Earlier, Michael Price suggested that Hutton's Vireos might be migratory
in the Pacific Northwest. I have not noticed this with the local pairs
(2-3) which nest/winter in Cougar Canyon (Delta BC, just south of
Vancouver.) The habitat is mostly deciduous, with some old-growth. Both
nests I have found have been in young (30 feet maximum tall) cedars. I
follow them quite religiously, and have their daily patterns quite mapped
out, so I am pretty certain it is the same pairs during both summer and
winter. I would suggest, then, that most pairs are not migratory.

However, I have heard of people banding them in fairly large
numbers in Washington State during migration. I also saw one at Iona
in 1995; I doubt it was resident. So, I guess some do move. Perhaps it
depends on age; young birds seem to disperse from Cougar Canyon in fall.

Although I have not noticed any regional "dialect" in their songs, I have
observed them calling on several occasions. They have a very rasping,
harsh call; quite different from the Ruby-crowneds "chi-di-dit". I find it
useful in confirming identification (although it is pretty rare to hear
them call).

I am also interested in the seeming increase in Hutton's Vireo sightings.
Is this just increased observer awareness, or a real increase. I would
have thought them to be decreasing due to Brown-headed Cowbird parasitism.
Jamie Smith tells me that they are are one of the species hardest hit in
his study in Burns Bog. Neither of the nests I found in the canyon had
BHCO evidence. An example of the increase is the Reifel/Alaksen (an area
notorious for BHCO density). There were at least two nesting pairs last
year.

Are Hutton's Vireos decreasing/increasing elsewhere in Tweeterland?