SYCAMORE YE'LLOW-THROATED WARBLER 361 



almost exclusively to the trees which skirt the streams, and move 

 northward by day with considerable rapidity." 



The main migration route seems to be almost directly northeast- 

 ward, from western Mexico and Central America to western North 

 Carolina and Ohio, and more directly northward through the broad 

 Mississippi Valley to Michigan and Wisconsin. This is markedly 

 different from the migration route of the eastern race, which migrates 

 nearly northward along the Atlantic coast. 



Nesting. — Whether the nest of the sycamore warbler is in a cypress 

 or in a sycamore, it is always placed at a considerable height from the 

 ground, for this is a treetop bird. Nests have been recorded at 

 heights ranging from 10 to 120 feet above the ground, but probably 

 most of them are between 30 and 60 feet up. Mr. Butler (1928) de- 

 scribes two Indiana nests of similar construction. One was — 



built about 35 or 40 feet above the ground in a flat crotch, on an approxi- 

 mately horizontal limb of a large sycamore tree. * * * The nest measures 

 as follows : Outside diameter 2.50 inches ; inside diameter 1.65 ; outside height 

 2 inches ; inside depth 1.75 inches. The heavier frame was composed of shreds 

 of grapevine barli, bits of the covering and coarser fibre of weeds, mingled with 

 which were many small pieces of cotton cord or ravelings. The nest was lined 

 and its entire bottom was composed of the soft down obtained from dry syca- 

 more balls. In fact the nest really had no foundation for the bottom, the lining 

 material reaching through to the limb. [The other] was about 75 feet above 

 the ground in a crotch of small branches toward the end of a sycamore limb 

 which was not strong enough to bear one's weight. It was so hidden by the 

 foliage that it could not be seen until some of the leaves fell this autumn. 



A set of four eggs is in the Eichard C. Harlow collection, taken by 

 W. C. Avery, Greensboro, Ala., April 24, 1893. The nest was in a 

 liquidambar tree, 26 feet up and 9 feet out from the body of the tree, 

 on a horizontal branch and nearly concealed in the TiUandsia in which 

 it was built. George Finlay Simmons (1925) says that in Texas the 

 nests are sometimes built in an elm or a pecan tree, from 12 to 35 feet 

 from the ground. 



Eggs. — The sycamore warbler lays from 3 to 5 eggs ; in most cases 4 

 eggs seem to complete the set. Mr. Simmons (1925) describes them 

 as "dull greenish gi-ay-white; marked with distinct and clouded 

 blotches, specks, and under-shell markings of lavender, purplish-gray, 

 umber, and brownish-red ; and sometimes even blackish spots ; usually 

 wreathed about the larger end." The measurements of 10 eggs aver- 

 age 16.9 by 12.7 millimeters; the eggs showing the four extremes 

 measure 17.6 by 12.1, 16.2 by 12.8, and 16.6 by 13.0 millimeters. 



Plumages. — The sequence of plumages and molts is probably the 

 same as for the yellow-throated warbler. 



Food. — Very little seems to have been published on the food of this 

 warbler, but it probably does not differ materially from that of the 



