One day at the end of March (in 1895) I saw perched on a twig of an oak tree and sitting quite close up against the trunk, a cock blackbird, which continually uttered a small, thin sharp note, almost like the squeaking of a slate pencil. He sat still in the same position for a considerable time, only opening his mouth at intervals of about a minute, or half a minute, to make this doleful noise. The same year, on June 15th, in exactly the same place, a cock blackbird went through exactly the same performance.
Every winter blackbirds have been amongst the most regular pensioners at the food-stand.
Several times during May in 1898, and again in 1899 and 1900 and since, I noticed a meeting of three, always, I think, three, cock blackbirds at one particular spot, always the same, near a holly tree on the lawn, which happens to be just opposite my window, where I could watch them easily and unobserved. They seemed to go through a regular set performance, like a game or a dance. They did not fight, though they sometimes sparred a little, but ran round and round and in and out, following and passing one another. It reminded me of a friendly gathering of husbands for amusement, while their wives were busy with household cares at home!
I was much interested one day (March, 1902) in the proceedings of two pair of blackbirds. One very elegant cock, slender and graceful, with intensely black coat and very bright orange bill, was seeking to impress the hen of his choice by a series of little runs on every side of her, with his tail spread out and sweeping the grass, his body in the shape of a bow, his beak almost touching the ground; meanwhile, the object of all this attention seemed to consider it a mere matter of course and to be calmly indifferent. Presently another cock, not nearly so spruce, came on the scene accompanied by another mate. The gallant dandy evidently had no stomach for fighting, and promptly disappeared behind a holly bush when the newcomer threatened to assault him. His partner, however, was made of sterner stuff, and without more ado attacked and drove away both the intruders.
I have never heard that there is any real difference in size, but hen blackbirds appear bigger than cocks, just as young gulls in immature plumage seem larger than old ones. I suppose the different colour has something to do with it, and perhaps the cock's feathers are more closely set than the hen's.
My wife told me that she had seen one evening in September (1907) 16 blackbirds on the tennis ground together. This seems perhaps rather a large order, as they say, but in the following September I counted nine myself, to the best of my belief, all of them cocks.