436 U.S. NATIONAL MUSEUM BULLETIN 237 p^kt i 



It seems that the very long span of breeding dates can hardly be 

 explained in terms of replacement layings after a loss of an earlier 

 clutch or brood. More likely, either some birds breed twice in some 

 years or different parts of the population breed at different times. 



Plumages. — There is little sexual dimorphism although, after the 

 Juvenal stage, and presumably among birds of equal age and state of 

 plumage wear, males are usually more brilliantly colored. This 

 applies especially to the yellow portions of wing and tail. 



Breeding adults are grayish brown above, heavily streaked with 

 dusky; the paler rump is often tinged with yellow. Wings and tail 

 are mainly dusky. The basal portions of the flight feathers are 

 yeUow, and are conspicuous in flight but almost entirely concealed 

 when the birds are at rest. There are two narrow whitish wing bars. 

 Underparts are whitish, heavily streaked with dusky except from the 

 abdomen posteriorly when it is often plain. The bill is brownish or 

 dusky at the tip, becoming paler (flesh colored or bluish) toward the 

 base, especially the lower mandible. The iris is brown. Legs and 

 feet vary greatly in color, but usually are medium light to a darker 

 shade of brown. This breeding condition is a result of wear and fading 

 of the plumage acquired months beforehand by a partial post-juvenal 

 molt in the case of young birds and a complete postnuptial molt in 

 the case of adults. 



At Rutherglen, Ontario, in 1948, siskins were plentiful and nested. 

 Mrs. Louise de Kiriline Lawrence (MS.) saw the first flying young on 

 May 10. On May 22 females with incubation patches were noted 

 going into molt and, in general, acquiring fat — first on the abdomen, 

 then on the axilla, and last on the fulcrum. The birds then left the 

 area, the last seen on June 3. 



After the postnuptial molt — details of it have been described by 

 T. and E. McCabe (1928) — the new fresh plumage has these character- 

 istics: orange-buff wing bars; strong dusky markings and yeUowish 

 edges on back feathers; buffy or yellowish tint on abdomen (which 

 may be either heavily or hghtly streaked or plain); and buffy chest 

 and flanks. 



Although the natal down has been observed quite often, apparently 

 no description of it has been published. The photographs in the 

 article by T. L. Rodgers (1937) indicate that a well developed nestling 

 down exists. 



The development of the juvenal plumage has not been described; 

 it is developed to the point that initial flight occurs at 15 days of age. 

 This plumage is more buffy and warmer in general tone than the 

 worn breeding plumage of the adults it associates with, so the two 

 age groups then can be distinguished afield. After wear and fading, 

 it is very similar in general aspect to that of worn adult plumage. 



