Young one of Owl is Owlet : General English

Antelope – calf
Bear – cub
Beasts of prey – whelp
Beaver – kit
Birds - fledgling, nestling
Cat – kitten
Codfish - codling, sprat
Cow – calf
Deer - fawn, yearling
Dog - pup, puppy
Duck – duckling
Eagle – eaglet
Eel – elver
Elephant – calf
Elephant seal – weaner
Fish – fry
Fowl - chick, chicken
Fox - cub, pup
Frog - polliwog, tadpole
Goat – kid
Goose – gosling
Grouse – cheeper
Guinea fowl – keet
Hawk – eyas
Hen – pullet
Hippo – calf
Horse - foal, yearling, or
colt (male), filly (female)
Kangaroo – joey
Lion – cub
Owl – owlet
Partridge – cheeper
Pig - piglet, shoat, farrow,
suckling
Pigeon - squab, squeaker
Quail – cheeper
Rabbit - bunny, kit
Rat – pup
Rhino – calf
Rooster – cockerel
Salmon - parr, smolt, grilse
Seal – pup
Shark – cub
Sheep - lamb, lambkins
Swan – cygnet
Tiger - cub, whelp
Turkey – poult
Whale – calf
Zebra - foal