The house cats are not native to the ecosystem of North America and as such
when outdoors they pose a real threat to the many migratory birds that are
endangered. It is natural for these cats to hunt, hungry or not, and their
introduction in the 19th century for pest control has had a negative impact
on these migratory species. <A HREF="http://www.birdsource.org/birdcast/index.html">BirdCast</A> is a site where this is explained as
well as being one where you can participate in ornithologic radar
developments.