The ducks have deployed dogs as pacification tools to keep the nuns compliant with their horrible deeds. As usual, the hero child can see right through the dæmons ruse; hence why the ducks are gesturing to the other kids to lie on top of her in an attempt to smother her to death. I wonder why they don't just kill her; but maybe they need the kids to live before they harvest them for adrenochrome or some other nefarious goal.
The seemingly-idyllic scene is contrasted by the pigeons looking from the shadows. One stoically looks on the situation, as if it knows the grim fate those humans will encounter. The other, less calm and collected, suffers and epileptic seizure from contemplating what horrors await the kids. A sinister breeze blows the leaves away from the trees, representing the lives of the kids taken by the ducks, as leaves by a summer breeze. Hidden in plain sight. Psychological horror at its finest.
Notice a duck has a beret. It's either French (evil, self-explanatory) or Basque (terrorist). It's a message: if that duck is happy that the dogs are there, the dogs aren't there for a good reason. Of course the older nun is completely gone. She's been brainwashed for a longer time. Troubling. Concerning. I didn't think the last thing I saw before going to bed was going to be this disturbing picture. Thanks, pal.