Identifying Chiffchaff & Willow Warbler

Chiffchaffs and Willow Warblers are two birds that most new birders struggle with. 

They are both phylloscopus warblers, which means they are in the same family as each other and as so look very alike. They are both small birds with slender legs and bill. They both show greyish green and white plumage with no striking features. Identification isn't helped by the fact that they are both very lively birds; constantly on the move, flicking through the foliage in search of flies and insects. 

However with a little time and effort you will get to know these birds and I guarantee that if you put the time in now, you will have no problem identifying these birds in the future. There are a few key features to look for and the main ones are as follows...

1. LEG COLOUR is probably the easiest way of telling Chiffchaff from Willow Warbler. However it is not foolproof but it is generally a good guide line. Chiffchaffs have black legs and Willow Warblers have light brown, flesh coloured legs. The problem with this feature is that Willow Warbler leg colour can sometimes vary and birds with dark legs have been seen but this is the rare exception to the rule. 
   
2. SONGS & CALLS. The songs of these birds could not be more different and are well worth learning. Chiffchaff is a very easy song to remember as the bird simply says its name over and over again. A loud chiff-chaff, chiff-chaff, chiff-chaff. The call is a loud "hweet".  Willow Warblers have a very fluid like song consisting of descending notes and once learned is easy to remember. Call is a loud "hoo-eet". 
   
3. HABITAT. Although both warblers are ground nesters, Chiffchaff's tend to inhabit taller stands of deciduous trees and woodland. Willow Warblers can be found in a variety of habitat, from parks and gardens to hedges and willow copses. While on passage in spring and autumn both warblers can be found virtually anywhere. 
   
4. PRIMARY PROJECTION. If you ask any experienced birder how to tell Willow Warbler from Chiffchaff, they will tell you that primary projection is the proper way to do it and as so it's worth explaining. It's not as hard as it sounds but it does requires a basic knowledge of bird topography, in particular the different groups of wing feathers and where they are situated. Basically it is the length that the primaries extend past the tertials and how this relates to the tertial length e.g. in the figure below the primary feather projection is only half the length of the tertials in Chiffchaffs. Whereas in Willow Warblers the primary projection is equal to the length of the tertials. This also indicates that Willow Warblers travel further on migration. All the way to tropical Africa compared to Chiffchaff which winters in the Mediterranean.

Now for the test!  Can you tell what these two birds are? 

Answers are ………

Chiffchaff on the left and Willow Warbler on the right