The Franklin Institute in Philadelphia, where the hawk made her nest on a window ledge, set up a webcam feed for enthusiasts to observe the hawk, dubbed "Mom" by fans. When the bird laid her first egg Monday, observers said she was on track to lay another egg Thursday and a third on Sunday, a prediction that came true, the Philadelphia Inquirer reported Monday.
Hawk watchers said the past three springs have seen Mom lay three eggs, each spaced three days apart.
The observers said Mom's former mate, "Dad," was killed by a truck in the spring, and the watchers were shocked when another male hawk came into the picture and took up the father's role.
"All of us who know red-tailed hawks just marveled at that. There's been no recorded case of all that; it's brand new," said John Blakeman, a retired master falconer and biology teacher in Huron, Ohio. "Usually that's in the off-season. What's brand new is a floater coming in to take up the duties of a deceased tiercel, or father, who is providing all the food during the early incubation."
Blakeman said the eggs will hatch in about a month.