Specimens from Costa Rica and Guatemala, being merely winter visitors to that region, are quite identical with North American examples.
Habits. This but little known species was first described by Mr. Cassin, in 1851, from a specimen shot by him in some woods near Philadelphia nine years previously, which was then unique, and remained so for some time after. This fact, and its resemblance to V. gilva, led to the impression that it might be only a variety of that species. Since the publication of the description other specimens have been procured from different localities,—Moose Factory, Maine, Ohio, Wisconsin, Costa Rica, and Guatemala. But little is as yet known in regard to its habits or its distribution. It is quite abundant in the spring in Southern Wisconsin, where it appears only as a migrant passing north, none remaining to breed. As it makes its appearance late in May, and usually passes rapidly on, it seems natural to infer that it cannot be far from its breeding-place at the period of its appearance. The specimen obtained by Mr. Cassin was shot in September, on its southward journey. It was in the upper branches of a high tree, capturing insects; and his attention was drawn to it by its slow and deliberate movements.
Mr. Thure Kumlien, of Dane County, Wis., informs me that he has been familiar with this Vireo since 1849, and has collected it every year since
that period, finding it both in the spring and fall. It appears occasionally as early as the 10th of May, the time varying with the season from the 10th to the 27th. In 1857, when the season was very backward and May very cold, they did not arrive until June 2. They were unusually numerous, and remained only a day or two. So far as he has been able to ascertain, none stop to breed. They are very quiet, have no song at the time they are passing, and seem only intent on collecting their food and in proceeding on their way. They are very tame and unsuspecting, and one can readily get to within a few feet of them. In the fall they are returning south from the 7th to the 19th of September.
The nest and eggs remain to be obtained.
Vireosylvia gilvus, Cassin.
WARBLING GREENLET.
Muscicapa gilva, Vieill. Ois. I, 1807, 65, pl. xxxiv. Vireo gilvus, Bon. Obs. Wils. 1825, No. 123.—Aud. Orn. Biog. II, pl. cxviii.—Ib. Birds Am. IV, pl. ccxli.—Baird, Birds N. Am. 1858, 335.—Samuels, Birds N. Eng. 273. Vireosylvia gilva, Cassin, Pr. A. N. Sc. 1851, 153.—Sclater, P. Z. S. 1856, 298 (Cordova); (?) 1858, 302 (Oaxaca; June) (perhaps V. swainsoni).—Baird, Rev. Am. B. 342. Muscicapa melodia, Wils. Am. Orn. V, 1812, 85, pl. xlii, fig. 2.
Vireo gilvus.
988