Wondrous Wildlife
By Vern and Lori Gieger
Alien Species

     Over the years we have become accustom to rescuing a variety of animals; however, some of our recent rescues such as crocodiles, green iguanas and numerous red ear sliders (a type of turtle) are worrisome. Why? They don’t belong here; not in this part of Mexico. But the grand prize winner is the grey cockatiels...that’s right, cockatiels. 
     Not long ago I spotted a pair of grey cockatiels in a nearby tree. They are cute little birds, but they are most definitely not native to our area, or even Mexico for that matter. One may think it is not that big of deal, but it can become one. Species of plants and animals that are not native to an area are known as: non-native species, alien species, invasive species, etc.
     Loss of habitat constitutes the greatest threat to the existence of native species and biodiversity. The second worst threat is the biological invasion of non-native plants and animals. Established ecosystems have developed their own natural balance over time, and the plants and animals within those systems have adapted to survive within existing conditions.
     When non-native species from other ecosystems are introduced, they can upset that balance and bring harm to the established plants and animals, and the eco system as a whole. They may be harmless and beneficial in their natural environments, but they can totally devastate different ecosystems.
     When non-native species enter into an ecosystem, they can disrupt the natural balance in many ways. They reduce biodiversity, degrade habitats, alternative genetic diversity, via hybridization and introgression. 
     This phenomenon is especially detrimental for rare or endangered species which come into contact with more abundant sub species where the abundant ones can interbreed with them purging the entire rarer gene pool creating hybrids thus driving the entire original purebred native stock to complete extinction. They may also introduce exotic diseases to native species, further jeopardizing endangered plants and animals. 
     Invasive species may be a harmless looking plant or a frog. They don’t have to be vicious looking to bring harm to an area. They may even be beautiful to look at. However when there are no established natural controls such as predators to keep the species in check, there can be a population explosion of the invasive non-native species causing an ecological catastrophe.
     The introduction of non-native species may be accidental or intentional. Many humans want to design their own ecosystems to fit their needs. They bring in ornamental flowering trees, non-native fish, specialty seeds, and exotic animals. Non-native species may arrive in products that were imported from other countries. Many times it is the result of exotic pets which have escaped, or been released into the environment because the owner no longer wanted the responsibility of caring for them. This can wreak havoc on the native species and the established habitat. Just because a species can survive or even flourish in a non-native area, does not mean they should.
     Aside from the obvious detrimental impacts on the ecosystem, there are other serious impacts, economically speaking. Economic costs due to invasive species can be separated into direct costs due to production loss in agriculture and forestry, in addition to management costs of invasive species. Estimated damage and control cost of invasive species can cost more than a billion dollars annually. In addition losses can occur from lost recreational and tourism revenues. Economic costs  when calculated as production loss and management costs, are high, however  if monetary values could be assigned to the extinction of species, loss in biodiversity, and loss of ecosystem services, costs from impacts of invasive species would significantly increase.
     Did you ever think of yourself as an Alien Species? As more and more people spread out to escape the city, taking up residence, out in the country the result is a great deal of construction and pollution, loss of habitat. When we venture out into the wilderness occupied by various wild species we must do our best to respect and preserve the existing environment, lest we become an invasive species.