Monday 7 September 2020

Sounds in the night

On Tuesday 1st September, as I have been doing since mid-August, I put my Olympus LS-P4 PCM recorder out in the back garden hoping to record some passing waders. The evening was cool and clear with a slack east wind. I started to record at approximately 10pm. The next day I checked my recordings and in an otherwise quiet night I came across a single note nocturnal flight call between 10pm and midnight that I hadn't previously seen. The note appeared as a vertical line running from just below 4KHz to just above 5KHz.

The quality of the recording wasn't great but I felt it warranted closer examination. On the previous Sunday night, as part of The Phil More's Corner Podcast we had interviewed Magnus Robb of The Sound Approach. During our chat, Magnus had mentioned the nocmig pitfall of Song Thrush and Little Bunting. He described how on the sonogram the nocturnal flight call that both species make appears as a vertical line. My thoughts flitted to that discussion and I checked both species on Xeno-canto. Unsurprisingly I was able to rule them both out quite quickly as their nocturnal calls are a higher frequency to what I had recorded. However, I was now thinking Bunting spp. I shared the recording with my good friend Sean Ronayne who has been regularily 'nocmigging' in Catalunya since last autumn Catalan Wildlife. Sean's immediate response was that there was a chance it was an Ortolan but he promised to look into it in more detail as soon as he could. A few days passed and it was Sunday 6th September before he had a chance to really take a proper listen to my recording. His initial thought was that it was 'probably an Ortolan' but because of the quality of the recording it was hard to tell. The possibility of it also being a Yellowhammer was hard to rule out, especially given that I have seen that species within 5 kilometers of my home and they are known to migrate at night also. At the same time, Sean passed the recording on to Magnus Robb. Magnus has significant knowledge and experience of both the daytime and nocturnal calls of Ortolan Bunting (Nocturnal autumn migration in Dorset, England, and southern Portugal). This morning Magnus replied to say 'it sounds like a bona fide Ortolan to me'.
The above article on The Sound Approach website discusses eight different Ortolan Bunting flight calls and Magnus's view is that this is one of the so-called 'trsp' calls but it could in fact have a name of its own. Furthermore, Yellowhammer calls are shorter and have a less audible downward inflection because of that.


I have posted the recording on Xeno-Canto with the caveat that it 'may be an Ortolan Bunting'. I've not submitted the record to the Norfolk Records Committee but I would like to. I appreciate Ortolan Bunting is a description species in Norfolk and this is a recording of a single note nocturnal flight call. I don't know what criteria or parameters are used to assess such records and am trying to find out. However, with a proliferation of birders now 'nocmigging', I expect record committees will soon start to receive more 'nocmig' records for assessment as time goes by. I'm posting this on my blog because I'm aware that there are other birders 'nocmigging' in Norfolk and East Anglia and I would like to give people a 'heads-up' and request them to listen for similar calls this autumn.

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