They build large nests relative to size which function as the center of all activity. They prefer small enclosed places such as house shutters, drainage piping, building rafters and corrugated metal siding. They will build a spherical nest in a tree or another exposed place if they have no other option. The building material will be sticks, with an inside lining of grass, string, fabrics or straw. The nest will often hold several families. House sparrows only mate for a season. They average three broods per mating season with each brood containing four to seven eggs with 20 offspring a year average. Egg coloration

will be white, pale blue or pale green with a few gray or brown dots. If unchecked, a breeding pair can grow to over 2,000 birds in two to three years. House Sparrows are not migratory, but in cold climates can show movement between rural/suburban breeding sites and warmer winter roosting sites in the city. House Sparrows are aggressive birds and will often force out other birds from their territories. They are flocking birds and will gather in the thousands to take over feeding and roosting areas.