wgeoff

An Arctic Warbler was making a double note call near the upper school building on Po Toi today.
Double-note calls are quite common in spring so this in itself was not unusual. However, the call sounded a bit different so I recorded it, part is here

http://www.geoffwelch46.com/AWCALLGW.mp3

The sonogram looks like this



This looks more like the sonogram of the call of examinandus (middle row right hand side) than either borealis or xanthodryas in this page from the Per Alstrom paper on the three species



I mention this because the HKBWS Trip to Po Toi is tomorrow. The bird itself looks like this



[ Last edited by wgeoff at 4/05/2013 08:36 ]

JamesLambo

Hi Geoff

We all saw lots of Arctic Warblers today, but they were generally quiet. At least one seen was very yellowish on throat and belly, but I don't know if anyone got good photos of it. Abdel and I heard two different ones calling, but could not agree whether their calls were the same or different ... so I am afraid we cannot be of much help here.

As for the sonograms. Although the call you recorded looks more similar to examinandus than to the others, it still doesn't really resemble it very well, as far as I can see. For instance, the pitch range you recorded starts at 1.5 kHz and extends up to 7.5 kHz, whereas PA's examinandus from 3 to 6.5. And the two parts of the call do not overlap in pitch. Also, the timing doesn't match very well, with PA's example being more regular. I don't know if these are significant factors, just saying.

James

wgeoff

Thanks James

The blobs below 4.5kHz on the sonogram are another bird calling (Chinese Bulbul I think) which does not appear in the shortened extract of the call I have given. So the Arctic Warbler is just the two lines between 4.5kHz and 7.5kHz and is very regular. I think it matches the right hand PA examinandus quite well but I'm not saying it is examinandus - there's lots of wriggle room here.

cgeoff

Following on from the discussion above regarding the identity of vocalising 'Arctic Warblers' in HK, this morning I recorded at Pak Sha O both song and call of Phylloscopus borealis from the same bird. Two of the sonagrams show different song phrases, and the third illustrates the call. I have identified this bird as borealis on the basis of the following:

2-3 elements in each syllable
repetition of the same syllable, with no others interspersed (i.e. AAAA)
the very similar pitch of each syllable, with no obvious change in the final element
call: peak frequency around 6000hz, covering a relatively narrow range ('peak' here doesn't mean the highest, but frequency that is 'strongest').

The rather simple composition of each syllable indicates borealis, rather than kennicotti.

GeoffC

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borealis song call.mp3 (162.75 KB)
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[ Last edited by cgeoff at 3/05/2014 16:11 ]