Sparrow

A word that covers two unrelated families

In English, “sparrow” loosely covers two distinct bird families:

• Old World sparrows (Passeridae) — the house sparrow, tree sparrow, etc. Originally Eurasian and African.
• New World sparrows (Passerellidae) — song sparrow, white-throated sparrow, fox sparrow, etc. American natives.

The two groups evolved separately and aren’t closely related, despite the similar size and brown coloration that gave them the shared common name.

House sparrow’s global reach

The house sparrow (Passer domesticus) is one of the most widespread birds on Earth — found across Europe, Asia, Africa, the Americas (introduced 1850s, New York City), Australia, and many remote islands.

Its success is tied entirely to human settlements. House sparrows:

• Nest in human structures (eaves, vents, cavity nests in walls)
• Eat human food waste, spilled grain, and bird-feeder seed
• Tolerate noise, pollution, crowding
• Don’t migrate; stay year-round wherever humans do

Where humans abandon a settlement, house sparrows often disappear within decades.

A current decline

Despite global ubiquity, house sparrows are declining sharply in many parts of their original European range — UK populations down 60–70% since 1980. The cause isn’t fully understood but likely involves:

• Cleaner agriculture (less spilled grain)
• Modernized buildings (fewer nest cavities)
• Pesticide use (reducing insect food for chicks)
• Predation by domestic cats

The British “decline of the house sparrow” has been a celebrated environmental concern for decades.

Native New World sparrows

The American “sparrows” are entirely separate species from the introduced house sparrow:

• Song sparrow — well-known singer, regional dialects.
• White-throated sparrow — distinctive whistled song “Old Sam Peabody.”
• Fox sparrow — large, rufous, ground-foraging.
• Chipping sparrow — small, neat, with rusty cap.

A naturalist with a local field guide can distinguish a dozen sparrow species visually. The undifferentiated “sparrow” of common parlance hides a remarkable diversity.