Willow Warbler or Chiffchaff?

In a hedgerow in Caithness, Scotland and vocal!

  • Chiffchaffs barely sing. They just have a very monotonous call, one note repeated ad infinitum. As you say this was vocal, I presume you mean actual singing. That's the most reliable way to separate a Willow Warbler from a Chiffchaff. It's very, very difficult to do it visually. However, you have a third option. It's a Sedge Warbler. The face markings and pale stripe is too strong for either Willow Warbler or Chiffchaff.