68 THE CONDOR Vol. XXIII 
Yet when one finds that this measurement in groups of 11 males from Marin Coun- 
ty, 10 from Sonoma County, and 8 from Suisun, Solano County, averages 2.6 mm. in each 
group, while the distance from nostril to end of bill averages respectively 15.1, 15.8, and 
16.1 mm., you have something to compare with a group of males (11) from Stockton, 
which shows the former measurement to be 3.0 and the latter 15.4 mm., making it ap- 
parent that the bill of the Stockton bird is appreciably thicker than any of the above 
groups. Again, a Tuolumne River group of 13 males has 3.3 and 15.2 mm. for these 
measurements, showing a still heavier bill than the Stockton bird. 
While the variations among different groups of the same species may weaken the 
significance of this data to some extent, it is still valuable when used in conjunction 
with other characteristics. However, not having had sufficient opportunity to carry on 
these studies to a conclusion I will not dwell longer upon the subject, but will close by 
saying that I shall be glad to be of service, if needed, to any one indulging in this pas- 
time.—JosEPH MAI“iIarD, California Academy of Sciences, San Francisco, January 21, 
1921. 
Pileated Woodpecker versus Cooper Hawk.—On January 31, 1921, while we were 
on our way to Mirror Lake, Yosemite Valley, we heard the loud, ringing call of the Pile- 
ated Woodpecker. Looking up we saw two rather large birds dashing through the tree- 
tops. The dark bird with the white wing-patches we recoginzed at once as a Pileated: 
the lighter colored bird turned out to be a Cooper Hawk. A pursuit was apparently in 
progress, but as the birds dashed through the branches of the tall trees it was impossible 
to be sure which of the birds was the pursuer and which the pursued. Both birds quickly 
left our range of vision, but a little farther on we heard gentle tappings and soon located 
the woodpecker. The hawk was there, too, perched on a limb a few feet away. The wood- 
pecker was drilling and prying off chips with apparent unconcern, while the hawk 
looked on with seemingly hungry eyes. While we were watching, the hawk flew to a: 
branch a few feet above the woodpecker. Pileated tilted his head and gave the hawk a 
sidelong glance and then deliberately flew toward him and drove him from the tree. 
With the hawk gone, the woodpecker went on with his drilling as though nothing had 
happened. Perhaps the hawk saw visions of a good meal, but lacked the courage to attach 
a bird so well equipped to give battle-—CuHas. W. MICHAEL, Yosemite, California, February 
2, 1921. 
Two Unusual Winter Records for the San Francisco Bay Region.—The White- 
throated Sparrow (Zonotrichia albicollis), a rare winter visitor to this region, has once 
more appeared on the campus at the University of California, Berkeley, after an appar- 
ent absence during the winter of 1919-1920. A single individual was observed in company 
with two Golden-crowned Sparrows foraging in the shelter of shrubbery along Strawber- 
ry Creek, December 17, 1920. 
On December 19, 1920, a stormy day, with heavy wind, at my home in Oakland, I 
was attracted by an unusual bird call. I could not identify the bird at this time because 
it flew too quickly into shrubbery, but subsequent visits proved it to be a Western Mock- 
ingbird (Mimus polyglottos leucopterus). Other known dates of this bird’s visits to my 
garden, where it has spent most of its time in a large toyon berry bush, are December 
26, 1920, and January 2, 16, and 24, 1921. Every visit has been announced by harsh, un- 
musical call notes.—MArGARET W. WyTHE, Museum of Vertebrate Zoology, Berkeley, Cali- 
fornia, February 17, 1921. 
An Afternoon with the Holboell Grebe.—In the last issue of the Condor I read an 
interesting article on the nesting of the Pied-billed Grebe and its habit of carrying its 
young on its back. The writer of the article, Mr. Bancroft, says that the young were 
not carried under when the parent bird dived. Perhaps the following passage from my 
note-book, which treats of this Grebe habit, may be of interest: 
On the afternoon of June 24, 1914, I loaded my canoe in the democrat and went 
with a friend to Silvermore Lake. After launching our canoe we found nine nests of 
Holboell Grebe (Colymbus holboelli), with 2/3, 2/2, 1/6, 3/1 and 1/4 eggs, respectively. 
While paddling around we noticed a Grebe swimming along with a young one on her back. 
At times the young bird was almost invisible beneath her feathers and wings as it moved 
