Birds, 



6757 



wings folded longitudinally ; there were about thirty heads, which 

 probably helped to digest the rest. 



" We have thus, I think, very good evidence that these great swifts 

 do not content themselves with the insects which a single locality 

 may furnish, but search for large congregated swarms, — are swarm- 

 destroyers. And this quite conforms with the irregularity of stay on 

 any particular spot they visit. Some very remarkable points with 

 regard to their mode of finding these swarms have latterly much 

 attracted my attention. Let me give two examples. On the 20th of 

 August, just before I shot the first bird, I had heard the column 

 coming up. A good number of Progne were skimming low over a 

 grass-covered mound in the pasture, of about an acre and a half in 

 extent, and two of the swifts with them, for they always join and 

 explore a flock of another species. Soon the number increased, and in 

 a short time the column had disappeared, and a hundred and fifty or two 

 hundred birds were dashing in every direction over the spot. They 

 continued in different parts of the meadow adjoining the hillock, till I 

 shot the next. On the 3rd instant I heard them again coming, but 

 this time from the forest above. Just as I got out, the column, com- 

 posed of numerous birds, descended and deployed over the meadow, 

 but I presume found nothing, for they speedily formed again, gyrating 

 slowly and moving along the western ridge, thus approaching the house, 

 Though it was still distant three hundred or four hundred yards, seve- 

 ral birds were shooting in an impetuous, irregular way over the house 

 round the neighbouring trees, dashing even through the yard, without 

 any apparent object rising to some height, then darting up the river 

 course for a great distance, and back again. As the column pro- 

 gressed along the ridge, which it did very slowly, a man walking 

 along the path would have arrived opposite the house before it. 

 There skimming birds became more numerous ; perhaps ten or 

 twelve were over the yard and house at once, and the whole space 

 between the house and the ridge was equally densely occupied by 

 great numbers of birds shooting about low, in the same wild, irregular 

 manner. The column stopped a little, and then moved in the same 

 direction. It now began to leave the house, and the skimming birds 

 became fewer. If one was selected, and its motions watched atten- 

 tively a little, it would be evident that, notwithstanding its irregu- 

 larity and amazing rapidity, its deviations did not prevent it from 

 steadily keeping after the column. As this passed out of our little 

 valley, and became scarcely visible over the intervening ridge, now 

 one and then another bird might be seen darting after it in a straight 



