BIRDS OF SOUTHERN VERACRUZ — WETMORE 227 



migrants had come in during the night, and from then on the pro- 

 cession seemed constant. During the end of March and early April 

 I saw more orchard orioles near Tres Zapotes than I had observed 

 in all my previous years of observation of this species in its northern 

 home. On some days they fairly swarmed, so that it was necessary 

 to scrutinize carefully every bird collected to avoid shooting them. 

 Lincoln's sparrows, common as winter residents, also increased de- 

 cidedly at the end of March for a brief space. The period from 

 March 25 to April 15 seemed to mark the height of the migratory 

 movement as a whole, though some species were passing until early 

 May. 



Other interesting migrants were the Merrill's pauraque {Nyetidro- 

 mus albicollis merrillii) and Couch's kingbird (Tyrannus melan- 

 cholicus couchii) , which in our northern summer come barely within 

 the southern boundary of the United States. Some of their number 

 come to live briefly, in winter, with the resident races of the same 

 species in the Tuxtla region. 



That there is definite migration among some species wholly trop- 

 ical in distribution is a fact that is becoming constantly better known 

 as our observations extend. In the Tres Zapotes area, the yellow- 

 green vireo (Vireo flavoviridis flavoviridis) falls in this category. 

 Seemingly this bird withdraws after its nesting season, so far as 

 most of its individuals are concerned at least, into South America, 

 to return the following season to its breeding grounds. In 1939 I 

 noted none to the time that I left on April 16. The following year 

 Carriker found the first one on April 6, followed by another April 8, 

 after which they were common. Possibly the white-bellied emerald 

 hummingbird (Agyrtria Candida Candida) may be a migrant also, 

 since, although it was common in March both years, in 1940 Car- 

 riker did not record it until February 28, after which it was widely 

 distributed. The sulphur-bellied flycatcher (Myiodynastes luteiven- 

 tris luteiventris) appeared on April 1. 



The striped flycatcher (Legatus leucophaius variegatus) also seemed 

 to be migrant here, as it suddenly became common in April, though 

 not recorded earlier. The Mexican crested flycatcher (Myiarchus 

 tyrannulus nelsoni) was common after the middle of March but was 

 not seen in winter. The peppershrike {Gyclarhis guianensis flaviven- 

 tris) was recorded only after the first of March. Since it is found 

 usually by its song, it may have been present earlier, though silent. 

 The beginning of March marked the opening of its breeding period. 



Further study in the field is needed to verify some of the observa- 

 tions just listed, which are based on scanty data. It appears, however, 

 that there is definite shifting among some truly Tropical species for 

 purposes of breeding. 



