Most predators are not too selective in choosing their prey and great blue herons fall into this category. I watched a mother duck swimming in a small pond with 2 ducklings in tow. I knew this is a very low number for clutch size so I assumed some predator was involved. As I looked around I could see a great blue heron hiding motionless along the shore. As soon as the duckling swam into striking range it became food and then there was only one.