jMr. Swynnerton on Mixed Bird-parties. 347 



colaptidae (from species no larger than a Sparrow to others 

 the size of a Crow) running up the tree-trunks ; Tanagers, 

 Ant-Thrushes, Humming-birds, Fh'catchers, and Barbets 

 flitting about the leaves and lower branches. The bustling 

 crowd loses no time, and although moving in concert, each 

 bird is occupied, on its own account^ in searching baik or 

 leaf or twig. ... In a few minutes the host is gone and the 

 fores^t path remains deserted and silent as before. . . . Some- 

 times stray birds, encountered in the line of march, are seen 

 to be drawn into the throng, and purely frugivorous birds 

 are now and then found mixed up with the rest, as though 

 led away by some will-o'-the-wisp. . . . The simplest explan- 

 ation appears to be this : that the birds associate in flocks 

 from the instinct of self-preservation, and in order to be a 

 less easy prey to hawks, snakes, and other enemies than 

 they would be if feeding alone " *. 



Marshall, in his " Notes on ilashonaland Birds " (Ibis, 

 1900, p. 222), writes :— 



" A fact which must impress every observer is the way in 

 which one may often walk for several miles through likely- 

 looking country and scarcely see a bird ; then suddenly one 

 comes upon a troop of them, composed of Drongos, Tits, 

 small Shrikes, Flycatchers, Warblers, and Buntings, keeping 

 more or less together in a limited area. Personally I have 

 no doubt that this may be attributed to the large number 

 of birds of prey which occur here ; so that the smaller birds 

 find it advisable to associate as a means of protection, the 

 Drongos acting as a sort of body-guard.^'' 



I myself in my early notes *' On the Birds of Gazaland " 

 (Ibis, 1907, p. 34) wrote with regard to the same 

 phenomenon : — 



" . . . . Though the habit is undoubtedly a great pro- 

 tection to the weaker species, and has evidently reached 

 its present high development as a result of this, yet the 

 fact that the small ^irds peculiar to the forest — the canopy 

 and dense undergrowth of which ought to aff'ord ample pro- 

 tection from the Hawks (and Hawks are in fact scarce in 



* 'The Naturalist ou the Amazons/ vol ii. pp. ;i34 0, 1868 edition. 



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