Tag Archives: Amphibians

Invasive Species Week 2021: Invasive Alien Species of Herpetofauna in the UK

This is a guest post by Helen Tedds who is currently researching for a PhD at the University of Northampton. Although Helen’s work is far removed from my usual research and consultancy interests of plant-pollinator interactions, I’m proud to be part of her supervisory team! Amphibians were one of my early natural history obsessions, and invasive plants and pollinators are a long standing interest of mine. In this post Helen discusses her research on the UK reptile and amphibian pet trade.


This week (24th-30th May 2021) is Invasive Species Week, an annual event led by the GB NNSS (Non-Native Species Secretariat) to raise awareness of invasive species and how we can help prevent their spread. Generally, the term ‘invasive species’ is defined as an introduced organism that has an adverse impact on its environment by causing ecological and economic damage. They are one of the top five causes of worldwide biodiversity loss through habitat damage, preying on or out-competing other species. They can also spread disease to other species, including humans. The estimated cost of invasive species to the UK’s economy is more than £1.7 billion [1] which is caused by things like damage to buildings [e.g. from the dreaded Japanese Knotweed (Fallopia japonica – fig. 1)], interference with food production, delays on work projects, and the expense of dealing with them. The number of new species being introduced to the UK is rapidly on the increase and can be exacerbated by climate change. This is an urgent problem that without intervention will continue to escalate!

Fig. 1: Japanese knotweed (Fallopia japonica) damaging a brick wall

In 2015 I embarked on a PhD that aimed to quantify the pet herpetofauna (reptile and amphibian) trade across England, mainly to understand the associated socio-economic factors and animal welfare consequences of this. Investigating invasive species was low on my already-full agenda, however, it has been a rabbit hole I ended up going down (pun intended: rabbits were named Britain’s most costly invasive species in 2010 according to The Guardian[2])!  

The exotic pet trade has long been known to be a means of new species entering an environment (either through escape or deliberate release), but according to a recent study in Frontiers of Ecology it now ranks as a primary cause of invasive species[3]. It has long been illegal to release any non-native species into the wild under the Wildlife and Countryside Act 1981, however more recent legislation has been enacted to prohibit the trade of invasive species. Whilst the term ‘invasive’ can be subjective, in the UK a species officially considered to be invasive is listed in retained EU law: Invasive non-native (alien) animal species: rules in England and Wales. That’s not to say that other ‘feral’ pets are not ‘invasive’. There are concerns that Indian ring-necked parakeets (Psittacula krameria – fig. 2) that have spread across the UK are potentially out-competing some of our native birds for nesting sites in tree hollows[4]. However there needs to be a body of evidence built to support these claims before a species is added to the legislation.

Fig. 2: Indian ring-necked parakeet (Psittacula krameria)

In terms of herpetofauna, there is only one invasive species of amphibian listed in the legislation, the North American bullfrog (Lithobates catesbeianus- fig. 3), and one species of reptile, the common slider turtle (Trachemys scripta) along with all sub-species, including T. s. elegans, T. s. scripta, and T. s. troostii -fig. 4-6)[5]. North American bullfrogs pose a threat to our already vulnerable native amphibians as they will eat frogs, newts, and other similar sized animals[6], and slider turtles threaten our waterfowl as they will eat bird eggs, as well as insect larvae[7].

The law has prohibited anyone from keeping, breeding, and selling these species since August 2016. If you owned one before the law came into force (turtles can be very long-lived) then you have what are called ‘grandfather rights’ where the animal can remain in your possession until the end of its days. If an owner can no longer take care of the turtle they cannot re-sell it- it is best to relinquish them to a rehoming centre that has the relevant license where they can live out the rest of their lives[8], such as The National Turtle Sanctuary at Lincolnshire Wildlife Park[9].

Part of my research into quantifying the herpetofauna trade has involved sampling from pet shops and online classified adverts as to what species are for sale. So far, I have officially documented 431 different reptile species, and 122 different amphibian species[10], and this number is set to grow as I continue to analyse four years’ worth of data. All these species are non-native, and whilst most of them would not survive in our British climate, there are some causes for concern.

