Aretas A. Saunders contributes the following notes on the song of this warbler: "The parula warbler has two distinct types of song. One is a simple buzzy trill rising in pitch, and frequently terminated by a short, sharp note of lower pitch. Of 12 records of this song, 7 have the terminal note and 5 do not. The other form has the same buzz-like quality, but begins with three or four short notes on the same pitch, followed by a longer, higher note that is frequently, but not always, slurred upward. Both songs are similar in length and in pitch intervals. They vary from 1-1/5 to 1-3/5 seconds in length. The rise in pitch varies from one to four and a half tones, and averages about two tones. The actual pitch is exceedingly variable in individuals and varies from A´´´ to D´´´´´. Songs vary considerably in loudness, many of them becoming suddenly louder toward the end. "The species sings throughout migration, and on the breeding grounds till late July. At that season I have seen males still singing while feeding young just out of the nest." _Enemies._--Dr. Friedmann (1929) writes; "This bird is practically free from that greatest enemy of most of the warblers, the Cowbird. Occasionally, however, parasitic eggs are found in the dainty pensile nests of the Parula Warbler. Stone found a nest on May 26, 1892, at Cape May Point, New Jersey, containing three eggs of the Warbler and one of the Cowbird. * * * Five other records have come to my notice, from Long Island, New York, Pennsylvania and Connecticut, and the bird is listed as a victim of the Cowbird by several writers, as Bendire, Davie, and Chapman." Mrs. Nice (1931) records two more cases in Oklahoma. Harold S. Peters (1936) records two lice, _Myrsidea incerta_ (Kellogg) and _Ricinius_ sp., as external parasites on this species. _Field marks._--The parula, is one of our smallest warblers. The adult male is well marked, with its blue upper parts, the yellow back being inconspicuous, two conspicuous white wing bands, black lores, yellow breast and chestnut or blackish throat band. The female is duller in all colors, more greenish above and has little or no throat band. Young birds are even less conspicuously marked, as noted in the description of plumages.