It is amazing to think even a small bird such as this Song Sparrow is light enough that it can perch on a leaf of a milkweed plant. This bird was busy bring food to a well hidden nest somewhere nearby and would stop and scout the area before disappearing into the scrub. I did not want to disturb the nest so I stayed a distance away. Always use caution in these circumstances because many bird species nest on or very near the ground and nests can easily be stepped on. When you see where these nests are hidden, it's a bit sad to realize many are destroyed by roadside mowing and first crop field cutting.
Mostly insects and seeds. Eats many insects, especially in summer, including beetles, grasshoppers, caterpillars, ants, wasps, and many others, also spiders. Feeds heavily on seeds, especially in winter, mainly those of grasses and weeds. Birds in coastal marshes and on islands also feed on small crustaceans and mollusks, perhaps rarely on small fish.
Males often defend only small nesting territories, so high densities of Song Sparrows may be present in good habitat. In courtship, male may chase female; may perform fluttering flight among the bushes with neck outstretched and head held high. Nest site varies, usually on ground under clump of grass or shrub, or less than 4' above the ground, sometimes up to 10' or higher. Raised sites may be in shrubs, low trees, or marsh vegetation, often above water. Rarely nests in cavities in trees. Nest (built mostly or entirely by female) is an open cup of weeds, grass, leaves, strips of bark, lined with fine grass, rootlets, animal hair.