Dear Readers, there are few sights in nature so compelling as a starling murmuration, and this is a great time of year to see one. Once upon a time you could even see this event in central London – I used to sit with my Mum on a bench in St James’s Park overlooking the lake, and the starlings would fly in from all directions as the light faded, massing and pulsing, the shape of the flock constantly morphing and changing until finally they settled for the night. In ‘Nature’s Calendar’, Kiera Chapman has a wonderful description:
‘A liquid swirl of birds in a twilight sky, like billowing smoke become animate, rippling and pulsing in an aerial ballet of contoured Henry Moore figures, sometimes shimmering and transcendent, sometimes ominously threatening. The unearthly sound of their wings overhead, like the sound of the distant sea‘.
There is something about a mass of individual animals acting as one that is spine-tingling and can bring me close to tears. Have a look at this film, and see what you think.
There are different views about why starlings have this evening ritual. Some suggest that it confuses predators, especially peregrine falcons. Chapman explains how, when a murmuration is relaxed, the flock is ‘diluted’ – spread out in space. When the birds spot a peregrine actively hunting, the birds bunch together in a response known as ‘blackening’. You can sometimes see a pulse spread through the flock in what’s called a ‘wave-event’, as each bird tries to get closer to the bird in front, causing a black line to pass through the murmuration. If the peregrine suddenly dives from above the birds scatter in a ‘flash expansion’, rather like a bursting firework. The murmuration may also split in two to avoid a peregrine, or even develop a hole where the falcon is flying, known as a ‘vacuole’. If you watch the murmuration film above, you can see several of these changes, and others beside. And in the photo below, a falcon to the top right has caused the murmuration to bunch up and split into two parts.
Anyone who has watched a murmuration will be astonished by how quickly the whole ‘organism’ can change direction. Craig Reynolds, a computer scientist working in the 1980s, built a model of this behaviour based on only three factors:
- Each bird avoids colliding with other birds
- Each individual bird would try to match the speed and alignment of the birds around it
- Each bird would try to move towards the centre of the murmuration (birds on the edge are more likely to be predated).
These simple rules provided a pretty good model for group behaviour in animals, but normally you would expect to see them diluted across a flock as it thinned out, and this doesn’t happen with murmurations – one little bird seeing a falcon can influence the behaviour of all of its flock mates in a fraction of a second. Scientists now believe that starlings are so attuned to a sudden change in direction of another bird that they are in effect primed – the murmuration exists in a state of what’s known as criticality, on the edge of changing at all times. This means that information from any single bird is transmitted across the whole murmuration with, as Chapman says, ‘incredible speed, and without loss’.
This extraordinary ability to react doesn’t always serve starlings, unfortunately. A few years ago several hundred dead starlings were found in a lane in Anglesey, which created all kinds of theories about what had happened. Scientists came to the conclusion that the birds had tried to avoid a bird of prey but the birds at the tail-end of the murmuration hadn’t been able to pull up in time, and had struck the road and been killed. In 2010 a similar incident occurred in Somerset, though here the thought was that the birds had mistaken the gravel drive of a house for a reed bed and had misjudged the height. But be that as it may, the biggest danger to starling murmurations is the fall in number of the starlings themselves and the destruction of their habitat. You will look in vain for such a sight in central London these days, after starlings were evicted from places like Leicester Square because they were too messy and noisy. I hope that the descendants of those birds have moved to the seaside and joined one of the last big murmurations that I know about, around Brighton Pier. There’s a really nice short film here showing what happens, and it’s really tempting to just jump on a train and go and see it! Maybe there’s something a bit closer to home though. Do share if you know of any murmurations in London. I feel deeply nostalgic for the sights of my youth.