Botteri's Sparrow

The Botteri's Sparrow is a large, plain-plumaged sparrow of dense native grassland, occurring in the United States in two widely separated pockets: southeastern Arizona and the coastal prairies of southern Texas. It closely resembles the related Cassin's Sparrow but differs in structure, habitat preference, and especially voice.

Plumage is understated: brownish and streaked above, with plain, unstreaked buffy underparts. The bird has a notably large bill and a long, somewhat rounded tail, giving it a bulkier appearance than many grassland sparrows. Its plain face lacks strong markings, making the song the best tool for confident identification.

Botteri's Sparrow is closely tied to tall, dense grass, often with scattered shrubs, and can be difficult to see well as it tends to stay low and hidden except when singing from an elevated perch.

Key Field Marks

• Large size and bulky build for a grassland sparrow
• Large, heavy bill
• Plain, unstreaked buffy underparts
• Streaked brownish back
• Long, rounded tail

Similar Species

• Cassin's Sparrow: similar plain plumage but smaller-billed and plainer-faced, with a distinctive fluttering skylarking flight song rather than the accelerating trill of Botteri's Sparrow

The song is the most reliable identification feature: an accelerating series of chip notes that rolls into a rapid trill, often compared to the sound of a ball bouncing to a stop.

In the United States, Botteri's Sparrow occurs in two disjunct areas: dense sacaton and other tall bunchgrass grasslands of southeastern Arizona, and coastal prairie grasslands of southern Texas. The species also occurs more broadly through Mexico and into Central America.

It favors relatively tall, dense native grass, sometimes with scattered mesquite or other shrubs, and is sensitive to overgrazing and conversion of native grassland, which can reduce the structural density it requires for nesting and singing perches.

Behavior

Botteri's Sparrow tends to stay low and hidden within dense grass, foraging on the ground, and becomes most visible when males sing from an exposed low perch such as a shrub or tall grass stem.

Voice

The song begins with a few slow chip notes that steadily accelerate into a rapid trill, often described as sounding like a bouncing ball coming to a stop.

Feeding

Diet consists of insects and seeds gathered from the ground and dense grass cover.

Nesting and Breeding

Nests are built on or near the ground within dense grass, well concealed from view. Clutches typically contain 3-4 pale, unmarked eggs.