226 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 93 



tophorus calling in the mountains on various occasions but did not 

 succeed in locating them. The higher mountains beyond Catemaco 

 that have not been explored may easily harbor forms whose presence 

 now is not suspected, and the great lowland forests along the sea to 

 the west and northwest of Puerto Mexico offer many possibilities. 



MIGRATION 



Located near the Gulf of Mexico at the northern end of the Isthmus 

 of Tehuantepec, the Tuxtla region is on the route traversed by hosts 

 of avian migrants from the United States and Canada. Many re- 

 main through the period of northern winter, and others pass in 

 flight to or from more southern localities. Of the 291 forms in the 

 present list, 86 are certainly northern migrants, while some indi- 

 viduals of various other forms, as some of the herons and other water 

 birds, undoubtedly come here as visitors from farther north, though 

 part may be resident in the locality. The number of migrants among 

 aquatic species will be increased considerably by more extended ob- 

 servations in the marshy lagoons and along the larger rivers. Our 

 records do not cover the period of fall movement but begin in Janu- 

 ary and continue through the spring. 



Among the attractive sights to the naturalist in the Tropics of the 

 New World, the great flights of migrant hawks that pass through 

 Mexico and Central America twice each year rank among the fore- 

 most. The majority of these fine birds that made the spring flight 

 north at Tres Zapotes in 1939 were Sennett's white-tailed hawks, 

 but occasionally other species traveled with them. Northward move- 

 ment began at the end of March and flights passed almost daily, 

 usually in the forenoon, with the birds soaring in circles and at the 

 same time drifting steadily. toward the north. At times 50 or more 

 were visible at once crossing the sky to disappear over the northern 

 horizon, followed steadily by more, until I sometimes wondered how 

 many passed in the course of a day. The flights in 1939 continued 

 until I left the region on April 1G. One morning I shot an everglade 

 kite from one of these bands, and on April 6 and 10 turkey buzzards 

 passed in flight northward, evidently migrant individuals of one of 

 the two northern subspecies. 



The smaller migrants, familiar summer residents of eastern and 

 central North America, often came in waves as they do farther 

 north. On March 21, 1939, following a tremendous rain that flooded 

 all the low -lying country and drenched the jungle, I found the bushes 

 and weeds of old fields crowded with orchard orioles, yellow warblers, 

 and parula warblers, with others in lesser numbers. These birds 

 continued in abundance until March 25, when there was a noticeable 

 decrease among them. March 30 I recorded that another wave of 



