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Invasive Species: Where do you draw the line?

Discussion in 'General Zoo Discussion' started by Panthera1981, 18 Nov 2014.

  1. Panthera1981

    Panthera1981 Well-Known Member

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    Interestingly, the UK now holds 10% of the world population of Chinese Water deer, a species introduced shortly after WW2 but not doing very well in its native homeland. Concurrently, grey squirrels now grossly outnumber the native reds, spreading diseases such as Squirrelpox. Globally, areas such as the Galapagos and Australia have also suffered similar scenarios.

    So, when do we say enough? Is it right that invasive species remain (let's not forget that rabbits were introduced by the Normans) or do we cull such invaders and invest in repopulating native species?
     
  2. gentle lemur

    gentle lemur Well-Known Member

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    You can only do what is possible. It is possible to exterminate introduced terrestrial animals on small islands (eg Round Island) or on moderately sized islands if the species is large (eg goats on Espanola/Hood) or on larger areas if it is only found in restricted habitats (eg ruddy duck and coypu in England) - but it is expensive.
    But exterminating abundant and widespread species such as grey squirrels, mink or brown rats from the UK would be impossible. Even myxomatosis failed to exterminate rabbits in the UK or Australia. Much the same applies to plants, we may be able to exterminate giant hogweed from the UK but we can only hope to control Himalayan balsam or Japanese knotweed.
    The situation is even worse with aquatic species: I don't know of any examples where an introduced species has been exterminated (perhaps it has been or could be done in remote desert springs in the USA to protect a pupfish for example). In the UK we will have to put up with signal crayfish, zebra mussels and Chinese mitten crabs. Much more serious are the lionfish in the Atlantic and the Nile perch in Lake Victoria, which are potential and actual ecological disasters.
    It is possible that new techniques for control and eradication may be developed for some species in some places one day. But prevention is infinitely better than cure!

    Alan
     
    Last edited: 18 Nov 2014
  3. zoomaniac

    zoomaniac Well-Known Member

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    One of my beloved themes here;)

    It's very difficult to draw a line. It depends on the facts/cirucmstances @gentle lemur mentioned.

    E.G.: IMO it does make sense not allow to import foreign TROPICAL snake species into Australia (at least not both genders of a species), while the bann in NZ for the same animal group don't.
    The risk that big ungulates imported FOR ZOOS may have for the nature and economics of a country is very low (as long as they live in controlled conditions). So it should be allowed (with the exception of suidae maybe). On the other hand, escaped small non-native rodents can be a very big problem, so imports even for zoos only are a high risk.

    That beeing said, we should not forget, that nature will find its way sooner or later. A complete protection is impossible in the global world of today...
     
  4. Pleistohorse

    Pleistohorse Well-Known Member

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    At small Island environments. Chinese Water Deer in the UK might compete with Roe Deer, but I think it far more likely each species will find its niche. Grey Squirrels do seem to outcompete Eurasian Red Squirrels, to the point where the species cannot exist in the same regions even, but species have been migrating to new areas for as long as we have had species on the planet. Blackbuck and Axis Deer in Texas. Camels and Banteng in Australia. Some positive conservation value can be attributed and should not be immediately discarded as unnatural and valueless. Even dangerous. Think of this. Some in the UK would like to reintroduce European Grey Wolves to Scotland. The native Scottish Wolf was 10,000 years removed from the nearest surviving wolves in Spain or Poland...why not take American Red Wolves (merits as a species aside) and introduce them into a perfect Coyote-free refuge...that is ecologically compatible with wolves...while at the same time, ensuring no risk to the remaining native European Wolves of being "polluted" with alien genes. This idea of Invasives can also be used to put the breaks on legitimate conservation projects. For example establishing populations of African Cheetahs in India. Or the Amur Tiger in Central Asia (although we might not be there yet as a viable plan). The Horse evolved in North America...yet economic interest (not that I'm opposed to those) and conservation orthodoxy team up against Horses and Burros as legitimately belonging on public lands. I'd go a step further and advocate using our current Horses and Burros to help sustain Condor recovery...while planning for the eventual introduction of Pzewalskis Horses, Somali Wild Asses, and eventually Guanacos to the American West. So cats and rats to flightless bird paradises no...but are all Invasives bad...also no.
     
  5. Chlidonias

    Chlidonias Moderator Staff Member

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    you are confusing/conflating "invasive" and "introduced". The two things are not the same.
     
