The "-ling" refers to the baby of the animal...mainly birds I think? It's an actual noun, sometimes an adjective, but not a gerund nor continuous verb form. Duck - duckling Goose - gosling Hatchling (ie. the baby which has just hatched out of the egg) Fledgling (ie. the young bird, about to try flying for the first time) Compare these with the actual "-ing" forms of related verbs: ducking, goosing, hatching, fledging. Don't use "fledging"; people will think you mean "fledgling". Even Google asked me that just now.

"fledge" is a VERB that means 'feed, care for, and rear young birds for flight.' while "fledgling" could either be an ADJECTIVE or NOUN (search the meaning in the dictionary for yourself). don't be confused with the "-ing" form of 'verb continuous tenses', as it doesn't always mean that a word ending "-ing" always is a verb. :)

"Fledgling"is a noun, it is not a gerund verb. Fledgling = offspring

It's just the way it is.