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So are these Grizzlies now an "invasive species" on Vancouver Island? Explain why or why not you think so!

karaterobot 2y ago
If they swam there, no. Invasive species have to be introduced by humans, by definition! The effect of grizzlies on the island ecosystem is unknown, and that may be more of what you're talking about.
- derefr 2y ago
  > If they swam there, no. Invasive species have to be introduced by humans, by definition! So what do you call it if humans introduce a species to an island A that's really close to another island B — and then the species happens to make the short hop to island B on its own? In a causal sense, that species would not have made it to island B if not for us introducing it to island A.
  - tempestn 2y ago
    Yes, when an invasive species spreads from where it was first introduced, it remains an invasive species.
  - karaterobot 2y ago
    The article says they probably swam across the Johnstone Straight, from the mainland. There's no mention whatsoever of introducing grizzlies to any nearby island. If you're asking hypothetically, I'd guess it comes down to whether the islands were separate ecosystems, but Wikipedia would be a much better source than me.
- cco 2y ago
  By what definition? Humans being involved didn't seem common in definitions I found.
  - morsch 2y ago
    An invasive species is an introduced species that harms its new environment. https://en.m.wikipedia.org/wiki/Invasive_species https://en.m.wikipedia.org/wiki/Invasive_species An introduced species, alien species, exotic species, adventive species, immigrant species, foreign species, non-indigenous species, or non-native species is a species living outside its native distributional range, but which has arrived there by human activity, directly or indirectly, and either deliberately or accidentally. https://en.m.wikipedia.org/wiki/Introduced_species https://en.m.wikipedia.org/wiki/Introduced_species
    - cco 2y ago
      > The term "invasive" is poorly defined and often very subjective. I too read the Wikipedia article and this sentence prompted me to survey a few other places. Federal law in the US for instance. Your quoted definition doesn't appear in the article covering _invasive_ species, only in "introduced species" which of course implies a human introduced them.
      - morsch 2y ago
        The first paragraph is Wikipedia's definition for invasive species as a kind of introduced species with additional attributes. It's the first sentence in the article. US federal law might be different, I wouldn't know.
dagmx 2y ago
The article says that grizzlies did use to exist on the island, so they’d not be invasive
- deleted 2y ago
  [deleted]
- fbarred 2y ago
  By that definition, horses that were introduced to North America by humans in 16th century are not invasive because they existed in North America 10,000 years ago.
  - pvaldes 2y ago
    So they fill a niche in a place that evolved with extinct horses and can sustain another species of horse. If they pass a threshold where they drink all the water for example (desert pools on Australia with endemic desert fishes), they became invasive and must go.
  - dagmx 2y ago
    The article also does say that Grizzlies come and go, that the significance here is it’s a female with cubs. So it’s not like grizzlies aren’t present at all on the island. Of course there could be a boom but apex predators tend to not be super boomy since they’d outstrip their own resources first.
pvaldes 2y ago
Not. Grizzlies aren't invasive here. A species is invasive basically if: 1) has been introduced directly or indirectly by man actions (a mosquito carried on a plane, a lost exotic pet). If arrived by its own means is not invasive. 2) is not a previous part of that ecosystem so it didn't evolved here; There are exceptions to this rule [1][2] 3) is reproducing in the new area (often explosively by lack of predators and diseases), also with some exceptions [3]; and 4) Will modify the ecosystem substantially (displacing or wiping other species in the process). Wolves on Yellowstone fulfill all points except 2. They aren't invasive. Apples on America don't fulfill points 2 and 4 so they are more healers than destroyers, and reproduce but not exponentially. ------------ [1] Can be ignored when the new species fill a niche from an extinct one, "Healing" the ecosystem. Gray wolves proven to be solid healers for example. Turkeys on Mauritius island could be the only birds able to spread the seeds of some trees unable to reproduce since Dodo went extinct. In this case we can do an exception to save dozens of native species from going extinct. [2] Creating deliberately a sanctuary of a non native species to reduce the risk of being extinct in their own place, is also allowed. [3] neutered domestic cats, gone feral, are invasive, because there is still a constant supply from other areas.
sandworm101 2y ago
No. Species are not static. Large predators like grizzlies and wolves move in and out of areas over decades as they alter prey relatioships. It is hard to describe how vast and unmonitored this part of BC actually is. It is comparabke to the empty parts of alaska, but without the roads. Nobody believes that this is the first, or last, mother grizzly on the island. It may be the first known, or first recorded in the last century, but it will have happened before multiple times. It will be nothing new to nature, not in the long run. Another island near vancouver (bowen) is said to have no black bears. But given the population density of bears surrounding the island, Bowen could have black bears instantly. All it takes is one pregnant female getting scared enough to make the swim. If they arent there now, they likely were there in centuries past.

