the goat the eagle carried away, dont look much smaller than that deer in the post,? suppose they eat what they want 1st, then carry only the amount m,eat to the nest they need if young there .?
carrying its limit by the looks,enough to hold it and glide down to the ledge,not sure it would be able to gain height if it needed,like you say may well eat their fill first im no expert just a guess cheers