Bushtits are tiny, highly social birds found in Oregon, often seen in large, chattering flocks. While they share a generally plain brown and gray plumage, there's a key difference that allows you to tell males and females apart:

Male Bushtits: In Oregon, males have dark eyes. Their heads are typically gray, and they may have brown ear patches.
Female Bushtits: Females in Oregon are distinguished by their pale, yellowish eyes. Like males, their heads are generally gray with brown cheeks.

Bushtits exhibit some geographical variations in coloration. Along the Pacific Coast, including parts of Oregon, they tend to have browner crowns, while those further inland in Oregon will have grayer crowns. However, the eye color remains the most reliable way to differentiate sexes throughout their Oregon range.