kingfisher, snipe
鷸 centers on long-billed wading birds: the kingfisher and the snipe. Both are water birds with distinctive long beaks, so the character unites them under that shared visual idea.
鷸 combines 鳥 (bird) with 矞, which likely contributes the sound. The character was created to name specific long-billed water birds.
The right side is 鳥 (bird), and the left side 矞 looks like a long spear-like beak piercing through something. Picture a kingfisher or snipe with that long beak hunting by the water.
For イツ, imagine an itsy-bitsy snipe with a surprisingly long beak: itsy -> イツ, and the tiny bird is a snipe.
sandpiper (any bird of family Scolopacidae, incl. the curlews, godwits, phalaropes, redshanks, ruff, snipes, turnstones, and woodcocks)
long-billed curlew (Numenius americanus)
Wilson's phalarope (Phalaropus tricolor)
wandering tattler (Tringa incana)
whimbrel (Numenius phaeopus)
ruddy turnstone (species of sandpiper, Arenaria interpres)
pied avocet (Recurvirostra avosetta)
Terek sandpiper (Xenus cinereus)
Latham's snipe (Gallinago hardwickii)
Eurasian curlew (Numenius arquata)
black-tailed godwit (species of sandpiper, Limosa limosa)
Eurasian woodcock (Scolopax rusticola)
red phalarope; grey phalarope (Phalaropus lobatus)
common snipe (Gallinago gallinago)
spoon-billed sandpiper (Calidris pygmaea)
ruff; reeve (species of sandpiper, Philomachus pugnax)
red-necked phalarope (Phalaropus lobatus)
common redshank (Tringa totanus)
solitary snipe (Gallinago solitaria)
phalarope (any sandpiper of family Phalaropodidae)