Female Parakeet Killing Male Parakeet

I've had a female and male parakeet for quite some time now. About 4 weeks ago my parakeet had two babys. This is the first time they've had babys. I went grocery shopping today and when I came back I found the male bird laying on the bottom of the cage dead. I picked him up with some gloves and examined him. His head was bloody and so was an area under his left wing. After I examined the bird I looked in the cage and noticed alot of blood on the pole they stand on, the food cup, and the female birds feathers. The baby birds were unharmed.
My birds have never fought before. Im thinking that it may have had something to do with the baby birds. Could someone tell me why this happened?

 

Hi I am sorry for whats happend.
Parakeets are very aggressive during breeding and raising chicks.
The problem is that these birds may not have bonded together very well as they usualy make good parents, Your female may have seen the male as a threat and that s why she has killed him.

Its unlikely she will harm her chicks but i would advice never to breed from her again as these traits get passed onto her offspring.

How old where both birds and how long where they together before allowing them to start breeding?

Mike