- Short note: it's possible to identify vagrant Iberian Chiffchaffs based on calls
- Well described in the past, but not necessarily widely used in the field

Figure 1. Iberian Chiffchaff, The Hague, the Netherlands, April 2016: this singing bird also called frequently.

In April 2017 I was lucky enough to find a calling Iberian Chiffchaff (Phylloscopus ibericus) on Texel. I was a bit hesitant to report it immediately as a certain Iberian, also because I couldn't get a proper view (it was on private property), but fortunately it started singing later. What I learnt was that I should have trusted the call in the first place!  

I was even more lucky when I was able to test this when I found yet another calling bird in The Hague shortly after, in July 2017. This bird never sang. This was only the 2nd Dutch record of a bird that only called. I do not mention this to show who's the alpha male monkey here, but rather the opposite: if I can do it, many birders can. In fact, it's not even hard to learn the differences for any reasonably experienced birder. It's easier than the difference between the calls of Common Chiffchaff (Ph. collybita) and Willow Warbler (Ph. trochilus)! We must be missing non-territorial and female birds now, and perhaps we're missing out on autumn records.

The striking differences in calls between several chiffchaffs sensu lato have been well described in the past, yet in Iberian it's not necessarily a feature widely used by birders in the field. Their calls however are considered diagnostic – even in the narrow contact zone with Common Chiffchaff Ph. collybita where hybridisation takes place (however note that calls of hybrids are not described).

Iberian Chiffchaff has a somewhat melancholic, downward inflected 'chyeeee' call. According to some birders, their calls vaguely recall a Siskin, or Bullfinch – species no one associates with Common Chiffchaff!

Figure 2. Iberian Chiffchaff, moulting adult, The Hague, the Netherlands, 15 July 2017. This bird was identified by its call. This was the 3rd record for the city (Gerjon Gelling)

Here are some typical calls of an Iberian Chiffchaff  (The Hague, the Netherlands, 14 July 2017)

Compare this to the call of this juvenile Chiffchaff, recorded on the same day and the same place

And adult bird giving 'sweet' and 'sweeo' calls, Malvern, UK, april 2017 (Andy Warr/ XC364424)

The 'peeep' of Siberian Chiffchaff (Ph. (collybita) tristis) also sounds sad, but it's a flat, not a downward inflected call and it's slightly lower pitched. This call is from September 2016, Cheboksary, Russia (Albert Lastukhin/ XC336654)

The differences are also visible in the sonagrams:

1. Iberian Chiffchaff. Note how the pitch drops, from more than 5kHZ to below 4kHz.

2. Siberian Chiffchaff starts at a slightly lower pitch and is almost flat, dropping about 0,5 kHz.

3. The juvenile call of Common Chiffchaff first rises and than drops, which is well visible in the sonagram

Figure 3. Sonagrams of Iberian (upper), Siberian (centre) and Common Chiffchaff (bottom)

The well-known "hueet" call from Common Chiffchaff is also strikingly different (The Hague, August 2017):

This is an upward inflicted call, so it's not surprising that the sonagram more or less mirrors that of Iberian. Note that  it starts well below 3kHz and ends above 4 kHz.

Figure 4. The sonagram of the hueet call from Common Chiffchaff  more or less mirrors the call of Iberian Chiffchaff

Of course Chiffchaffs produce different calls, and there's some variation in Iberian, too, but no Chiffchaff sounds like the calls above. Now let's all go out and find that autumn bird!


Here's another Iberian, from Texel, April 2017 as a final reminder: