It's the fourth straight year a mating couple has returned to its unusual urban nest on a ledge at the city's science museum.
The male went missing over the weekend, and several eyewitnesses have told the museum and members of the "Franklin Hawkaholics" Facebook page that the male was hit by a car.
The museum has a window webcam for bird lovers to watch the pair raise their young.
There are three young hawks in the nest, leaving the female to do all of the hunting.
Franklin Institute officials say wildlife experts are being consulted about what happens if the job of feeding three babies is too much for the mother. That could involve providing extra food.
