The House Sparrow is a chunky bird, ranging from 14–18 centimetres (5.5–7.1 in) in length, and from 24–39.5 grams (0.85–1.4 oz) in mass, depending on sex, subspecies, and environment. Females average smaller than males, and southern birds are smaller than their northern counterparts, though altitude may be equally important.Like most of the members of its genus, the House Sparrow is sexually dimorphic. The male's mantle and upper back are a warm brown, broadly streaked with bl
ack, while the lower back, rump and uppertail coverts are a greyish-brown. The crown, cheeks and underparts are pale grey, with black on the throat, upper breast and between the bill and eyes. The bill in summer is blue-black, and the legs are brown. In winter the plumage is dulled by pale edgings, and the bill is yellowish brown. The black throat patch on the males is variable in size, and the size of that patch or badge is correlated with the aggressiveness, suggesting that it is a signal to show dominance in a social situation. The female has no black on head or throat, nor a grey crown; her upperparts are streaked with brown. The juveniles are deeper brown, and the white is replaced by buff; the beak is pink to dull yellow. The House Sparrow is often confused with the smaller and more slender Tree Sparrow, which, however, has a chestnut and not grey crown, two distinct wing bars, and a black patch on each cheek.
All of the House Sparrow's calls are variations on its short and incessant double chirp call note "phillip" or "chirrup" made as a contact call by birds away from their nesting area, or by males as a proclamation of nest ownership or to invite pairing; this call led to the now obsolete folk name of "Phillip Sparrow". House Sparrows give also give this call in what is known as "social singing", while resting between periods of feeding, or while roosting. In the breeding season this call becomes what is called an "ecstatic call", which is similar to a song, as it is uttered by the male at great speed. Aggressive male House Sparrows give a trilled version of their call, transcribed as "chur-chur-r-r-it-it-it-it". This call is also used by females in the breeding season, to establish dominance over males in order to displace them and feed young or incubate eggs. House Sparrows give a nasal alarm call, the basic sound of which is transcribed as "quer". When in great distress, they give a shrill "chree" call. Another House Sparrow vocalisation is what has been described as an "appeasement call," given to inhibit aggression, usually by a mated pair. These vocalisations are not unique to the House Sparrow, but are shared with only minor variations by most sparrows.