THE YELLOW-HEADED BLACKBIRD. 449 



Incubation, as nearly as I have been able to ascertain, lasts about fourteen 

 days, and the young- are able to leave the nest in about sixteen days after 

 hatching. 



By the 1st of Aug-ust the Yellow-headed Blackbirds have gathered into 

 large flocks and then roam about in search of good feeding grounds. They fly 

 in compact masses and at this time associate to some extent with Brewer's and 

 the Red-winged Blackbirds. By the middle of October they gradually disappear 

 along the northern borders of their range and move southward, wintering- in our 

 southwestern States and in northern Mexico. 



The eggs of the Yellow-headed Blackbird vary in shape from ovate to ellip- 

 tical and elongate ovate; the shell is finely granulated, strong, and rather glossy. 

 The ground color varies from grayish white to pale greenish white, and this is 

 profusely and pretty evenly blotched and speckled over the entire surface with 

 different shades of browns, cinnamon rufous, ecru drab, and pearl gray. The 

 markings are usually heaviest about the larger end of the egg, and sometimes a 

 specimen is met with which shows a few fine, hair-like tracings, like those found 

 on the eggs of the Orioles. 



The average measurement of one hundred and thirty -four eggs in the United 

 States National Museum collection is 25.83 by 17.92 millimetres, or about 1.02 

 by 0.71 inches. The largest eg-g in the series measures 28.96 by 19.81 millime- 

 tres, or 1.14 by 0.78 inches; the smallest, 23.11 by 17.53 millimetres, or 0.91 by 

 0.69 inch. 



The type specimen. No. 20233 (PI. 6, Fig. 10), from a set of three, was 

 taken by the writer at Malheiu- Lake, near Camp Harney, Oregon, on June 3, 

 1876, and represents one of the coarser marked and larger eggs; Nos. 25028 

 and 25030 (PL 6, Figs. 11 and 12), both fi-om sets of four, taken by Dr. Edgar 

 A. Mearns, United States Army, near Fort Snelling, Minnesota, May 27, 1891, 

 represent the finer and more common styles of markings, and show the variations 

 in size as well, the former showing- also a few hair lines which are not often 

 found on the eggs of this species. 



174. Agelaius phoeniceus (Linn^us). 



RED-WINGED BLACKBIRD. 



Oriolus plioeniceiis Linnaeus, Systema ISTaturae, ed. 12, I, 1766, 161. 

 Agelahis ]}lueniccus Swainson, Fauna Boreali Americana, II, 1831, 280, 

 (B 401, C 212, R 261, C 316, U 498.) 



Geographical range: Temperate North America; north in the eastern parts of 

 the Dominion of Canada to about latitude 49°; in the interior to Great Slave Lake and 

 Fort Simpson, Northwest Territory to about latitude 62° N. ; and on the Pacific Coast, as 

 far as known, to southern British Columbia. South in winter to Costa Rica, Central 

 America. Accidental in England, Italy, etc. 



The breeding range of the Red-winged Blackbird, also known as the 

 "Swamp" and "Marsh" Blackbird, is nearly coextensive with its geog-raphical 

 distribution both in the United States and the Dominion of Canada. It is one of 



16896— No. 3 29 



