418 BULLETIN 17 6, UNITED STATES NATIONAL MUSEUM 



on upper tail-coverts and middle tail-feathers; in having the cin- 

 namon-rufous on basal portion of the tail far more extensive, there 

 being more on the middle rectrices in A. heloisa, while on the others 

 it occupies very much less than the basal half, and is entirely hidden 

 by the coverts; the sides and flanks are less deeply, and apparently 

 less extensively, cinnamon-rufous, and the under tail-coverts are white 

 or but very faintly buffy, instead of being deep cinnamon-buff." 



In his "Birds of North and Middle America" (1911), Eidgway 

 treats Morcom's hummingbird as a subspecies of Atthis heloisa^ under 

 the name Atthis heloisa morcomi^ which he characterizes as "similar 

 to A. h. heloisa^ but smaller (except bill) ; adult female paler below, 

 with bronzy spots on chin and throat much smaller, sides less exten- 

 sively cinnamon-rufous, and under tail-coverts pure white." 



According to our 1931 Check-list, morcomi is not accorded even 

 subspecific rank and is regarded as identical with A. h. heloisa^ to 

 which race our Arizona specimens are now understood to belong. 

 This is the race that is found in central and southern Mexico, from 

 the States of Tamaulipas, Guanajuato, and San Luis Potosi to 

 Guerrero and Tepic. 



Nothing seems to be known about the habits of this subspecies and, 

 so far as I know, the nest of the species has never been found. But 

 Alexander F. Skutch has sent me the following notes on a closely 

 related form, Elliot's hummingbird {Atthis heloisa ellioti), the 

 Guatemalan race. 



"Like so many of the Central American hummingbirds, the male 

 Elliot's hummingbirds gather in definite assemblies to sing. Al- 

 though I have found them in western Guatemala from 6,000 to 11,000 

 feet above sea level, they appear to be nowhere common. Yet where 

 one finds a male singing persistently, day after day, from the same 

 perch, there will generally be one or more others within hearing. 

 About the middle of October 1933, 1 found an assembly of four males 

 on a steep, bushy slope at an altitude of about 9,000 feet. Each bird 

 had chosen as his singing perch the bare, exposed twig of a bush or 

 the low branch of a tree. Their headquarters were separated from 

 each other by 25 or 30 yards. They were stretched out in a line; 

 and the birds in the middle could each hear two of their neighbors, 

 but those in the end positions could hear only the one nearest to 

 them — unless their ears were sharper than mine, which is certainly 

 not improbable. These hummingbirds did not perch so close to- 

 gether by chance, for I found none other of the kind within a mile of 

 this assembly. 



"The assembly was established in a spot not far from the highway 

 that crossed the mountain ; and whenever I passed that way I would 

 pause to listen, enchanted, to a song that amazed me, coming from so 



