have compiled some tips for individuals looking to get involved with the fight against invasive species.

Invasive Species Tips

Make a site-specific management plan

As the old saying goes “fail to prepare, prepare to fail”. This could not be more true when it comes to working with invasive species. Invasive aliens are very resilient and pervasive. They don’t want to go away and so they have various strategies to ensure their survival. To ensure that you have the best chance of eradicating an invasive species, it is essential that you have a plan in place that spans at least 5 years, laying out the steps you need to take. There have been countless cases around the country where great work was initially carried out in the removal of an IAS only to then be followed by a lapse of time where the area was not being monitored. This resulted in the IAS coming back stronger than ever and in some cases even developing resistance to the treatment being used!  This can be very frustrating and disheartening to a group considering how labour intensive the work can be in the early stages of treatment. Among other things, your plan should also take into account the invasive species infestation within the context of the greater catchment. Invasive Species often grow along rivers, such is the case with Giant Hogweed. If you were to treat Giant Hogweed in your town without checking the extent of its presence upstream in the catchment, all of your work could be in vain. Giant hogweed spreads by way of the large flower heads at the top of its stalk. Just one flower head alone can hold as many as 5000 seeds and one plant capable of holding up to 50,000 viable seeds! If a giant hogweed plant was present upstream of your town and was not being managed many of these seeds will fall into the river where some will inevitably end up being washed up on the banks of the river where you are working so hard to remove the plant.  This highlights the importance of my next point.

Join or start a group- Collaboration is key.

While you might be all enthusiastic about treating invasive species right now. To ensure longevity, it is crucial that you link up with your community. No one person will beat this problem by themselves, we need to join forces. There are of course many benefits to this too. By linking up with your community or other community groups we can share ideas and learn from the experiences of others who might be a bit further down the path than we are. It can also become a sort of a social event and a great chance to meet like-minded people. Organising an event to deal with invasive species like Balsam Bashing can draw big numbers and also has a certain feel-good factor too as you can visibly see the fruit of your labour. Many times, groups will head for a coffee or even a pint after these sessions and can even be the beginnings of forming a bigger more social group. As mentioned above, if you are working alongside a river, as many groups will be, it is always worthwhile to check if there are groups working up and downstream of you.  Sometimes groups may even share labour to help you as we all work towards a common goal.

Know what is within your sphere of influence

Some invasive species are tricky to deal with. Improper management can actually exacerbate the problem. Some species will require professional attention due to their resilient or dangerous nature. The methods used to manage them are just not available to members of the public due to the nuance involved in their effective treatment. Sometimes they are just too dangerous, such is the case with Giant hogweed (see below). Pick species that community groups have a proven track record in successfully managing. Regardless of the species involved, recording and mapping their presence will always provide invaluable to those who can manage invasive species.

Record and map their presence

A simple yet very effective step that you can carry out is to make a map of the extent of invasive species in your area. This step is essential before you begin work to manage IAS. Understanding how pervasive a species might be, will often determine how you go about managing it. It may also guide you as to where might be the best place to begin works. Even if you don’t intend to manage IAS yourself, mapping and sharing records of their presence can be really helpful to our local authorities. By mapping or recording them every year we can see how quickly they might be spreading or how effective a treatment might have been. This can help drive decisions about which species should be focused on first. Mapping and recording are also key parts of your site-specific management plan. Remember, that which gets measured, gets managed!  You can share any records you make on the National Biodiversity Data Centre’s website(https://records.biodiversityireland.ie/start-recording).

