Treecreepers

Eurasian Treecreeper (Certhia familiaris)

Eurasian Treecreeper. Photo: Smudge 9000 – Flickr.

Treecreeper is a species which is often heard long before it is seen. Follow the sound, however, and they usually give very nice views, as they creep up the gnarly bark of mature trees, probing for insects as they go.

The most reliable way to find this species is by learning its call. This is a call that I learned as a child, having been told to listen out for a “high-pitched referee’s whistle”, and indeed that is what it sounds like. Also described as a soft series of rippling “srrii” notes, they can be confused for a similar call given by Blackbird. However, the corresponding call by Blackbird is usually given singly, sounding louder and more forceful. Let’s listen to both, beginning with the softer sounding, repeated calls of a Treecreeper:

Next, compare to the louder, more forceful single call from a Blackbird, best heard at approx. 7 seconds:

The song of this species is also very distinctive. Just like the call, it is quite high-pitched and can be confused with very little. There aren’t many birds which sing at this pitch and those that do sound nothing alike. The song is best described as a series of high notes which rapidly descend, like a ping-pong ball bouncing and tumbling down a series of steps, speeding up as it goes, before ending in a sudden upsweep. Willow Warbler can sound superficially similar, but is lower-pitched and doesn’t have the rapidly descending flourish.

This next vocalisation is something rather special. There is very little mentioned about this in the literature and there are just a few recordings online. We discovered this for ourselves by pure accident. An SM4 was deployed in a woodland site which contained several Treecreeper territories. Upon collecting the SM4, a strange Wren-like rattle appeared over several mornings. It was assumed to be an aberrant Wren, but it just didn’t sit well. When it appeared time after time, seemingly from more than one bird, suspicion arose. It was soon noted that it occurred before, during or after Treecreeper vocalisations. A quick search on Xeno-canto revealed this set-list, and the penny dropped. This was in fact a Treecreeper.

The following comments from the set-list give us a clue as to the purpose of this vocalisation:

  • ” Two birds interacting on treetrunk, birds seemed very agitated”
  • ” Interaction / agonistic calls”
  • ” Alarm call of male after playback of song record”

These comments combined with the fact that our recordings occur in response to another bird’s presence and/or vocalisations point to this being either an excited (towards a partner/potential partner) or aggressive/territorial response. But, as the third comment refers to a male giving this call after hearing playback of another male’s song, perhaps it is more likely that this is an aggressive response given in reaction to another male or unwanted individual encroaching its territory.

Listen carefully, as a distantly singing Treecreeper is suddenly cut by a closer Treecreeper which gives the excited/territorial rattle:

Here is another example of an excited/territorial rattle, following on from a series of more typical “sriii” calls. Again, it is evident here that there are at least two birds involved, with the excitement rattle sounding much louder, and cutting overt the more distant “srii” calls.


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