Vol. XXVI 



1909^ *] Roberts, Colony of Yellow-headed Blackbirds. 373 



across the slough and there in the quill-reeds found many Yel- 

 low-headed Blackbirds, and to his surprise discovered that the 

 females were also present in full force and busily engaged in building 

 nests. Some two dozen nests were found about a little pond 

 separated a little way from the main slough. They were in all 

 stages of construction, two or three being completed and nearly dry. 

 A suitable territory for making the observations contained in this 

 paper was selected and outlined so that as little confusion as possible 

 would result in keeping tab on the nests. An area of quill-reeds, 

 then almost free from nests, was chosen. 



When, therefore, the work began on the afternoon of May 13, 

 marsh vegetation was only just starting and very little new growth 

 had sprung up among the old, dry, last year's reed stalks — only 

 a green shoot here and there. Out in the slough the wild rice had 

 not yet appeared above the surface of the water, the last year's 

 dead stubble alone being visible. The first nests of the Yellow- 

 heads are thus, of necessity, hung among the old reed stalks, only 

 the later ones including new growth, but even in the latter the rigid 

 last year's stems always form the chief support. Throughout 

 Minnesota these quill-reed swamps or 'cane-brakes,' as they are 

 often locally called, form the almost exclusive nesting sites of the 

 Yellow-headed Blackbird. So true is this that the distribution 

 of this bird, in the nesting season, is largely determined by the 

 presence of this plant. In times of high water in May and June 

 the Yellow-heads may be driven to nest elsewhere, selecting then 

 various unusual sites. Under such conditions nests may be found 

 built among bulrushes (Scirpus), and occasionally the birds are 

 forced to build in the willows bordering the sloughs, after the 

 manner of the Grackles and Red-wings. It is sometimes stated 1 

 in accounts of the nesting of this bird that it places its nest among 

 wild rice (Zizania aqudtica), but this is rendered impossible by the 

 fact that the old rice stalks are weak and fall into the water in the 

 autumn, leaving only a low broken stubble; while the new growth 

 is usually only eight or ten inches high when the nesting season of 

 the Yellow-head is over. 3 It is true, however, that in rare instances 



ij. W. Preston, Oologist, Vol. I, July, 1884, p. 36. Bendire, Life Hist. N. 

 Amer. Birds, 1895, p. 448 (quoting B. T. Gault). 



2 Attention was called to this matter and a full explanation given by Ludwig 

 Kumlien of Milton College, Wis., in ' The Osprey,' Vol. I, May, 1897, p. 117. 



