My granny lived in Stenhouse in Edinburgh, on the ground floor of a tenement building.  At the back of her house was a shared 'drying green,' which was a large (ish) area of grass where people hung washing to dry.  Beyond that there were small vegetable gardens, a couple of broken down air-raid shelters, then the railway.  (A man was said to have unearthed a nest of rats while digging in one of the vegetable patches.  I don't know if it was true). 

I spent quite a bit of time, in bad weather, looking out over this garden from my granny's kitchen window.  One thing I remember was that it was full of birds: dark little birds that ran quickly across the garden, lots of them, together.  These birds did not have a good reputation: people called them 'vermin,' and I took their word for it.  However, there was something striking about these birds - there was purple and green among the black of their (probably city-dirty) feathers.  They were starlings.

Over the house where I live now, on a clear day at sunset, starlings fly, together, in swooping, splitting, plunging formations.  It is incredible to watch.  This phenomenon is called a 'murmuration.'  When I went to check the word, I could not find it in the Oxford Concise dictionary.  It is not there.  Later, I did find it in my older, larger dictionary, but it is down as an 'alleged word' from about 1470.  Alleged word? Interesting.

'Murmuration' - Google it. You will be amazed.