This morning, while checking in on the Cerulean Warbler that is nearest 
to my home on the southern end of Snake Mountain, for the first time in 
the 4 years of observation of the species I recorded a female.  It was 
in companionship with a male, high in the canopy, right in the center of 
the territory posted by the male by its singing since May 13th.

Being silent, muted in color, and apparently mostly in the high canopy 
(where nests, if any, likely would be located), the silent females are 
difficult to locate in the best of times .... at least where populations 
are scarce.

Based on the behavioral patterns of males at my location in previous 
years, it is about now that the birds begin to stop singing, and may 
even be preparing for out-migration from Vermont, heading back south.   
Last year the last day I observed multiple birds was June 17th, and the 
last bird observed was June 26th.   I did not see any birds on that 
territory last year any day after June 26th through July 17th when I 
quit daily surveying.

{By the way, if you view the distribution map in eBird for Cerulean 
Warbler, you will see pointers at more locations than the birds have 
been observed ..... leading to an impression that the species is more 
widespread than it actually is.  For example, the markers on the map for 
three observers seeing the same bird at the same place can show up as 
three different locations as much as 12 or more miles apart, depending 
on how they are submitted to eBird.  This is an artifact of the eBird 
reporting process, and is especially magnified for rare species.}