A respected Polish scientific institute has classified domestic cats as an "invasive alien species," citing the damage they cause to birds and other wildlife. Institute biologists were surprised by the negative response when it added cats as the 1,787th entry on their list of invasive species. They described a growing scientific consensus that domestic cats have a harmful impact on biodiversity, given the number of birds and mammals they hunt and kill. But, the institute stressed that it did not propose any program to euthanize cats and said it was "opposed to any cruelty towards animals."
Class discussion: What is an "invasive alien species"? Can cats harm biodiversity? How about dogs? Why were they domesticated? Which animal species has caused the vast majority of extinctions among other species? Domestic dogs and cats are very effective hunters. Is that why they are the most common animal companions to human beings? How have humanity’s domesticated species – dogs, cats, cattle, sheep, poultry, wheat, corn, rice, etc. – changed the natural world? Is there any place on Earth that has not been changed by the activity of Homo sapiens, a relatively recent species?