[mou] Warbling Vireo on the nest

[Alt, Mark]

There were many highlights of the Pine County Birding Festival, based
out of Northwoods Audubon in Sandstone, MN, yet a standout was finding a
Warbling Vireo singing in the town of Finlayson right along the Willard
Munger bike trail. Mike Link had led us there to get a look at Black
Terns working over a small lake, large pond covered with lily pads. We
watched as the terns fed repeatedly in the center of the pond. The song
of a Warbling Vireo laid down an acoustic backdrop for the whole event.
There were 12 or so of us birders, and the strip of trees that promised
the vireo was only 10 feet thick before it dropped off to the lake
below. There were Ash trees right along the trail - 30 feet tall, then
Willows took over down to the lake.=20
We clustered where the song emanated from. It was a blustery day and the
thin warble seemed to be thrown a bit on the wind.  A few of us crouched
down right along the edge of the woods, and Julie Brophy soon called out
"There is an Oriole nest in the trees in the backdrop." She called out
that "Oooh, there's the bird singing from the nest!" We soon realized it
was a Warbling Vireo nest with a male singing from within it, with only
his beak and the top of his head visible. The nest was about ten feet
high relative to where we were standing, in a willow. The nest was in a
forked branch, midway out on the branch, maybe 4 feet from the main
trunk. On this windy day, the willow moved quite a bit and the ash tree
I n the foreground obscured it thoroughly.  Julie did well to pick it
out. Kneeling down improved our sightlines.  Laura Erickson got her
scope on it and soon everyone had world-class views. Laura digiscoped
it, you may see the image at this URL:

http://www.birderblog.com/bird/Species/Vireos/WarblingVireo/Photos/IMG_9
687.jpg


The Warbling vireo nest interested me and I check out some references to
fill in some of the details of this bird I have seen so many times but
not in this way. The nest at first resembles a short stocky oriole nest,
but is more of a basket rather than a purse. The bird sits atop the
nest, not inside. BNA clarified how the nest was made; that the female
weaves the rim in a fork of a branch and then works downward an outward,
leaving it a suspended pouch woven into a tree fork.  On average, it
takes 7 days to construct this nest.  Spider webbing, grass blades and
other materials it can find are used to weave it. There are records of
females singing, but rarely, so it was the male we heard this day,
singing his song while he incubated eggs. According to BNA, the male
takes less than 40% of this shift work, so we were lucky to have its
location proclaimed for us.
 	Warbling Vireo males are known for singing on or near the nest,
so if you are hearing the rhythmic "when I see you I will squeeze you
and I'll squeeze you till you squirt" drifting down consistently from
your neighborhood willows or cottonwoods, look for the globular
basket-like hanging nest, tightly woven into a middle fork of an outer
branch, probably on the eastern exposure of the tree, to protect from
afternoon heat, and then scan carefully for the rather drab, effusive
songster, lurking nearby or perhaps even sitting atop the nest. Enjoy
it, it is sublime. Breeding Birds are what it is all about. Good
Birding!

Mark Alt
Brooklyn Center, MN