Turns out this photo was taken only two days before this individual died. Also turns out this was the zoo's last Forster's, though they still have a CommonXForster's left.
Only took you until now, and Semioptera has been gone for years but for the record - Forster's has a longer and more gracile beak and a more pronounced black tip to said beak. In Common the tip is just a hint or sometimes entirely absent.
@TeaLovingDave yeah but I still figured it'd be good to document on the photo
I had no reason to assume Bronx's were anything other than Forster's because all the animals I photographed in 2013 and 2014 happened to be the Forster's and the zoo removed the signage for Common but kept the signage for Forster's for some reason.