Henry Mousley (1924) recorded his observations on two nests of magnolia warblers, and found that during a period of 15 hours, at one nest containing very young birds, the male fed the young 34 times and the female 58 times; the average rate of feeding was once in 9.8 minutes; the female did all the brooding for a total of 6 hours and 19 minutes; the faeces were eaten 9 times and carried away 17 times, about equally by each sex.
Margaret Morse Nice (1926) made a very elaborate study of the happenings at another nest; her account, containing many interesting observations, to which the reader is referred, is too detailed to be quoted here. Her table shows that she watched the nest for a total of 261⁄2 hours, spread over a period of 9 days; during this time, the young were fed by the male 118 times and by the female 91 times; the average rate of feeding was once in 7.8 minutes; the female brooded 33 times for a total of 352 minutes; the faeces were eaten 8 times and carried away 38 times.
Aretas A. Saunders (1938) writes: “After the young have left the nest, they are much in evidence in the forests. As soon as this happens, whatever territory there was is abandoned. The young wander away, keeping together, and the parents care for them, feeding them frequently for the first few days. Both sexes feed the young, but after a day or two only the male is likely to be in attendance. Young in this stage are easily located by the incessant hunger calls. These calls consist of three or four high-pitched notes, tsee tsee tu—tsee tsee tsee tu—tsee tsee, etc. I cannot distinguish the call made by young of this species from those made under similar circumstances by the young of the black-throated green and blackburnian warblers.”
I have also received from Mrs. Doris Huestis Speirs and from Mrs. Louise de Kiriline Lawrence very full reports on their observations at two nests of magnolia warblers in Ontario. Many of their observations were similar to those mentioned; however, the following should be noted here: Mrs. Lawrence found the incubation period to be about 11 days, incubation and brooding being by the female only. The young were fed by both parents by regurgitation for the first 3 days, and after that on solid food, mostly caterpillars; in 49 minutes, the male fed them 7 times and the female 5 times. During 51⁄2 hours, the male ate or carried away the fecal sacks 15 times. The young left the nest on the ninth day after hatching, and were fed by their parents up to the twenty-fifth day after leaving the nest; after that they were seen feeding themselves. Mrs. Speirs kept an accurate record of the brooding periods, which were from 8 to 45 minutes in length, but seldom less than 20 minutes, the female leaving the nest for periods of from 3 to 15 minutes. At times she closed her eyes and seemed to doze; occasionally she rose and turned the eggs with her feet or bill. The presence of birds of other species approaching or flying over did not seem to disturb her but the movements of a red squirrel in the vicinity kept her alert. The story of this nest ended in tragedy; some predator destroyed all but one of the young, the female finally disappeared and eventually there was nothing in the nest but an unhatched egg. A sharp-shinned hawk had been seen flying over.
Plumages.—Dr. Dwight (1900) calls the natal down “sepia-brown,” and describes the juvenal plumage as “above, dark sepia-brown, soon fading, usually paler on the crown and obscurely streaked with clove-brown. Wings and tail dull black, chiefly edged with ashy or plumbeous gray, the secondaries, tertiaries and wing coverts with drab, two wing bands pale buff; the rectrices white on inner web of basal half. Below, pale sulphur-yellow, dusky or grayish on the throat, and streaked or mottled except on the abdomen and crissum with deep olive-brown. Lores and orbital region ashy brown.”
The amount of yellow on the under parts is quite variable, the youngest nestlings showing very little or none at all. The sexes are practically alike in the juvenal plumage, but become recognizable during the first fall.
The postjuvenal molt begins early in July and involves all the contour plumage and the wing coverts, but not the rest of the wings or the tail.
This produces the first winter plumages, in which the young of each sex closely resemble their respective adult counterparts at that season but the colors are all duller, the crown and back are browner, there is a dusky band on the upper breast, and the black streaking is paler or obscure.
Dr. Dwight (1900) says: “First nuptial plumage acquired by a partial prenuptial moult which involves most of the body plumage, the wing coverts and sometimes a few tertiaries, but not the rest of the wings nor the tail. Young and old become practically indistinguishable except by the wings and tail, especially the primary coverts, all of which are usually browner and more worn than in adults.” According to Dickey and van Rossem (1938) this takes place in El Salvador early in April and is completed very rapidly.