View From The Shed by Shaun Finnie - WHO NEEDS CARROTS?

WHO NEEDS CARROTS?

You and I are mostly diurnal by nature. That means that we do most of day-to-day living in the hours of sunlight. If we were mainly active at dawn and dusk and resting when our surroundings are fully light or dark we could be described as having a crepuscular lifestyle. For many of us, diurnal and crepuscular will be new terms, but I suspect that we've all heard of the third alternative; nocturnal.

If you read my last week's RSPB Dearne Valley blog which mentioned our surprise visitor, the Night Heron (who is still to be seen at our Adwick Washlands reserve at the time of writing), then you'll remember that this particular bird is nocturnal, which means that it lives most of its active life in the night time.

We can't see too well in the dark but some birds, such as the Night Heron, are much more comfortable seeing in lower light levels. This is where it gets scientific. Strap yourself in and, if you're more than a few pages ahead of me in the Big Book of Eye Composition, please forgive my simplistic understanding of the subject.

The retina at the back of our eyes is composed of photoreceptors that help translate the incoming light into understandable images. Going way, way back to my O level biology, I remember that these photoreceptors can be either rods or cones. The rods are the ones that distinguish light from dark and the cones differentiate between the many colours in the spectrum our eyes can handle. The receptors in a human eye are around 95% cones and 5% rods as most of our vision is required in bright, colourful daylight, but that isn't necessarily the same for other animals. Most birds can see a much larger range of colours than we can but the way it works for them is basically the same as for us – rods and cones, contrast and colour.

For a creature to have proficient night vision it needs to have many more rods than we do, usually at the cost of fewer cones. This would mean that they can see quite well in low light conditions but colours wouldn't stand out much. We might not be able to see the actions of these nocturnal birds but there is a way that we birdwatchers can 'watch' them at night – and it doesn't involve night vision goggles.

Many predator birds need excellent daytime eyesight to hunt, so it makes sense for some of their prey species to avoid them and do their long distance flying at night-time. Quite a few of our favourite migrating songbirds do exactly this as they pass from one continent to another. There's safety in numbers too, so they usually keep in constant contact with each other while traversing the night skies making frequent calls that basically all mean, “Here I am”. This is good news for us as it means that even if we can't see them on their night flights, we might just get a chance to hear them. Which brings me nicely to a word which was new to me and might just be new to you as well. As regular readers will know, I'm fascinated by language and how it evolves. Old words fall out of use and new ones are formed to describe things that simply weren't 'things' in previous generations.

Nocmig is an entire subset of birding in itself, although the numbers who practice it are far fewer. Want to join them? All you really need is a good ear, a quiet place from which to listen and a lot of patience. The word 'Nocmig' is derived from NOCturnal MIGration and is the opposite of 'Vismig'. Nocmig practitioners study migration through the night when you cannot see your subject; Vismig refers to VISible MIGration and is the passage of migratory birds during the daytime. Most of us have seen prime examples of that this year with birds like the Spoonbills that are currently to be spotted around our Dearne Valley reserves.

Sit out in your garden with a warming drink of some kind, face up to the sky and just listen. Maybe you hear some birds calling to each other high up in the darkness? Are they Pink Footed Geese? Perhaps Godwits of some kind? Could you recognise either? This is the most basic way of birdlistening but it relies a lot on the hearing and identification skills of the person involved. Most Nocmiggers just go to bed and let technology do its thing. They record through the night and then run the recorded sounds through identification software. That's basically it. With a bit of practice and experience you can learn to identify the sound wave shapes that various birds' contact calls translate to. There's no doubt though that it's much easier with the software. It pretty much comes down to, “Hey Alexa, what bird makes a sound matching this sound wave picture?”

If you fancy giving this very different area of birding a go for yourself there's an excellent introduction at this RSPB page and a lot more info on the Nocmig site or the BTO's pages. It's a fascinating branch of citizen science and you'll be astounded at what flies overhead while you're unconscious overnight. There are so many more birds that go through your local patch of sky than come down to your local patch of land. Just imagine how many species you could add to your yearlist?

And those carrots? Are they really going to help you see in the dark? Well no, they aren't - but that's not to say that they aren't good for your eyes. Carrots are a great source of vitamin A which is required as part of the body's constant renewal of the cells of the eye. So eating carrots won't make you see any better but it will keep your eyes refreshed and healthy. There's usually some truth in those “old wives' tales and superstitions. Many of them just happen to be about birds too. Hmmm, I can feel another blog coming on...