When walking to classes around the physics and math buildings, I found something unique to that part of campus: a birdy bloodbath. No matter when I went, blue jays and robins would be in pieces around the courtyard, feathers and wings scattered around the cobblestone. For a while, this was a mystery to me: what about this particular part of campus made birds meet their doom? I hypothesized that some predator might be lurking where I couldn’t see, picking off the birds one by one. But that made me wonder: what was it about that spot? A cobblestone courtyard wasn’t the easiest place for prey to hide, but it also made predators easier to see as well. Thus, I developed a hypothesis that the predator must be avian in nature– if they swooped down from the sky, the lack of cover wouldn’t bother them as much as terrestrial prey.
To test this hypothesis, I examined a variety of feathers I found around the courtyard. Some were downy, some were ripped directly from abandoned wings, and some were long flight feathers shed by various birds. I identified a variety of species via close examination of their feathers: robins, sparrows, and most surprisingly, shorebirds like Dowitchers (which is often prey for a particular bird species soon to be mentioned). This, along with another peculiarly patterned feather, led me to my discovery: the mystery predator spreading mayhem across campus was a peregrine falcon. 
It is likely that the falcon was able to take advantage of a niche offered by the courtyard. The wide open expanse left prey exposed, but was too barren for any terrestrial predators to sneak up on the birds. The avian peregrine was adapted well for this type of environment, bombing down on birds that made the mistake of flying near their territory. This type of niche differentiation, in which animals fill a roll offered by their environment, is known as the concept of a “Grenellian niche”. It seems that the peregrine falcon was able to fill this urban courtyard niche, finding a home near the math building– and a very feathery feast. I conducted this project as part of Professor Pringle’s EEB321 class at Princeton University.