In October 2020 a fellow PhD student, Ali North, got in touch with me as she is currently investigating the drivers of establishment and spread of a non-native amphibian in the UK, the alpine newt (Ichthyosaura alpestris- fig. 7). Her project uses distribution data of alpine newts in their native range across mid-Europe with an aim to predict the invasion risk of this species in the UK[11]. I was interested to learn from her that these newts have established various populations in the UK but most concerningly are known to be a vector of chytridiomycosis which can be transmitted to our native amphibians[12]. As part of her research at the University of Plymouth, ZSL Institute of Zoology, and the ARC Trust, Ali wanted to know how often alpine newts had occurred in my data sampling seeing as the pet trade is a potential route for non-native species entering the wild. It turns out that my data set had only 16 records of alpine newts (out of tens of thousands of records) which is not very many, however, do not be fooled by small numbers! It does not take many individual pets being released into the wild for a potentially invasive species to wreak havoc on an ecosystem. Whilst the understanding of alpine newts as an invader is in its infancy, I was delighted to be able to assist Ali with this part of her research and I look forward to reading her final thesis. If you have spotted an alpine newt in the UK you can also help towards her project by reporting it here: https://www.arc-trust.org/news/have-you-seen-an-alpine-newt-in-the-uk 

Another interesting thing that my data collection has highlighted is that despite slider turtles being banned from sale for over four years now, they are still appearing on online classified websites such as Preloved, Pets4Homes, and Gumtree. Not only is this illegal, but it is also against the minimum standards set out by the Pet Advertising Advisory Group (PAAG) which these websites agree to adhere to as voluntary members[13]. Since I started collecting data in July 2017 to the time of publishing this blog there have been at least 102 adverts selling slider turtles, and these were the more obvious ones. On deeper investigation some adverts selling yellow-bellied sliders listed them as just the letters ‘YBS’ meaning that they would not be flagged when searching using key words. These adverts have consistently appeared in my data set at a rate of about two per month, with a noticeable spike in Oct-Dec 2020 at a rate of five per month, so there does not appear to be a downward trend since the legislation came into force. Also, some other adverts just listed animals using the word ‘turtle’ or ‘terrapin’; not only does this allow the potential for slider adverts to slip through the net but it also further violates PAAG minimum standards by not advising potential buyers what the species is. How can someone research the correct care information if they don’t know what species they are buying?

Another invasive species that I came into close contact with recently, coincidentally whilst in the process of writing this blog, was in my local park- Elmdon Park in Solihull. An invasive water weed, Azolla filiculoides, or red water fern (fig. 8), had suddenly appeared in one of the park’s ponds. This weed is believed to have entered UK water systems from the ornamental pond and aquarium trade either by spreading via birds’ legs between ponds or from people emptying fish tanks into wild water bodies. It spreads on the surface of water bodies, blocking out sunlight and decreasing oxygen, thereby killing native wildlife[14].

Fig. 8: Red water fern (Azolla filiculoides) in Elmdon Park, Solihull

I sit as Secretary on Elmdon Park Support Group’s[15] committee and run their social media pages, so I found myself reading more about this weed and treatments used to control it, in order to inform the local community on what would happen. The Warwickshire Wildlife Trust lease the land and therefore must foot the treatment bill, which turns out to be the use of a weevil (Stenopelmus rufinasus- fig. 9), affectionately known as ‘Weevil Knievel’ The weevil eats the weed but doesn’t come cheap at a cost of a few hundred pounds for just one container of them[16]. So here we have another casualty to our native wildlife because of the pet trade.

Fig 9: ‘Weevil Knievel’ (Stenopelmus rufinasus)

So, what can we do? Further research into identifying potentially invasive species will help in raising public awareness, whilst initiatives such as Invasive Species Week will spread the message on the consequences of releasing non-native species into our UK ecosystems. But there persists a deeper problem whereby some people fail to properly research the needs of the pets they buy, or fully understand how big they will grow, and feel that it’s easier to release them into the wild rather than to relinquish them via more responsible methods. This is perhaps the area of human-animal interactions that needs more attention and research.

