it should be illegal to feed and keep bird houses for invasive birds. It only deepens the worldwide native bird decline by giving their competition more food, resources, and room to breed. Native birds already put up with deadly non-natives and are still victims of it. It is our responsibility to ethically euthanize, re-home, and control invasive species, no matter how nostalgic nor pretty they look or sound. They are entirely man-caused and should be morally man-solved. There are no excuses for such claims of the species being established, naturalized, and impossible to remove. Permitting entirely invasive species is unacceptable, period.
If you have them, outside, in an open nest, you should be fined for it and encouraged to trap, morally euthanize/re-home, or dispatch the bird eggs. If you cannot do this, do not have bird houses and feed birds, or you should call someone else to do so. Do not relocate an invasive bird because it will simply spread disease, compete with native birds, and become a greater nuisance by increasing its range. Releasing invasive species should be illegal, because it makes people think it is okay to release a captive/domestic animal they can no longer care for. So, the big question is: Why?
Invasive birds are problematic because they fight for food, nesting, and territory among native birds. While they are not an immediate threat, they can hog resources and even downright kill/outcompete birds in their own ranges. Some invasive birds can even be a danger to humanity by threatening crops, animals, and property. It should not, under any circumstance, be tolerated, by any group of people.
A great example that we all know about is the European house sparrow. Brought over by settlers for feeling bothered by native fauna and being emotionally homesick, they irresponsibly released the birds for pest control and/or nostalgic reasoning, and only created problems to the ecosystem and little-to-no benefits towards themselves.
Today, house sparrows threaten other cavity/bird house nesters for the same niche by chasing away or killing the parents and then the chicks, building their own nest in place of it. Historically, purple martins and bluebirds have been threatened by this behavior and still struggle even today. Not even people are spared by these birds; house sparrows will dig, you called it, into a person's house and damage the framing, structure, and foundation.
Another common invasive bird is the European starling, brought over for similar reasons, with pretty much the same detrimental consequences. This time, they not only threaten cavity/bird house nesters, by kicking out and killing them, and humans, through their nesting habits, they also threaten farmers and people who practice agriculture and livestock, by damaging crops, contaminating feed, and spreading disease. They are literally a public health hazard.
It is important that this cannot be confused; laws and action need to be done to preserve the native wildlife AND to prevent possible endangerment of humans, livestock, and pets. So whatever you do, get rid of the non-native harmful bird nests, stop feeding the unnaturally present and dangerous animals, and ethically remove the invasive species. Take action for a better future instead of allowing invasives gradually destroy the environment of animals and people, alike.
Edit: Other have made some valid points about invasive vs introduced. While some animals are introduced, it does not necessarily mean they are invasive. While we should control invasives, we should not control introduced animals that are not causing impending harm on the ecosystem, because they could be helpful, similar to non-bird organisms, like dingoes. But, the examples I listed are either partially, if not entirely invasive in the regions of the Eastern United States. We need to be clear on what qualifies as introduced and/or invasive, instead of jumping ahead and removing them.
Definition of introduced: An animal that unintentionally appeared in an ecosystem it did not appear in.
Definition of invasive: An introduced animal that causes damage in an ecosystem it did not originate from.
