|Sonogram showing 3 Ortolan Bunting calls from the first flyover bird|
I began recording the nocturnal migration (nocmig) of birds in September 2017 after being inspired by the amazing success Simon Gillings was having not far from where I live in suburban Cambridge. The process involves leaving a microphone outside all night to record the calls of migrating birds. Then, using a free software package called Audacity, scrolling through the spectrogram generated by the recording to look for call signatures (this usually takes from 30 mins to an hour). Over the past year the results from this monitoring technique have been very surprising. I was already familiar with mass nocturnal Redwing migration in October/November, but flocks of Common Scoters passing over my garden in March/April – now this was extraordinary!
|My recording equipment: a Panasonic LS-12 recorder with Rode VideoMicro Microphone placed inside a large bubble-wrap lined bucket|
The spring period was in general very good for nocmig; the stand out species recorded being Stone-Curlew, Avocet and the Common Scoters. Migration began to slow in the summer months and thus recording took a short break before continuing from July onwards. The most notable birds recorded in this period were waders and as August approached wader calls were becoming quite a frequent occurrence.
Interestingly Whimbrel turned out to be one of the most common nocturnal migrants in August. In the past I have heard them at night with my own ears but the numbers passing over in the recordings (minimum of 4 groups on 22nd) were very surprising to me – especially as so few are found locally during the day. The diversity of waders was also unexpectedly high, with not only routine species such as Common Sandpiper and Oystercatcher recorded but also unanticipated species like Godwits (in this case it was hard to distinguish between Black-tailed and Bar-tailed). See which wader species you can identify in the compilation of calls below:
Towards the end of August several even more interesting species were recorded; firstly a Sandwich Tern on the night beginning 24th and then Tree Pipits on 23rd and 30th. Then, when processing the recording from the night beginning 28th, a call was heard that set my pulse racing – an apparent series of ‘plik’ calls from an Ortolan Bunting. This species is a well known nocturnal migrant and can be very difficult to observe in the UK - in fact Ortolan Bunting has never been seen in Cambridgeshire. Recent recordings carried out in the south of England have shown that Ortolan Bunting occurrence here is not as irregular as previously thought – but could my recording be one? After checking through the very thorough ‘Things that go plik in the night’ article (see here: https://soundapproach.co.uk/things-go-plik-night-part-one/ ) I was more convinced and opinion from experts was in agreement. It was an Ortolan!
|Ortolan Bunting - taken earlier this year from Plataforma de Gredos, Spain|
Still on a high from the Ortolan Bunting recording of the previous night I began processing the file from the night beginning 29th with great enthusiasm. I had barely got an hour into the recording (time of call 21:31) when I recognised a familiar looking call signature. It can’t be can it? Another one! Expert opinion was again in agreement – another apparent Ortolan Bunting! This time two ‘tew’ type calls.
Nocturnal flight call recording is really producing some surprising results as well as contributing to our understanding of bird migration. It is also generating further questions. Are Ortolan Buntings a regular nocturnal migrant over East Anglia and if so why have none been detected in Cambs before? Was the large scale nocturnal movement of Common Scoter over England this Spring a rare event or does it happen regularly? Hopefully in the coming years more knowledge can be gathered and these questions perhaps answered. To anyone who is interested in bird migration I would certainly recommend taking part in nocmig. If you would like to give it a go starter kits can be purchased cheaply and there is some very helpful information on the subject here: https://nocmig.wordpress.com/
My thanks to Simon Gillings, Magnus Robb, Aat Schaftenaar, Joost van Bruggen et al. for help identifying the Ortolan Bunting calls.