Of course you are upset. That's an awful thing to find.

A rat could get up the fire escape but would more than likely carry the baby away. Rats tend to take the head and eat the contents of the crop.
A crow would have carried the babies off too. Maybe a Jay because the babies would have been to heavy for a Jay to carry off. You would have noticed a lot of pecking, tearing kind of wounds.

My guess would be a bird of prey.

Now that whatever killed them knows there is the potential to find food there. They will return.
It's so sad. I'm really sorry.

 

I think you're guesses are right. Iam not sure how to prevent it again as the birds you mentioned are really smart and probalby come back to the nest if they see it has something they want in there.. If the pair use the space again you can give them fake eggs to sit or just take the eggs and nest away and hope they find a different place where they can't be found out by this predator.

 

Thank you both for the replies. Sounds as if there is not much I can do except remove the flowerpot so they do not use the nest again. I harbored a dream that I could still witness another brood live to maturity but would never want to run the risk of the horror of today reoccurring.
If anyone else has any other thoughts or suggestions, I'd appreciate them. This is a wonderful resource and bless you all for your knowledge and caring.

 

"Horror" of mother nature can be pretty gross, ,even with you're background in animal health ,science it must of been pretty disapointing.

 

It could also have been a hawk, if that wasn't already mentioned. Hawks and falcons are present in NYC. A smaller species of these would kill and try to eat at the kill site, as they could not carry off the dead body...

The only thing you could conceivably do would be to build them a safer enclosure, move the pot more out of direct view, etc; but the question becomes whether the Parents would then be scared off. I have somewhat successfully done this in the past, and had it rodent-proofed and to a lesser degree hawk-deterred (something which one can never fully achieve) but it does take some vigilance and effort.

I am sorry to hear this...I hate stories like that, actually.

 

Probably a Peregrine Falcon... they are pretty common there..

 

That would be a good bet if it was a bird of prey....small ones, like pergerines or coopers or sparrowhawks, kill like that.

If the nest was enclosed........e.g. with a "roof" over it.........perhaps a box like structure opened on the side..........perhaps it would be less visible to aerial predators. I would certainly let them try nesting again....it will be a couple of weeks by the time they lay new eggs and the eggs hatch.

Yes. The enclosure idea works very well as far as ground predators go...rats and such. For birds of prey it becomes trickier, because if they have scoped out a place, they will return to visit from time to time. Quite sadly, I learned this the hard way back at my old place in SF

...but there are deterrents one can add in addition to an enclosure or screen/blind which up the odds a bit against a predator bird....

 

If the nest was enclosed........e.g. with a "roof" over it.........perhaps a box like structure opened on the side..........perhaps it would be less visible to aerial predators. I would certainly let them try nesting again....it will be a couple of weeks by the time they lay new eggs and the eggs hatch.