We note that each feeder contains a card name, which allows us to order them:
SOFTENUP
JACKALDOGHYBRID
BEAUTYQUEEN
THELIONKING
FLYINGACE
Looking at these feeders really, really hard allows you to realize that they are 54 characters long in total (i.e, “you write a letter on each of their backs”).
We can match these 54 characters up with the cards (in order) of an unopened 54-card deck of Bicycle® index cards.
And taking the letters corresponding to the cards presented on the puzzle yields our answer, ROYAL FLUKE.