ioo BIRDS OF LA PLATA 



covered nests, the two species are identical* But 

 when the breeding-season comes their habits begin 

 to diverge ; then the Common Cow-bird lays in nests 

 of other species, abandoning its eggs to their care ; 

 while the Bay-wings usually seise on the nests of 

 other birds and rear their own young* Yet, as they 

 do occasionally build a neat elaborate nest for them- 

 selves, the habit of taking possession of the nests of 

 other birds is most likely a recently acquired one, 

 and probably its tendency is to eradicate the original 

 building instinct. 



October 8. This morning, while reading under a 

 tree, my attention was aroused by a shrill note, as 

 of a bird in distress, issuing from the neighbourhood 

 of the Firewood-Gatherer's nest ; after hearing it 

 repeated at intervals for over twenty minutes, I went 

 to ascertain the cause* Two Bay-wings flew up from 

 the ground under the nest, and on searching in the 

 rank clover growing under the tree, I discovered the 

 female Lenatero, with plumage wet and draggled, 

 trembling and appearing half dead with the rough 

 treatment she had experienced. I put her in the sun, 

 and after half an hour, hearing her mate calling, 

 she managed to flutter feebly away to join him. The 

 persecutors had dragged her out of the nest, and 

 would, no doubt, have killed her had I not come so 

 opportunely to the rescue. 



Since writing the above I have continued to watch 

 the nest. Both the Bay-wings and their victims left 

 it for some days. Six days after I had picked up the 

 ill-treated female, the builders of the nest came back 



