How do the upperparts of the Willow Warbler generally compare in colour richness to those of the Chiffchaff?
Answer
The olive tone on the upperparts is often richer or warmer than that found on the Chiffchaff.
The general coloration of the Willow Warbler is dominated by greens and pale washes, giving it a plain appearance. The upperparts, including the back, crown, and wings, are typically a dull olive-green or brownish-green. While lighting conditions and feather wear can influence perception, the typical olive tone associated with *P. trochilus* is often described as being richer or warmer when contrasted side-by-side with the Chiffchaff. This distinction, however, can be easily obscured by poor lighting or heavy feather wear later in the season.
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