  6. dean

    dean Well-Known Member

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    By a coincidence last week I listened to a programme on radio 4 with an expert on bumble bees, the funny thing was that the short haired BB is now considered extinct here in the UK, but by a quirk of fate it was introduced to New Zealand by an 18c settler who asked his cousin to send him some. They are now doing OK in NZ but for some reason -export ban from NZ what ever- we are going to reintroduce the bumble bee from Sweden.

    On the subject of Japanese Knot weed One of my gardens was owned by a famous family who introduced lots of plants from the orient for their Japanese garden, this included Knot weed, it eventually took over the whole area, but over a couple of seasons I have eradicated it from the Japanese garden, and it is kept under control elsewhere with a strimmer. Sadly the best chemical control has fallen foul of the EU chemical ban.
     
  7. Buldeo

    Buldeo Well-Known Member

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    In today's day and age, I would go so far as to ban much of the exotic pet trade. Absolutely nobody needs a twenty foot constrictor in their home. This would have assisted in the reduction of the biogenetic destruction of the Everglades.
     
  8. TheMightyOrca

    TheMightyOrca Well-Known Member

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    If I were to try and make a ban of exotic pets based on concerns over invasive species, I'd do it based on species and area. Some animals aren't likely to become invasive species in most or any areas. The python thing is a problem in Florida, but it wouldn't be an issue in, say, Minnesota.
     
  9. vogelcommando

    vogelcommando Well-Known Member

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    I'm affraid we have to live with invasive species. In some cases we can avoid them by banning some species from the exotic pet trade ( several squirrels, bull frogs ) but in most cases we don't have any influence. Marine animals transported by cargo-water in ships spread across the world and as soon as they find a suitiable envoirment, they will sattle.
    We have to make the best of it and if the species can be of any use ( for example food ), start to collect it and try to keep the population as low as possible.
     
  10. Chlidonias

    Chlidonias Moderator Staff Member

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    the expert may not be as expert as he claims....

    http://www.zoochat.com/65/bumblebees-going-nz-uk-122125/

    Perhaps the NZ bees didn't establish for some reason so they are trying European ones instead.
     
  11. dean

    dean Well-Known Member

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    I have listened to the programme again 'Radio4 A life scientific' on line again as I arrived at work before they got to the point.
    The NZ bees turned out to be to inbred and the DNA of the Swedish ones are more like the extinct British bees, than the bees sent out to NZ in 1895.
    Apparently the reason they were sent out to NZ was the settlers were sick of spending money importing red clover seed, as no native NZ bees could pollinate the flowers as they didn't have a long enough tongue. the clover was used as fodder for their livestock. The chaps name is Prof. Dave Goulson of Sussex University.

    The chap who asked for the bees also asked for hedgehogs, but they didn't say how the hogs had got on in the new country.
     
  12. Chlidonias

    Chlidonias Moderator Staff Member

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    that's interesting. The founder population of the bees would probably have been quite small of course.

    Hedgehogs - we have plenty. But we have no hedgehog fleas, they all died out on the boat trip over from England.
     
  13. lamna

    lamna Well-Known Member

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    I think sometimes environmentalism gets too hung up on trying to restore habitats back to the way they once were. It's impossible and we need to accept the landscape, flora and fauna of the world has changed and humanity is here to stay.

    That doesn't mean not trying prevent more introductions, or undoing the harmful ones but some plans seem spiteful and wastefully.

    Aesculapian snakes and Red Necked Wallabies can both be found in Britain, but they don't thrive, their populations just thread-water and they don't expand their range, but people still fuss about them and want them exterminated.
     
  14. Hix

    Hix Wildlife Enthusiast and Lover of Islands Premium Member

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    Again, by your description, these are not invasive species.

    :p

    Hix
     
  15. Pleistohorse

    Pleistohorse Well-Known Member

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    True Hix, however, when someone wants to remove or restore that is the term they use, be they business interest or greenies.
     
  16. Pacarana

    Pacarana Well-Known Member

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    Unfortunately the pet trade supplies the world's dedicated private breeders with endangered animals that many zoos do not try with. Take pangolins or borneo earless monitors. Zoos do not mess around with animals they know would be too difficult and private breeders are willing to try. So far there is a successful captive breeding group of earless monitors and if progress continues, pangolins will call private breeder's facilities home. Many people think banning the trade would help wild populations of animals, but in all honesty, many zoos would not be where they are now without the help of private individuals and exporters alike.

    And also boa constrictors rarely come in wild caught anymore. Most are now captive bred, so banning import would do nothing for the large snake availability.