sparrow
雀 centers on the small, lively bird: a sparrow. The character itself visually suggests a small bird with a compact body and short tail.
雀 combines 小 (small) with 隹 (short-tailed bird), together suggesting a small bird, i.e., a sparrow.
The top 小 means small, and the bottom 隹 is a bird with a short tail. Picture a tiny, chirpy sparrow: small bird = 雀.
For ジャク, imagine a sparrow landing on a jack-o'-lantern: jack -> ジャク, and the small bird pecks at the pumpkin.
mahjong; mah-jongg
tree sparrow (Passer montanus)
peafowl (incl. the male peacock, female peahen, and young peachick)
Vermilion Bird (god said to rule over the southern heavens)
canary (esp. the island canary, Serinus canaria)
skylark (Alauda arvensis)
Japanese tit (Parus minor); Oriental tit
black-capped chickadee (Parus atricapillus)
Indian peafowl (Pavo cristatus); common peafowl; blue peafowl
Carolina chickadee (Parus carolinensis)
three-player mahjong; sanma
whitetail dascyllus (Dascyllus aruanus); humbug dascyllus; banded dascyllus; white-tailed damselfish
Adiantum edgeworthii (species of maidenhair fern)
Eurasian nuthatch (Sitta europaea)
gossipy Kyotoite
russet sparrow (Passer rutilans); cinnamon sparrow
Japanese murrelet (Synthliboramphus wumizusume); crested murrelet
willow tit (Parus montanus)
Aleutian Canada goose (Branta canadensis leucopareia)
stout chromis (Chromis chrysura)