these phenomena, and, coming one day upon such a heap of chaff or draff—though without any stack—in the centre of a small plantation of fir and pine trees, I determined to watch here, a number of small birds having flown up as I approached. I was able to conceal myself very well amidst some bushes that grew quite near, and very shortly the birds—chaffinches, bramblings, hedge and tree-sparrows, etc., but not greenfinches—were down again. I stayed a considerable while, but, except once or twice when I moved a little so as to alarm them, they remained feeding all or most of the time. Sometimes, indeed, some or other of them would fly into the surrounding trees or bushes, but this they did at their leisure, without alarm or hurry, and only as desiring a change. The simultaneousness was wanting—there were none of those nervous flights at short intervals that I had observed when watching at the open corn-stacks. Here, amongst the pines, and protected on every side, the birds felt, apparently, quite secure, though whether it was altogether a rational security may be questioned. This observation strengthened me in my conclusion as to these flights being caused by a feeling of nervous apprehension or alarm, but I am bound to add (another case of the mouse) that I subsequently watched by stacks in the open, where, also, a considerable sense of security seemed to prevail. Temperature may perhaps have something to do with the explanation, but I have as yet taken no steps to test this theory.
But whatever may be the motive (which, of course, may vary) of such sudden flights—and here I am thinking of all the examples which I have brought
