It's looking more and more like only one egg out of three hatched at Washington Square Park. I was at the nest this afternoon and through the twigs could see only one eyass eating (around the 2:30 mark on the video).
One of the lesser known issues with rodenticides is their effect on fertility in raptors. We might be witnessing this here. While the Parks Department has stopped using poisons in Washington Square Park, they are commonly used by NYU properties around the area.