Above: Carrion Crow, Tattenhoe, April 2017 (All photos, images and recordings © Harry Appleyard)
One of my long-term missions in my local birding has been to record as many species as possible from within the Tattenhoe area in the south of Milton Keynes. While there are many places I could visit across the rest of the city to generate a much longer species list, I prefer to base mine on a lower-carbon approach, through what I see and or hear close to home. Currently, my list of species for Tattenhoe and the surrounding areas since 2008 sits at 128.
Having already listed the resident species, as well as frequent annual migrants, new additions come at a much slower pace now, but an increasingly talked-about area of birding that I’m hoping will help me, is ‘nocmig’, the recording of nocturnal bird migration. After some research with the aid of other birders on Twitter, I invested in the Tascam DR-05 last year. While I can’t say it has added anything new to the list yet, it has been well worth getting into, having recorded several species I’ve never previously observed from my garden before, some of which have been rare or only occasional on my walks in this corner of MK in the past.
The recorder is placed into a bucket coated in bubble-wrap, to suppress background noise. The AA batteries for the recorder usually just about make it through a 6-7 hour recording, however they will run out of power much sooner on cold or windy nights. Its minimum operating temperature according to the product manual is 6 degrees Celsius, so ideally not one to leave out in the open in winter. WAV format is usually one of the better formats to choose for recording, as MP3 audio may not be quite as clear for distant sounds and more vulnerable to compression.
After I’ve finished the recording, I scan through the audio using Audacity. Amplifying the audio by around 20-24 decibels has been key in picking out the bird vocals, as unless they are perched close to the bucket or calling as they fly directly over the garden, not only are they harder to hear, but also harder to see in the spectrogram, where visual signatures of their vocalizations can be found among the other sounds of the night.
Once the audio is amplified, the next stage is scrolling through the spectrogram, which can be expanded and magnified to make finding the often-fleeting calls of nocturnal migrants much easier. Most vocals from passing birds on the audio are thin dots and streaks, though the louder they are and the more they are magnified, the more unique and recognisable they become. Sudden knocks or movements of objects nearby and typical urban sounds like car horns or distant alarms, may look like vocals on first inspection.
The dawn chorus is often a mess of streaks and lines all over the spectrogram from typical garden visitors like the Wren, Robin and Crow, even more so earlier in the summer when warblers and other birds are in the mix. When the display starts to get crowded, it’s worth listening closely for early morning flyovers, or birds you might not usually see in your garden, like the Bullfinch.
Findings from 2019 to Present
Since I started the recordings, the Moorhen has been one of the more frequent night-time flyovers, interestingly regarded as a common nocturnal migrant across the UK but it’s hard to be sure whether I have caught true migrants travelling long distances or resident birds disturbed from their territories nearby, perhaps flushed from their roosts by foxes or cats in the early hours of the morning.
Having seen them only once in the garden before, Tawny Owls have also been a pleasant surprise, occasionally perched and calling nearby. From the night of 23rd October and into the morning of 24th October 2019, the recording picked up at least a dozen flight calls from Redwings and a Blackbird. 2020 has been much more productive in variety of species so far, largely thanks to already having the recorder ready for use through the peak migration period in spring.
Recording of Tawny Owl, 10th September 2019
Of the 59 bird species I’ve recorded from the garden so far this year, 5 of them have been picked up exclusively on the overnight recordings. 26th March produced a Coot at around 2.54am, an infrequent visitor to Tattenhoe’s waterways rather than established resident like its close relative the Moorhen. 5th April produced my first garden record of Oystercatcher, an occasional flyover here in recent years, calling as it passed over at 00.50 am, with another a few weeks later at around 1.13 am on 15th June.
By far the most exciting bird I’ve recorded since starting this and the least expected one for my suburban garden was a male Nightjar, churring for a few minutes somewhere nearby at 3.55am on 31st May, just as the dawn chorus was starting to kick off. Surrounded by houses with a few deciduous thickets nearby, this isn’t the sort of place where I would have actively been looking out for them initially, however in research and speaking to other birders online, I found out that they have been known to travel several kilometres away from their heathland- and woodland-based breeding grounds while hunting. He could have also been a passing migrant, albeit a late arrival, like the one I found hawking around an oak tree further along the Tattenhoe valley on 2nd October last year.
Below: Spectogram and recording of Nightjar churring among Robin song, 31st May 2020
Two other firsts for my garden since the Nightjar have been the Little Grebe, calling at around 1.16 am on 11th June and 3 am on 21st July and another rare flyover for the Tattenhoe area, the Little Ringed Plover, making two calls at 1.34am on 15th July. Small passerines have also made brief callouts in the dead of night, with single bursts of song from a Blackcap at 23.49 on 14th April and a Lesser Whitethroat just after midnight on 21st May.
Below: LIttle Grebe, recorded 11th June 2020
Below: Blackcap, photographed Howe Park Wood, April 2017; Recording of male Blackcap, Tattenhoe, 14th May 2020
A typical night usually starts with traffic noise, with the last two hours ending with a gradual build-up of garden birds. The fleeting flight calls of passing migrants have been few and far between so far but nonetheless, it’s a small project that has proven well worthwhile, helping to record several species I’ve rarely come across within this locality in the daytime, plus more locally common species that I haven’t previously heard at night.
This is a field of birding I would love to hear about more people in Milton Keynes getting into. With such a diverse range of habitats across the city, there are near countless possibilities for what might get recorded along the way. It has proven to be a great way of picking up rarities and local scarcities across the UK, such as the Ortolan Bunting, Bittern and Quail.
Do not feel pressured into having to know all the vocalizations of British birds before you get started. There are plenty of guides online that can help you along the way, plus websites such as Xeno-canta which are packed with thousands of bird songs and calls, many of which are labelled as nocturnal recordings. Searching ‘#nocmig’ on Twitter has usually been my way of keeping an eye on what other people have found on their recordings across the country, which has been useful for finding out about unprecedented night-time movements of species like the Common Scoters, plus positively identifying flight calls during the height of migration through spring. With Autumn migration starting to kick off, now is a great time to get started, the sooner the better!
I am still a beginner with this and have much to learn about the technicalities of audio enhancement and recording, but I am pleased with the results so far. A website I would highly recommend checking out, should you wish to get stuck in is: https://nocmig.com/.