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Is it a Bird? Is it a Plane?

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Is it a Bird? Is it a Plane?

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Walking out to my field last week, I spotted a glowing white bird perched on a fencepost. The first Wheatear of the year – a lovely male with fresh plumage lit up by the low winter sunlight. 

Migration season is now upon us, and plenty of people will be rushing out to their back gardens this spring with a microphone and a satellite dish contraption. Arise, nocmiggers!

What the Heck is a NocMigger?

Every night, huge flocks of birds pass over our sleeping houses unseen. In fact, the majority of migratory birds fly at night, when the risk of predation is low and the birds may use the moon and stars to help with navigation. At this hour, the air is calmer, with less wind whipped up by the shifting patterns of sunlight on the surface of the earth, and heat levels are lower, so flying is more efficient.

But all the twitchers are sleeping in their beds when this nighttime miracle is occurring. Well, not all of them – some of them are outside listening for the sound of a passing Snipe, or have set up specialist sound equipment to record overflying birds. Enter the ‘nocmiggers’ – a contraction of ‘nocturnal’ and ‘migration’.

Nocturnal Migration sound recording
As the sun sets and night draws in, millions of birds set off on migration across the sky. Others lie in wait below.

A Wing and a Prayer

The standard setup for nocmiggers is a parabolic microphone. The mic sits at the bottom of a big dish, which amplifies the sound from above, and only picks up airborne birds, rather than the drunken arrival of your neighbour at 4AM.

In fact, you can pick up a parabolic microphone for as little as £25 on eBay. It won’t be a good one, mind you. The better the microphone, the easier it is to identify the birds, as you’ll get a cleaner signal. BirdGuides have a very detailed introduction to setting up a sound recording system on their website.

Nocmiggers view the signals from the audio recording as a visual readout – a ‘spectrogram’ – on a computer, which they match up manually to a vast library of bird calls. These calls come from the bird nerd paradise ‘Xeno Canto‘ – a free library of global birdsong.

You’ll find that there’s a whole community of nocmiggers on Xeno, who can help with identifying troublesome recordings. Of course, AI birdsong identification is already in use in some places, though many birders prefer to do this bit ‘by hand’.

Crested Lark audio signature
This spectrogram shows the call of a Crested Lark.
"crested.lark" by dobroide is licensed under CC BY-SA 2.0.

Naked NocMiggers

Even within the nocmigging community, there is some debate about whether recording birds on a microphone really counts as ‘birdwatching’. Can you actually tick the species off your life list if you weren’t there to hear it call? 

Enter the ‘naked nocmigger’ – these are the truly hardcore who stay outdoors in the chill of night, listening out ‘live’ for birds to fly overhead.

Fortunately enough for our mental picture, there isn’t actually any need to be naked, to indulge in ‘naked nocmigging’. The naked just refers to stripping off the layers of technology until you are truly exposed to the raw sound. These naked twitchers may take a whole night to hear a single bird, without the amplification and noise reduction that’s possible with proper sound recording tech.

Frosted Glass
Frosted glass can reduce bird strikes at night, though solutions like microdots are easier to see through.

Safe Flying

Given how many species of bird fly at night, perhaps it’s easier to understand the concern that many birdwatchers have with skyscrapers. When lights are left on in these buildings, birds are likely to head for the windows and die upon impact.

In the USA, it is estimated that at least 100 million birds and perhaps as many as 2 billion lose their lives each year in collisions with windows. There’s now a movement towards bird-safe design in the States for windows in tall buildings. This includes using patterned glass, or film which is retrofitted to existing windows. Small dots across the surface can alert a bird to the oncoming hazard, allowing it to change path before a collision.

But in the UK, our councils have been slow to act on this threat to biodiversity. A 2022 investigation found that none of the UK’s biggest cities had any policies in place which would protect birds from striking large buildings. Even at home, especially need a bird feeder, bird strikes on windows are relatively common. Window films and sticky dots are a fairly inexpensive and attractive solution to this problem.

Hoopoe
Species like Hoopoe, Bee-eater and Glossy Ibis are now becoming more common sights in the UK. This Hoopoe was taken in Cornwall by Nick D'Agorne (c)

Accidental Beauties

Nocmigging has opened our eyes – and our ears – to the vast populations of birds moving through urban and suburban areas at night. It’s exciting to think of all the species which could plop down in your garden, smallholding or farm, if there’s suitable habitat.

Typically, birds will visit the same patch of land each year, rather than straying to another part of the country. But inclement weather on migration may force them down into other habitat or sweep them past their destination. And we’re now beginning to understand the potential of these accidental vagrants, with stunning species like hoopoe, bee-eater and glossy ibis regularly turning up, and now starting to breed in the UK.

So keep an eye and an ear out, and make your land as biodiverse as possible, for one day those overflying rarities might just pay you a visit.

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