Cambridge, Mass.
1903
July 3
  Clear with fresh north-east wind.
  The Solitary Vireo with two songs is still in
our neighborhood & still singing both songs freely and with
about equal frequency. Yesterday afternoon he came into
"the Jungle" and Walter Deane & I watched him there
for ten or fifteen minutes. At one time he approached within
six feet of us & perching on a dead twig only a couple of
yards above the ground uttered the V. flavifrons song
continuously for several minutes. During this time he did not 
give a single note which the keenest expert in bird music
could have distinguished from that of a Yellow-throated Vireo. 
In short the entire song was absolutely typical of flavifrons
in every respect. Equally so of solitarius was the song which
had preceded & which shortly followed it, not a single
tone, quality or inflexion being wanting. Indeed when he sees 
fit to appear in the musical role of his own species he is
one of the finest performers I have ever heard with a
superlatively wild, clear ringing voice. The most remarkable 
thing about it all is that he apparently never by any
chance interpolates a note of one song among those of the other.
He is indeed either a Solitary or a Yellow-throat as the
mood serves but never both in the same breath. Usually
he keeps silent for a minute or two before singing the 
other song but sometimes he changes from one to another
often on intervals of only a few seconds. I cannot detect
anything abnormal in his color or markings. He has a clean
"blue" head, a well marked eye ring & was yellow beneath
save on the sides. He has been singing in the Garden
as I have been writing this changing his song twice during
the period. I have never seen any other Vireo with or very
Solitary Vireo with two songs.