[APWG] Native "invaders"?
Wayne Tyson
landrest at cox.net
Mon Sep 17 11:10:51 CDT 2012
John,
It's adaptation, not "invasion." When the context changes, by human agency
or anything else, populations shift accordingly. Organisms and their
environment are in a continuous process of change. Doves and rodents, for
example, respond to increases in things like food supply (of course, it's
more complex than that, but food and water are the big variables that affect
most organisms.
I have concocted a "Law" of biology: "Organisms do what they can, when they
can, where they can."
Discuss?
WT
----- Original Message -----
From: "John"
To: "john
Sent: Saturday, September 15, 2012 2:14 PM
Subject: [APWG] Native "invaders"?
> Is there a word or phrase for those species that might be native, but
> because of their adaptability to humans and human actions, might be
> considered invasive species?
>
> I am not interested in rehashing the definition of invasive species,
> these are all native pre-human history. The negative impact on humans or
> the environment is lacking in some cases and clear in others. I am
> looking for another word or phrase to indicate those species whose
> population growth is directly tied to human action.
>
> I know that, in general, armadillo are not considered invasive species
> because they invaded under their own power without an assist by humans.
>
> In the Austin area, I can think of several bird species that were native
> to the area, but whose populations have exploded because of human's
> impacts on the environment.
>
> They are:
> White Winged Doves
> Boat-tailed Grackles
> Cliff swallows
> Blue Jays
> Purple Martins (I hesitate to include this popular bird, however......)
> Brown headed cowbirds
>
> The White Winged Doves used to be rare to endangered, then they learned
> to nest outside of South Texas thorny scrub and to visit backyard bird
> feeders. They have moved steadily north from south Texas to Dallas over
> the past 20 years displacing other dove species.
> Boat-tailed Grackles love to congregate in urban areas at night and
> forage in the surrounding suburban and rural areas during the day looking
> for bugs and grubs stirred up by tractors and lawnmowers.
> Cliff Swallows have expanded their range and numbers by using highway
> underpasses.
> Blue Jays are one of the most problematic. They follow the encroachment
> of suburban sprawl especially backyard bird feeders, then eliminate or
> displace the less aggressive Scrub Jays. Blue Jays are nest robbers, and
> one of the predators on our endangered Golden Cheeked Warbler and Black
> Capped Vireos.
> Purple Martins nest almost exclusively in human built houses.
> Brown headed cow birds have become year round residents because their
> natural affiliation with migratory Bison has been replaced by perennial
> cattle herds in fenced pastures.
>
> Any thoughts?
>
> john in Austin
>
>
>
>
> _______________________________________________
> PCA's Alien Plant Working Group mailing list
> APWG at lists.plantconservation.org
> http://lists.plantconservation.org/mailman/listinfo/apwg_lists.plantconservation.org
>
> Disclaimer
> Any requests, advice or opinions posted to this list reflect ONLY the
> opinion of the individual posting the message.
>
>
> -----
> No virus found in this message.
> Checked by AVG - www.avg.com
> Version: 10.0.1424 / Virus Database: 2437/5273 - Release Date: 09/17/12
>
More information about the APWG
mailing list