Source on that? Most kids don't make a habit of killing local wildlife. Or are you using "kids" as a proxy for "habitat loss from rising human population"?
I'm including indirect kills over their lifetime, not just direct kills over the childhood (kittens aren't capable of killing that much either), but otherwise, it's a fairly 1:1 comparison, nothing to do with whether the human population is rising or not.
Anything that we consume and whose production method kills some number of birds. The number is immense, and it includes all kinds of stuff that most people do, particularly those in wealthier areas of the world.