If they swam there, no. Invasive species have to be introduced by humans, by definition! The effect of grizzlies on the island ecosystem is unknown, and that may be more of what you're talking about.

derefr 2y ago
> If they swam there, no. Invasive species have to be introduced by humans, by definition! So what do you call it if humans introduce a species to an island A that's really close to another island B — and then the species happens to make the short hop to island B on its own? In a causal sense, that species would not have made it to island B if not for us introducing it to island A.
- tempestn 2y ago
  Yes, when an invasive species spreads from where it was first introduced, it remains an invasive species.
- karaterobot 2y ago
  The article says they probably swam across the Johnstone Straight, from the mainland. There's no mention whatsoever of introducing grizzlies to any nearby island. If you're asking hypothetically, I'd guess it comes down to whether the islands were separate ecosystems, but Wikipedia would be a much better source than me.
cco 2y ago
By what definition? Humans being involved didn't seem common in definitions I found.
- morsch 2y ago
  An invasive species is an introduced species that harms its new environment. https://en.m.wikipedia.org/wiki/Invasive_species https://en.m.wikipedia.org/wiki/Invasive_species An introduced species, alien species, exotic species, adventive species, immigrant species, foreign species, non-indigenous species, or non-native species is a species living outside its native distributional range, but which has arrived there by human activity, directly or indirectly, and either deliberately or accidentally. https://en.m.wikipedia.org/wiki/Introduced_species https://en.m.wikipedia.org/wiki/Introduced_species
  - cco 2y ago
    > The term "invasive" is poorly defined and often very subjective. I too read the Wikipedia article and this sentence prompted me to survey a few other places. Federal law in the US for instance. Your quoted definition doesn't appear in the article covering _invasive_ species, only in "introduced species" which of course implies a human introduced them.
    - morsch 2y ago
      The first paragraph is Wikipedia's definition for invasive species as a kind of introduced species with additional attributes. It's the first sentence in the article. US federal law might be different, I wouldn't know.

dagmx 2y ago

The article says that grizzlies did use to exist on the island, so they’d not be invasive

deleted 2y ago
[deleted]
fbarred 2y ago
By that definition, horses that were introduced to North America by humans in 16th century are not invasive because they existed in North America 10,000 years ago.
- pvaldes 2y ago
  So they fill a niche in a place that evolved with extinct horses and can sustain another species of horse. If they pass a threshold where they drink all the water for example (desert pools on Australia with endemic desert fishes), they became invasive and must go.
- dagmx 2y ago
  The article also does say that Grizzlies come and go, that the significance here is it’s a female with cubs. So it’s not like grizzlies aren’t present at all on the island. Of course there could be a boom but apex predators tend to not be super boomy since they’d outstrip their own resources first.

pvaldes 2y ago

Not. Grizzlies aren't invasive here. A species is invasive basically if: 1) has been introduced directly or indirectly by man actions (a mosquito carried on a plane, a lost exotic pet). If arrived by its own means is not invasive. 2) is not a previous part of that ecosystem so it didn't evolved here; There are exceptions to this rule [1][2] 3) is reproducing in the new area (often explosively by lack of predators and diseases), also with some exceptions [3]; and 4) Will modify the ecosystem substantially (displacing or wiping other species in the process). Wolves on Yellowstone fulfill all points except 2. They aren't invasive. Apples on America don't fulfill points 2 and 4 so they are more healers than destroyers, and reproduce but not exponentially. ------------ [1] Can be ignored when the new species fill a niche from an extinct one, "Healing" the ecosystem. Gray wolves proven to be solid healers for example. Turkeys on Mauritius island could be the only birds able to spread the seeds of some trees unable to reproduce since Dodo went extinct. In this case we can do an exception to save dozens of native species from going extinct. [2] Creating deliberately a sanctuary of a non native species to reduce the risk of being extinct in their own place, is also allowed. [3] neutered domestic cats, gone feral, are invasive, because there is still a constant supply from other areas.

sandworm101 2y ago

No. Species are not static. Large predators like grizzlies and wolves move in and out of areas over decades as they alter prey relatioships. It is hard to describe how vast and unmonitored this part of BC actually is. It is comparabke to the empty parts of alaska, but without the roads. Nobody believes that this is the first, or last, mother grizzly on the island. It may be the first known, or first recorded in the last century, but it will have happened before multiple times. It will be nothing new to nature, not in the long run. Another island near vancouver (bowen) is said to have no black bears. But given the population density of bears surrounding the island, Bowen could have black bears instantly. All it takes is one pregnant female getting scared enough to make the swim. If they arent there now, they likely were there in centuries past.