House Sparrow eggs

• Color: whitish to greenish or bluish white, spotted with gray and brown. Markings vary between females and are often heaviest around the wide end; the same female tends to lay a similar pattern every time.
• Size: 20–22 mm long by 14–16 mm wide. For scale, a US quarter is 24.3 mm across, so this egg is roughly the width of a US quarter.
• Where you find it: messy grass nest in any cavity, including nest boxes. House sparrows do not normally use nest boxes.
• Clutch: 4–6 eggs. A nest with far more eggs than this may hold eggs from two females, or a cowbird egg laid by a brood parasite.

These species lay eggs in the same color group, sorted by how close they are in length. Size and nest site usually settle it.

Laying starts earliest in Alabama (Mar) and latest in Alberta (May). Months are estimates from regional breeding data shifted for latitude.

Eggs hatch after 10–14 days and the young leave 14 days later. See the full baby House Sparrow guide for nestling stages and what to do if you find one on the ground.

• Leave them. Parents often step away for long stretches, especially before the full clutch is laid, because most songbirds do not start incubating until the last or second-to-last egg.
• A single egg on the ground is usually lost for good. Eggs cannot be hatched at home, and possession of native bird eggs is illegal without a permit.
• If a nest is somewhere inconvenient, wait it out. Most small songbirds are done in three to five weeks.
• Watch from a distance and keep pets indoors. Repeated visits can lead predators to the nest.