736 MICHIGAN BIRD LIFE. 
APPENDIX 2. 
HYPOTHETICAL LIST. 
This list includes species which have been attributed to Michigan but whose status, for 
one reason or another, is doubtful. 
Western Grebe. Achmophorus occidentalis (Lawr.). (1) 
A western species, breeding from British Columbia to northern California, 
and from Saskatchewan to North Dakota, and straggling eastward ac- 
cidentally as far as Minnesota and Wisconsin. In spite of numerous 
references to this species we have failed to find a single good record for 
Michigan. Holbcells Grebe seems to have been mistaken for this species 
quite generally, but with little excuse. The fact that the neck of the 
Western Grebe is nearly or quite as long as the body, and the culmen 
always more than 24 inches long separates it sharply from any other grebe. 
Eared Grebe. Colymbus nigricollis californicus (Heermann). (4) 
This is another western species which sometimes strays eastward as 
far as the Mississippi, and casually even farther. It has been reported 
several times from Michigan, but we have been unable to verify a single 
instance. There is a genuine specimen in the University of Michigan 
Museum at Ann Arbor, said to have been taken in the vicinity, but the 
data are open to so much question that the specimen must be ignored. 
Mr. Norman A. Wood writes that another specimen was taken at Saline, 
Washtenaw county, January 10, 1879, by William Minett. We have not 
been able to verify the determination of this specimen, or even to make 
sure that it is still in existence. Butler records two specimens for Indiana 
and there are several others from eastern points. In winter plumage, 
our common Horned Grebe might be mistaken easily for this species, 
but the shape of the bill is diagnostic. See key to species of grebes, page 
36 of this volume. 
Black-throated Loon. Gavia arctica (Linn.). (9) 
Synonyms: Black-throated Diver; Arctic Loon. 
Smaller than the common Loon and larger than the Red-throated Loon, 
this bird is most likely to be confounded with the latter species. Its 
tarsus, however, measures less than the middle toe without the claw, 
while in the Red-throat the tarsus measures more than the middle toe 
and claw. The winter plumage of the three species is so nearly identical 
that only a careful comparison of proportions and measurements will 
separate them satisfactorily. 
The present species is a rare winter visitor to the northernmost waters 
of the United States and probably occurs once in a while on Lakes Superior, 
Michigan, and Huron. Jcneeland includes it in his list of Keweenaw Point 
birds (1857), and it figures in several of the old lists. Possibly some 
of these ‘“‘records” were based on specimens actually taken, but apparently 
