Eurasian tree sparrow
The russet sparrow's breeding season is short, lasting about three months. The Himalayan subspecies "cinnamomeus" has been recorded breeding from April to August, the nominate subspecies breeds from May to July, and the subspecies "intensior" is believed to breed in March. During its breeding season, the russet sparrow is not gregarious, and its nests are dispersed uniformly rather than clustered. Its nests are most frequently built in tree cavities, often disused woodpecker nests. The russet sparrow has been recorded breeding alongside the Eurasian tree sparrow and white wagtail in black kite nests, taking advantage of the territorial defence of the kites to avoid nest predation. Other nest locations include the eaves of thatched roofs, stone walls and embankments, and electric junction boxes. In Bhutan, it nests in holes in the outer walls of monasteries, often alongside the Eurasian tree sparrow. In Sakhalin, it will sometimes build free-standing nests in bushes. The russet sparrow also uses the disused nests of the red-rumped swallow, and a pair of russet sparrows has been recorded attempting to oust a pair of black-crested tits from their nest.