The Northern Black Swift 
site, Mr. Vrooman found 
a dull white egg, which 
the Black Swift consent¬ 
ed to own by repeated 
visits. Then to quiet 
the last doubt which 
Science otherwise would 
never have ceased to 
voice, the collector se¬ 
cured the parent birds 
and added their skins to 
the shipment, “Exhibit 
B,“ which went to the 
foremost connoisseur in 
the land, Col. John E. 
Thayer, of Boston. 
While it might have 
been called an accident 
which first betrayed the 
secret of the Black Swift, 
it was the sort of acci¬ 
dent which befalls only 
the knowing, and the 
alert Vrooman was not 
slow to profit by the 
lesson of the second find. 
Putting the two situa¬ 
tions together and 
noting the coinciding 
features, the naturalist 
determined on a revised 
campaign. Discon¬ 
nected facts began to 
come into relationship, and partially forgotten details took on significance. 
Slowly but surely the investigator came to an understanding of Swift 
psychology which enables him to locate an egg or two of these shifting, 
wary creatures almost every season. Hence, to the credit of the first 
discovery, so richly deserved, has been added the record of unchallenged 
honors for twenty-two years. It would, of course, be presumptuous 
to say that no one else could find a Black Swift's egg; but the eloquent 
fact remains that no one has. 
In the season of 1914 it was the privilege of the writer to accompany 
Taken in the Yosemite Photo by the Author 
NEVADA FALLS 
A CONJECTURAL NESTING SITE OF THE BLACK SWIFT 
979 
