Saturday, May 2
Time: 9 a.m. 
Weather: cool (40s), bright and breezy

Seven people walked out as far as where the Wilson Trail loops back to the
shoreline on the north side of Sapsucker Woods Pond. Our first notable bird
was a swamp sparrow in the reeds at the northeast corner of the lab. It was
a large heavily streaked individual, nearly the size of a female redwing,
but with the recognizable sparrow bill. Between the parking lot and the
Owens Observation Platform we saw many redwings (male and female), including
a female on the nest in the cattails at the south edge of the pond. There
were tree swallows flying over the pond and when one alighted on the high
tension wires I mentioned Iding ³B.O.W.s² by their posture. Swallows look
neckless and slightly hunched. I introduced the idea of the Peterson field
marks: characters that can be seen at a distance and tend to be unique to
that bird as compared to similar birds. E.g., the snow-white breast and
belly of the tree swallow. Out on the platform the wind was from the north
and the noise of the airport smothered the bird sounds, although we did see
two belted kingfishers flying in different directions and grackles flying
every which way.

In the wooded wetland immediately north of the lab a warbling vireo was
singing persistently from a nearly fixed location. Its lack of wing bars,
clear gray breast and lack of pronounced head stripes, along with its
³languid² uninterrupted song gave it away. This individual did not have a
pronounced light stripe over the eye. I made mentioned of the variation
among birds of the same species, saying that Sibley was good about including
multiple examples. Someone spotted a female robin with nesting materials in
her beak and also later found the nest; she was squirming around in it,
creating the characteristic bowl shape.

Once in the woods we began to hear many birds singing including:
goldfinches, more warbling vireos, a house wren, and robins. We noted the
tendency of the goldfinches to interrupt their song with their call note. We
saw a pair of cowbirds (male and female) and noted their dissimilar
appearance, but shared conical bill, unusual for a blackbird.

As we drew nearer the thickets between the trail and the Sapsucker Woods
Pond we began to hear yellow warblers singing. We also saw several
chestnut-sided warblers, but they did not seem to be singing, but instead
devoted their time to foraging. We compared them to the cedar waxwings,
which were moving much more slowly, and feeding on fox grapes from last
year. Someone saw one waxwing feed a berry to another. Folks spotted the
yellow cap of the chestnut-sideds before they saw the eponymous feature.
When the yellow warblers were seen I told everyone to look for the variation
in the darkness and extent of the chestnut striping on the breast and sides
of each male.

A least flycatcher appeared, hunting for flying insects in its usual sally
forth fashion. I contrasted it with the foraging technique of the
chestnut-sided warblers, which were gleaning the insects directly from bud
clusters at the tips of branches. Although the flycatcher is about the size
of warbler, it moves and sits very differently.

As we climbed the embankment to the pond we heard and then saw a male
redstart, singing vigorously and moving from place to place quickly, but not
apparently feeding. A catbird or two was also singing here. Across the pond
to the west a male Baltimore oriole was singing in the top of a tree. He
flew toward us and then over through the woods to the north. An apparently
fearless muskrat foraged along the shore in the alders distracting most
people from birdwatching for a few minutes.

Along the path returning toward the lab there were chickadees, cardinals,
all the warblers we had already seen and in the distance a yellowthoat sang
his witchity-witchity song a couple of times.

We wrapped up the trip with another visit to the Owens observation platform
where a great blue heron was fishing with repeated success. His breeding
finery is already starting to fade with his bill no longer orange all the
way to its base.