Attempts have been made to hunt the species to extinction, but so far, the only progress that had been made has been to keep the communities from growing, as opposed to decreasing the number of animals outright.   The program suffers, as do many of the initiatives in the National Park System, from a lack of funding and manpower.  The hogs are still a threat to the plants and soil of the Great Smoky Mountains park.  One effective way to curb their population would be to issue permits to hunt the boars at a discount from the normal permits, and to issue a large number of them.  Wild boars are said to be a good hunt, and many people would find this an attractive offer.  In addition to letting the public do the work, the park would earn revenues, albeit not huge ones, by the sale of the permits.   These revenues could be channeled into a number of projects in the park, including the reduction of other exotic species.  The National Park System feels that since the hogs are not native to the park, their numbers should be brought down close to zero in order to maintain the ecological stability of the systems they affect.  Although it might prove a nuisance to other visitors on occasion, other parks have allowed hunting, in season and in regulated manner, and have found it to be an effective way to manage herd sizes.