That being said, she killed the newborn right in front of her other offspring - is the other one too young to have that imprinted on him/her? or will he/she grow up thinking it's 'normal' to kill one of my kids to feed to the other?
At this stage the chicks' eyes aren't even open so no worries there.
And Terzo may not be that invested in these kids as they aren't his, we've had similar situations here and the new male doesn't hurt the kids but he doesn't feed them or go out of his way to help other than to feed the female and baby sit when he has to. So if he doesn't step up on the feeding - is she going to kill more kids to feed one? I don't know,l know it's nature but I'm not watching that...too hard for me.
The peregrines can't tell if they are "their" chicks or not and it really doesn't play into their maternal/paternal care. Remember, recovery projects relied on the fact that you can add/move chicks from nest to nest and the adults don't change their behaviour toward them. T-Rex when he was less than a year old would feed chicks in a hackbox before they were released and then later after a couple of nests of his own, he took over four eggs belonging to his father. This year it may be that Faith's eggs are not Ty's - the timing is so very tight and she was involved with Hart even after Ty returned. Parenting for peregrines is hardwired and hormonal. Hardwired to respond to cues from mates and chicks. Hormonal to stick to a territory, a mate and eggs/chicks whether they are theirs or not. Does this always apply? It appears to if both adults are at about the same point in the hormonal cycle. However, if a resident male were killed, the interloper male's cycle isn't in sync with a female who is incubating or brooding and male neglect can result or the hardwiring can jumpstart the hormonal or bridge the gap so to speak and the male gets "better" as time goes along.
There are always outliers with any behaviour but they don't define species behaviour, they are just what they are, outliers who's actions (which is different from behaviour) are predictable only to them. Madame was an outlier, she didn't migrate. Why didn't she migrate? Don't know. None of her offspring or her grand-offspring (more than 3/4 of all chicks produced in this province are related to her) have shown any inclination. The only other bird with a (relatively) short migration is not related to her at all. The rest of them migrate pretty much everywhere - east through Florida and west into/through Mexico. Remember Doorly? Know one could figure out why he destroyed the eggs in his first few nests. They were just about to remove him when one of his chicks managed to hatch. After that, all was great. His destruction of the eggs was his outlier action but turns out his parenting behaviour after that first successful hatch was pretty much textbook. So was the destruction really an outlier or did he know something we didn't even in the egg? (As I recall, they never did report if the eggs were viable or not - Hope & Doorly were half-sibs).