Aggressive female blackbird

Hello. We have a female blackbird who is constantly visiting our garden. She is very very vocal. She has now started to stand her ground with our cats who are now reluctant to go outside! She has also dive bombed a visiting friend and my partner on separate occasions. I love seeing her looking for worms etc and presume she has chicks to feed. She is getting very brave and was right outside our back door yesterday even with two cats And two dogs living here! I was just wondering if this was normal behavior as I’ve never come across it before. I’m also a bit worried she may get caught by a cat soon as she is very defiant!