Follow biosecurity measures

One of the best ways you can help to tackle invasive species is to prevent their introduction into a habitat in the first place. While this might seem like I am stating the obvious, you would be shocked by how often this step is overlooked. If you like gardening, try to buy native plants where possible, they will also help support our native wildlife much more too. Before you buy exotic plants, check to see if it is an invasive species (you can do this by going to invasives.ie).  Never take a slip of a plant while away on foreign holiday, while they may look lovely and harmless, back in Irish habitats they may be extremely invasive and damaging to native wildlife. It can be hard to believe but there have been cases where known IAS were still available for purchase in garden centres and were still being recommended by prominent gardeners while works to manage their spread were ongoing. Never release your pets into the wild; they can end up in ponds or spreading into local habitats disrupting the balance of local ecosystems. They may not stay local either and in some cases have been known to spread across the entire country. Did you know that the introduction of the Grey Squirrel, which has decimated our own native Red Squirrel can be traced back to a single event. In 1911, a wedding present from the Duke of Buckingham, a basket of American Grey Squirrels were ceremoniously released onto the grounds of Castle Forbes in Co. Longford. While the activity may have at the time seem innocent enough, these handful of squirrels were the first of their kind in Ireland and went on to colonise much of this island. There are three steps to always consider when you are out and about. Check, Clean, Dry. To learn more about this check this article here about biosecurity protocols.

Work with the relevant authorities

Invasive species are not picky about where they establish. Oftentimes you may find yourself dealing with a large infestation within the boundaries of a protected area such as a Special Area of Conservation (SAC) or a Special Protected Area (SPA). These sites are protected due to the rarity and or sensitive nature of habitats and wildlife found within them. If we are not careful and take into consideration the nature of these sites, treating invasive species could actually have a seriously harmful impact on the native wildlife. IAS can also establish alongside or within rivers which may have spawning grounds of fish like Atlantic Salmon nearby. Using the wrong treatment here could be devastating to local fish stocks. For this reason, it is always advised to consult with Inland Fisheries Ireland and LAWPRO whenever you work along rivers (You can find out who your local Community water officer is by looking on this webpage here(https://lawaters.ie/team/communities-team/#filter=*)) To find out about the location of Ireland’s protected sites you can look on NPWS.ie(https://www.npws.ie/protected-sites) or contact your local wildlife ranger. They can also give you guidance about how best to proceed.

Study your opponent

Understanding your opponent can mean the difference between success and failure. There are so many factors to consider when choosing how to tackle an invasive species. Understanding the different stages of its lifecycle, what type of habitat does it originate from, does it have natural predators? How does it interact with other species? What means does it use to spread? For example, when working with Himalayan Balsam, it is crucial that you begin work to remove it before it goes to seed. This plant spreads by way of its exploding seed pods. Triggered by motion, the explosion can send seeds up to six metres away!   If you do your work while they are present, you could actually make the infestation worse and end up helping its spread.  Another common invasive species, Giant hogweed can also be very dangerous to work with. Without proper PPE you could get seriously injured with severe rashes which will repeatedly erupt for up to 3 years in some cases.  By knowing your opponent. you can then decide how best to approach it. Is it best to treat it chemically, physically or biologically? When is the best time of year to approach works? All of this will determine how successful you will be in the long run and will make sure that you don’t end up causing more harm than good.

If you or a community group you are involved with are interested in learning more about how to manage local invasive species you could apply to your local Development Company for funding to run invasive species training . This way you can learn the ins and outs of how to successfully survey your community and write up your very own IAS management plan. The beauty of applying for funding this way is that it is 100% funded  so there is no need for you to match fund.You can find out who your local development company by viewing the ILDN members directory on this webpage here (https://ildn.ie/directory/local-development-companies-map/)           

Links in article





Kelly, J., Tosh, D., Dale, K. & Jackson, A. (2013). The economic cost of invasive and non-native species in Ireland and Northern Ireland. Report to the Northern Ireland Environment Agency and the National Parks and Wildlife Service. Available online: https://invasivespeciesireland.com/wp-content/uploads/2010/07/Economic_Impact_Assessment_FINAL_280313.pdf

Lucy, F., Caffrey, J. & Dick, J.(2021) Invasive alien species in the Republic of Ireland: Policy recommendations for their management . Report for the Water Forum Available online: https://thewaterforum.ie/app/uploads/2021/12/Lucy-et-al.-Invasive-Alien-Species-Report_Policy-Recommendations-for-their-Management.pdf