186 BIRDS OF LA PLATA 



another over the fields* It is only at the end of April, 

 three months after the old birds have disappeared, 

 that the young also take their departure. This is 

 one of the strangest facts I have encountered in the 

 migration of birds. The autumnal cold and wet 

 weather seems to be the immediate cause of the 

 young birds' departure ; but in the adults, migration 

 appears to be an instinct quite independent of atmos- 

 pheric change. 



BLACK-AND-YELLOW CRESTED 

 TYRANT 



Empidonomus aurantio-atro-cristatus 



Above cinereous ; cap shortly crested, black, with a large vertical 

 spot of bright yellow ; wings and tail brownish black, wing-coverts 

 and secondaries slightly edged with whitish; beneath as above but 

 rather paler, and with a very slight yellow tinge on the crissum ; 

 bill and feet black ; length 6.5 inches. 



ALCIDE D'ORBIGNY met with this fine species in 

 Corrientes, and Dr, Burmeister in Entrerios, and 

 again near Mendoza, In the neighbourhood of 

 Concepcion Mr, Barrows speaks of it as a " not very 

 abundant summer resident, but one not easily over- 

 looked, owing to its habit of perching on the topmost 

 twig of any tree on which it alights, making forays 

 from time to time, when tempted by its winged 

 prey/' 



In the vicinity of Buenos Ayres, which may be 