References

  1. NNSS (2021) What are invasive species and why are they a problem? (online) Available from: http://www.nonnativespecies.org/index.cfm?pageid=640 (Accessed 6th May 2021).
  2. The Guardian (2010) Rabbits named Britain’s most costly invasive species (online) Available from: https://www.theguardian.com/environment/2010/dec/15/rabbits-invasive-species-cost#:~:text=They%20were%20introduced%20to%20Britain,infrastructure%2C%20a%20report%20says%20today. (Accessed 6th May 2021).
  3. National Geographic (2019) Why you should never release exotic pets into the wild (online) Available from: https://www.nationalgeographic.co.uk/animals/2019/07/why-you-should-never-release-exotic-pets-the-wild (Accessed 6th May 2021).
  4. RSPB (ND) Ring-necked parakeets in the UK (online) Available from https://www.rspb.org.uk/our-work/policy-insight/species/invasive-non-native-species/ring-necked-parakeets/ (Accessed 6th May 2021).
  5. GOV.UK (2020) Invasive non-native (alien) animal species: rules in England and Wales (online) Available from: https://www.gov.uk/guidance/invasive-non-native-alien-animal-species-rules-in-england-and-wales#leaving-the-eu (Accessed 6th May 2021).
  6. Froglife (2021) American Bullfrogs (online) Available from https://www.froglife.org/info-advice/amphibians-and-reptiles/american-bull-frog/#:~:text=The%20North%20American%20Bullfrog%20is,other%20animals%20of%20similar%20size. (Accessed 6th May 2021).
  7. Canal and River Trust (2020) Terrapins (online) Available from: https://canalrivertrust.org.uk/enjoy-the-waterways/canal-and-river-wildlife/the-rogues-gallery-of-invasive-species/terrapins (Accessed 6th May 2021).
  8. GOV.UK (2020) Invasive non-native (alien) animal species: rules in England and Wales (online) Available from: https://www.gov.uk/guidance/invasive-non-native-alien-animal-species-rules-in-england-and-wales#:~:text=You%20cannot%20legally%20keep%20these,these%20animals%20into%20the%20wild. (Accessed 6th May 2021).
  9. Lincolnshire Wildlife Park (ND) The National Turtle Sanctuary (online) Available from: http://www.lincswildlife.com/national-turtle-sanctuary/ (Accessed 6th May 2021).
  10. Tedds, H.L., Sneddon, S., Ollerton, J., Clubb, R., and McCormick, W.D., Herps across England: investigating the scale of the reptile and amphibian trade: UFAW Recent Advances in Animal Welfare Science VII Conference Poster, 30th June- 1st July 2020, online.
  11. ARC (ND) Have you seen an alpine newt in the UK? (online) Available from: https://www.arc-trust.org/news/have-you-seen-an-alpine-newt-in-the-uk (Accessed 13th May 2021)
  12. Inside Ecology (2018) Invasive non-native species (UK) – Alpine newt (online) Available from: https://insideecology.com/2018/01/04/invasive-non-native-species-uk-alpine-newt/#:~:text=The%20Alpine%20newt%20is%20known,accidentally%20be%20spread%20between%20waterbodies. (Accessed 6th May 2021).
  13. Pet Advertising Advisory Group (2018) Selling a pet (online) Available from: https://paag.org.uk/selling-a-pet/ (Accessed 6th May 2021).
  14. RHS (2021) Aquatic Weeds (online) Available from: https://www.rhs.org.uk/advice/profile?pid=429 (Accessed 13th May 2021).
  15. Elmdon Park Support Group (ND) About us (online) Available from: https://www.elmdonpark.org.uk/ (Accessed 13th May 2021).
  16. Birmingham Live (2021) Thousands of weevils to be realised in Solihull’s red lagoon (online) Available from: https://www.birminghammail.co.uk/news/midlands-news/thousands-weevils-released-solihulls-red-20580339 (Accessed 13th May 2021).

Figures

  1. Japanese knotweed https://environetuk.com/Blog/Does-Japanese-knotweed-cause-property-damage
  2. Female Ring-necked parakeet https://metro.co.uk/2021/01/01/parakeets-could-be-culled-by-government-after-rapid-rise-in-population-13834746/
  3. North American Bullfrog (Lithobates catesbeianus) https://www.invasivespeciesinfo.gov/aquatic/fish-and-other-vertebrates/bullfrog
  4. Red-eared slider turtle (Trachemys scripta elegans) https://canalrivertrust.org.uk/enjoy-the-waterways/canal-and-river-wildlife/the-rogues-gallery-of-invasive-species/terrapins
  5. Yellow-bellied slider turtle (Trachemys scripta scripta) https://www.petguide.com/breeds/turtle/yellow-bellied-slider/
  6. Cumberland slider turtle (Trachemys scripta troostii) https://www.virginiaherpetologicalsociety.com/reptiles/turtles/cumberland-slider/cumberland_slider.php
  7. Alpine newt (Ichthyosaura alpestris) https://insideecology.com/2018/01/04/invasive-non-native-species-uk-alpine-newt/#:~:text=The%20Alpine%20newt%20is%20known,accidentally%20be%20spread%20between%20waterbodies.
  8. Red water fern (Azolla filiculoides) in Elmdon Park, Solihull https://www.birminghammail.co.uk/news/midlands-news/warning-hidden-solihull-pool-turns-20484665
  9. ‘Weevil Knievel’ (Stenopelmus rufinasus) https://insideecology.com/2017/11/01/invasive-non-native-species-uk-water-fern/