80 FALCONID^l. 



its habits, seldom showing itself, and by means o strong legs and a 

 long, slender, wedge-like body is able to glide swiftly as a snake 

 through and under the grass. In summer one hears its long melan- 

 choly trilling call-note from a cardoon bush, but if approached it drops 

 to the ground and vanishes. Under the densest part of the cardoon 

 bush it scoops out a little circular hollow in the soil, and constructs 

 over it a dome of woven grass and thorns, leaving only a very small 

 aperture : it lines the floor with dry horse-dung, and lays five buff- 

 coloured eggs. So admirably is the nest concealed that I have searched 

 every day for it through a whole breeding-season without being 

 rewarded with a single find. Yet they are easily found by the Chimango. 

 In the course of a single day I have examined five or six broods of young 

 Chimangos, and by pressing a finger on their distended crops, made them 

 disgorge their food, and found in every instance that they had been fed 

 on nothing but the young of the Teru-reru. I was simply amazed at 

 this wholesale destruction of the young of a species so secret in its 

 nesting-habits ; for no eye, even of a Hawk, can pierce through the 

 leafage of a cardoon bush, ending near the surface in an accumulated 

 mass of the dead and decaying portions of the plant. The explanation 

 of the Chimango's success is to be found in the loquacious habit of the 

 fledglings it preys on, a habit common in the young of Dendrocolaptine 

 species. The intervals between the visits of the parent birds with food 

 they spend in conversing together in their high-pitched tones. If a 

 person approaches the solid fabric of the Ovenbird (Furnarius rufus), 

 when there are young in it, he will hear shrill laughter-like notes and 

 little choruses, like those uttered by the old birds, only feebler ; but in 

 the case of that species no harm can result from the loquacity of the 

 young, since the castle they inhabit is impregnable. Hovering over 

 the cardoons, the Chimango listens for the stridulous laughter of the 

 fledglings, and when he hears it the thorny covering is quickly pierced 

 and the dome broken into. 



Facts like this bring before us with startling vividness the struggle 

 for existence, showing what great issues in the life of a species may 

 depend on matters so trivial, seemingly, that to the uninformed mind 

 they appear like the merest dust in the balance, which is not regarded. 

 And how tremendous and pitiless is that searching law of the survival 

 of the fittest in its operations when we see a species like this Synallaxis, 

 in the fashioning and perfecting of which nature seems to have exhausted 

 all her art, so exquisitely is it adapted in its structure, coloration, and 

 habits to the one great object of concealment, yet apparently doomed 

 to destruction through this one petty oversight the irrepressible gar- 

 rulity of the fledglings in their nest ! It is, however, no oversight at 



