Of course the introducers of gallinaceous game birds were primarily interested in providing something to shoot, but in their view the system was deficient in species and this suggested an opportunity. Some mistakes were made in the process. So we have catchable eastern warmwater fish species (bass, sunfish, bullheads, walleye) crowding out less catchable/tasty native species. Then we have the well-intentioned effort to improve wildlife habitat in the semiarid Columbia Basin Plateau -- black locust and Russian olive were the species of choice since the region didn't seem to have suitable native upland trees -- a vacant niche. The Russian olive can reproduce in its own shade, its dense thickets have taken over a lot of meadow and riparian areas and it is now considered a weedy invasive.
So I'm thinking, as Bill suggests, that we can hold either a rigid view that all manipulation of natural systems is bad, or the equally rigid view that anything we can do to improve systems for our benefit is good. There is a middle ground. Warren W. Aney Tigard, Oregon -----Original Message----- From: Ecological Society of America: grants, jobs, news [mailto:[EMAIL PROTECTED] Behalf Of William Silvert Sent: Thursday, November 22, 2007 2:04 AM To: [email protected] Subject: Re: Invasives The idea that vacant niches do not exist is basically founded on a strict interpretation of Hutchinson's definition. It is the kind of rigid view that holds back science. Invasive species are successful either because the occupy a vacant niche or because they force closer packing of occupied niches. For example, if you remove all the top predators from a system then lower trophic levels explode, and there is a vacant niche. If you remove wolves, then deer populations grow and you may have to hire hunters to fill the empty niche. I'm not disputing that some introductions are based on fallacious arguments, but invoking the literal word of Hutchinson doesn't contribute much to the discussion. Bill Silvert ----- Original Message ----- From: "Randy Bangert" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Wednesday, November 21, 2007 9:54 PM Subject: Re: Invasives > It seems to me that these exotic gallinaceous birds were really > introduced to have something different to shoot. Using them to occupy > vacant niches appears to just be a convenient excuse foisted on us. > After-all, are there really "vacant" niches? One perspective suggests > that the niche is defined around the species, so 'vacant' niches do > not exist. Another specious triumph for wildlife biology.
