144 BULLETIN 17 9, UNITED STATES NATIONAL MUSEUM 



the second— 16% and 15% days, respectively. She continues : "The 

 incubation periods of the phoebe vary more than do those of any 

 other species that I have studied closely. Not only do the tirst nest- 

 ings average a little longer incubation period — about one day — ^but 

 the time the young stay in the nest is longer by one day than in the 

 case of the second nesting. The female alone incubates." Frank 

 L. Burns (1921) gives the period of nestling life as 15 to 16 days. 

 During this time both parents bring food to the young birds. 



The nestling phoebe has no difficulty in leaving the nest when it is 

 normally placed, but, as we have seen above, the nest may be built 

 below the ground (in a well or shaft), under a bridge across a stream, 

 or in an inclosure such as a room in a house, from which it is diffi- 

 cult for a fledgling to reach the open air. In such cases the little 

 birds find themselves in a precarious situation; they may be forced 

 to fly upward or to some distance to avoid a stretch of running water, 

 or to direct their flight through a tiny opening. Nevertheless, they 

 appear to extricate themselves generally without mishap, although 

 they spend little more time in the nest than young wood pewees do 

 that need only to walk out on the level branch by the nest or to flutter 

 to a branch below. 



Fledgling phoebes are pretty little birds, prettier when they leave 

 the nest than they will ever be in their lives again. They are not 

 dingy like their parents ; their backs are pale olive, and their wings 

 are crossed by two distinct buffy bars. They are alert and active 

 even on the day they leave the nest and flit to a branch and perch 

 without awkwardness, twitching their short tails ably with the down- 

 ward sweep characteristic of the adults. They utter frequently a little 

 peeping note — tereep or trree — feebler, longer and less sharply pro- 

 nounced than the cA2^ of the old birds. 



Dr. Dayton Stoner (1939a) made a detailed study of the develop- 

 ment of young eastern phoebes and found the incubation period to be 

 16 days; the young^ he says, reach "near-adult size within a period 

 of 17 days." 



Plumages. — [Author's Note: The natal down of the young phoebe 

 is "mouse gray" or "light drab," which only scantily covers the 

 feather tracts. Wlien the bird is four or five days of age the flight 

 feathers begin to grow, followed soon by the contour plumage, with 

 the natal down adhering to the tips of the juvenal feathers. The 

 Juvenal plumage resembles that of the adult, but the upper parts are 

 browner, "clove brown" on the crown and nape and "olive-brown" 

 on the back, wings, and tail; the feathers of the lower back, rump, 

 and upper tail coverts are broadly tipped with "cinnamon-buff" ; the 

 greater and median wing coverts and the rectrices are tipped with 

 "cinnamon-rufous," and the secondaries and tertials are edged with 



