Makes me wonder if some of your injured raptors are going after "road kill" as a train comes through?
actually, that's not a bad assessment. here in chicago pigeons LOVE the el line stations (not sure about the metra-but i assume they populate those as well) however i have never seen a dead pigeon at any stops. maybe they are swooping in to get a kill when the train is coming.....it makes sense. because as the trains come in, the birds on the tracks scatter and would be less apt to notice a falcon streaming in from behind to get them?