The Baffling World of Nocturnal Migration

I am now eight days into my NocMigging adventure. Well nine days but the recorder didn't work properly on the first night. Or the third. So I am seven nights of recording in and it has been a revelation. So far I have recorded nocturnal flight calls of 20 species of which Mallard is the most regularly recorded with 1-2 flights per hour. These come with the caveat that many birds are breeding in the drains surrounding the house. I 'think' I had some migrant birds on a couple of occasions but from 68 records it is hard to be sure. In addition I have recorded duck sp. on 26 occasions which all bar one record I think refer to uncalling Mallard where all you can hear is the wing beat. I am a touch unsure whether my Oystercatcher and Curlew records contain migrants. As with Mallard there are records which sound like they are birds heading over at height but Curlew is a nightly occurance as a pair breed in the field adjacent to the house and there is at least one additional pair on Nafferton Carrs. I'm also pretty sure that of the five records of Oystercatcher, most refer to a pair in the village somewhere.

Little Ringed Plover Sonogram

Birds I am more sure are migrants are the rest of the wildfowl with a single records of Gadwall https://www.xeno-canto.org/544393, two records of Wigeon https://www.xeno-canto.org/542038 and Teal and five (!) records of Common Scoter despite missing the big movement (well I sat in the garden and listened live). My first Grey Heron went over in the small hours last night which may be a migrant but may also be associated with the heronry on Nafferton Carrs. Perhaps the most surprising thing has been the occurrence of rallids. Moorhen https://www.xeno-canto.org/542048 is the third most commonly recorded species with 13 records in 7 nights whilst both Coot and Water Rail https://www.xeno-canto.org/544396 have been recorded on three occasions each. Moorhen breeds widely nearby and the calls are sometimes extended so I suspect birds are displaying and there is some territorial stuff going on but doubtless some birds are migrants too.

I discussed two species of wader in the first paragraph but three species are unequivocal migrants, Little Ringed Plover https://www.xeno-canto.org/542564 , Golden Plover, and Snipe https://www.xeno-canto.org/543392 . A single record of the first was recorded in flight calling nine times giving a perfect doppler as it passed over on 6th April. I have managed six records of Golden Plover and a couple of Snipe. When it comes to passerines there hasn't been a perfusion with winter thrushes dominating. Redwing https://www.xeno-canto.org/542035 has been recorded on 14 occasions to make it the second most regularly recorded species with each record consisting typically of a single descending seep call. There have been single records of Fieldfare and Song Thrush chuckling and tsiking respectively as they head home to Scandinavia and beyond. The only other passerine I have recorded seemingly on migration was Blackcap but this one had finished its jaunt, seemingly pitching in at 01:55 on 11th April and singing a single phrase. I saw it holding territory in the morning and subsequently it sings odd single phrases overnight.

I am also getting a handle on the breeding and resident birds and there is a certain pattern to the way they occur. I set the recorder for civil dusk as per the NocMig protocol and in theory record until civil dawn. I say in theory because most of the time the rechargeable batteries fade at about that time due to the drop in temperature and 20 minutes prior to civil dawn, the garden Blackbird joins in the dawn chorus and obliterates the sonogram. He also tends to sing up to and occasionally just beyond dusk. The local Robin starts earlier in the morning and later in the evening and whilst the song obscures some things it isn't as loud and is more constrained with fewer harmonics with long pauses between phrases. Song Thrush would be quite bad except the closest seems to be about 100 yards away - slightly different to a decade ago when a pair bred in the garden. Other resident species recorded after dark include Rooks, Crows, Jackdaws and Magpies both as they enter/exit roost and occasionally when they are disturbed. The local Pheasants cluck away enthusiastically from the small hours but irregularly enough to not be a nuisance. I haven't heard Grey Partridge yet.

Finally we come to owls. Tawny Owl seems straight forward enough as there is a pair nearby but not within the street. They occasionally duet but mostly it is the male. He calls most often after midnight for a couple of hours but can call at anytime when he duels with other birds in adjacent territories. Barn Owl https://www.xeno-canto.org/544661 is a bit more complicated. Until last night I had heard it on a couple of occasions, always sounding distant. Yesterday I found a single feather in the garden and whitewash on the wall. Last night a distant call was followed up very quickly by a call from within the garden. There was further whitewash on the fence and on the bird table. I have no idea where this bird might be nesting - there are no barns immediately adjacent and few mature trees. This is something I will be following up for sure.

So how have I found it? NocMig is quite overwhelming initially - everything sounds different. I am pretty confident on my ID from sounds during the day, doing surveys almost daily for 10 years and lots of CBC which is primarily by ear and yet the nocturnal flight calls can be bewildering. There are a number of species which give calls which seem alien to me, especially Water Rail which can sound like a wader, a passerine and like a little pig. Having said that, like anything new, it gets easier with practise. I am processing the recordings faster each day although it still takes 3 hours or so. I am familiar with all the creaks and groans and now recognise the sonograms for the regular species. Most importantly I am absolutely loving it. There is a voyage of discovery each morning and the joy of solving a puzzle or adding something unexpected and new is amazing. Given the current situation with Covid-19 it is gratifying to find something where I am learning a new skill, building upon this and it has potential professional ramifications. My Zoom H1n is dead easy and all the information you need to get started is out there including survey protocols, how to use audacity, how to analyse the data and support groups on ID on WhatsApp, Facebook, Xeno-canto and Twitter. If this all sounds fun then definitely get involved. It cost a total of about £100 including rechargeable batteries and a dead kitten style wind shield for the mics.