Willow Warblers are a passage migrant through Portugal, normally seen on the autumn migration rather than the Spring. It is one of the most numerous species in the Western Palearctic with an estimated 30 - 60 million pairs in Europe alone.

They are told apart from the very similar Chiffchaff by song and also leg colour, those of the Willow Warbler being pale and those of the Chiffchaff being dark.

Willow Warbler (Phylloscopus trochilus)

There's a one month window when they seem to be on every shrub, tree and piece of grass.

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Over-wintering south of the Sahara, they feed up on the late hatching insects in the Alentejo as they move south during September and October.

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Found most often during the Autumn migration when massive numbers move through Portugal.

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