Invasive animal species no.2 – Canada Geese

Canada geese were initially introduced to the UK as an ornamental species in the 17th century and since then they have flourished: the past forty years in particular have seen a significant increase in the population size.

They are attractive birds and the majority of people probably wouldn’t think twice about whether they are supposed to be in our parks and lakes – I wasn’t even aware that they were a foreign species until I began reading up on the topic a few weeks ago. Whilst much less emphasis is placed on them than other invasive species (grey squirrels, for example – see my previous blog post for more information), they do still have detrimental effects in British ecosystems.


Canada geese can cause damage to plant life – by eating aquatic plants they can disrupt oxygen levels in lakes, which has an impact on organisms in the water. On the sides of lakes, terrestrial plants such as grass are trampled and eaten. 

Their droppings can appear unsightly and contain substances which in large quantities could affect aquatic life – these include nitrate and phosphate. Continual entries and exits from the lakes can also cause erosion of the banks.


Certain people are eligible for a license which grants them permission to kill Canada geese and to destroy their nests and eggs. 

Some other less extreme methods can be used to manage populations: many are fed by humans, so discouraging this activity is an option and strategic fencing can prevent geese from settling in an area in the first place. 


Whilst this may be considered as necessary action to protect British lakes and parks, perhaps we should also recognise that Canada geese are not the only waterfowl to inhabit these areas and so are not the only species contributing to the problem. That said, they are on the rise and could begin to dominate over other native species that exploit the same niche. 

The idea of having to remove Canada geese due to us wrongly introducing them in the first place is a controversial one, but we have to understand that as an invasive species they could have a long term negative impact on British ecosystems.


Sources used in this blog post: 

The RSPB: 

English Heritage: 


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