232 Birds of Colorado 
in El Paso co., April 5th and 15th, and there is an example taken 
September 10th in the same county in the Aiken collection. On the 
western slope it occurs at Grand Junction in spring. 
Habits—The remarkable dissimilarity of the two 
sexes in this Woodpecker, caused them to be at first 
regarded as two different species. The male was known 
as S. walliamsoni, the female as S. thyroideus. Henshaw 
(74) first found the two supposed species breeding together 
at Fort Garland, and solved the difficulty which had 
always been felt in regard to them. In most respects 
Williamson’s Sapsucker resembles the Red-naped, but 
is apt to be somewhat shyer and more wary. It feeds 
on insects and their larve, but whether it bores for 
sap like the other form, appears to be rather uncertain. 
I have found no undoubted evidence on the subject. 
It has rather a shrill cry, “‘ Huit, huit.” Gale says: 
“This species affects generally old pine or spruce trees, 
and stumps that are rotten and easily worked, frequenting 
the same tree for several years, but making a fresh hole 
each year. It occasionally chooses aspens, but if it 
excavates for itself it chooses a rotten tree. Sometimes 
it uses an old hole of a Red-naped Sapsucker.” 
The male does most of the work, both of excavation 
and incubation ; when the female is on the nest, he sits 
on a branch near by and warns her of danger by a special 
tapping. The eggs, five or six in number, are laid from 
about May 30th to June 15th. They are white and 
often somewhat pyriform in shape, which is unusual 
in this family. They average -95 x ‘68. 
Genus PHLCEOTOMUS. 
Of large size—wings 8 to 10; bill stout, longer than the head, with 
well marked culminal and lateral ridges; head conspicuously crested ; 
toes four, the outer posterior (fourth) shorter than the outer anterior 
(third); plumage chiefly black with a red crest. 
Only two closely allied subspecies found in the United States. 
