Do Magpies despise starlings & why do they “hide” there kills ?

I have one Magipie in my garden who appears to only despise the starlings as myself , he will swoop at them regularly never injuring them , but moving them away from the food . However, he attacked two fledglings this past week - ensuring they were killed by a bite on the neck. He didn’t eat them,  but tried to hide the bodies in the garden . One was moved behind a planter and another moved and dumped in a shallow bird water dish . 

I swear he tries to hide the bodies  so as not to upset me :)  However , anybody have any bird behavior thoughts on this. 

PS he is leaving the other birds alone ,