American Cowbirds. 137 



had a predilection for yellow wagtails' nests,"'- and as 

 nothing else would suit it, its motive in this instance 

 was, by removing the young wagtails, to incite their 

 bereaved parents quietly to build a new nest, and 

 again lay eggs beside which the crafty cuckoo might 

 deposit her own. It may be when my binoculars 

 were on the bush was just the time when the cuckoo 

 happened to be searching to see if this had been done. 



" It is true there are stoats on the marsh, but the 

 dead nestlings showed no marks of teeth. Their re- 

 lative position, and that of the nest and bush, can 

 best be shown by a sketch, and, accordingly, the 

 accompanying drawing has been made from my recol- 

 lections of this rural tragedy in bird life by our well- 

 known draughtsman, Mr. Keulemans." 



Our " accompanying drawing " is here presented 

 by kind favour of Mr. Gurney. 



This above noted conduct of the reed - warbler 

 would seem to be exactly on all-fours with the pro- 

 cedure of some of the species on which Molothriis 

 bonariensis (the cow - bird of North America, the 

 Argentine and elsewhere) is parasitical. Some species, 

 however, though they do not throw the parasitical 

 eggs out, which would seem the simplest plan, have 

 discovered how to get rid of them, and so save them- 

 selves the labour of making a fresh nest. Their 

 method is to add a new deep lining, under which the 

 strange eggs are buried out of sight and give no more 

 trouble. 



*' The Sisopygis icterophrys — a common tyrant-bird 

 in Buenos Ayres — frequently has recourse to this ex- 



* Mr. Bird found a cuckoo's egg in a yellow wagtail's nest 

 near Suttton, May 23, 1890. 



