Drama at the Nortel wetland
May 18th, 2012
Yesterday in the Nortel woods, I was walking along where some stones traverse
a wet spot on the path, and heard a Sedge
singing. Sedge Wren is a small, shy and secretive bird, rare in
Ottawa. It would be a lifer for me, so I spent some time trying to spot it,
At some point, I saw one bird chase another out of the area. The chaser was a
. I couldn't tell who the chasee was, but after this
occurrence, I didn't hear the wren sing again.
Today I went back armed with my IPod, and attempted to call the wren out (if
it was still around) by playing its song. It never responded. I did get a
response though--a big one! Common Yellowthroats in the area became agitated.
They're normally skulkers (though not as secretive as Sedge Wrens) in thick
vegetation, but as soon as I started playing that song, I had multiple
yellowthroats popping up into the trees in plain view, looking around,
scolding, and then singing at the top of their voices. I got some of the same
reaction from nearby Swamp Sparrows.
One thing some people don't realize is that, while birdsong sounds cheerful to
us, it's actually somewhat aggressive. It's an expression of self-assertion
and fitness: "this is my territory and I've got what it takes to defend it."
(Think of how much energy it takes to sing all day, as some birds do. Or how
much guts it takes to do something that draws attention to yourself when
you're a small bird surrounded by potential predators.) So the beautiful
golden-throated bird popping into a tree and singing a bright, happy-sounding
"witchety witchety witchety!" was the avian equivalent of a man flexing his
biceps and saying, "oh yeah? Well check
out." (I even noticed an increase in general skirmishes, none of
them involving wrens: birds chasing each other around, and such. It had the
feel of a bar brawl. "Who, me? I didn't say it!") In fact studies have shown
that birds' testosterone levels skyrocket when they hear the song of another
of their species in their territory.
But this was a case of cross-species aggression, and, together with
yesterday's event, suggested that Yellowthroats consider Sedge Wrens to be
direct competitors. It made me wonder: could it be one of the reasons Sedge
Wren is so secretive, uncommon and local (breeding in certain places one year
and then gone the next) is because it can't stand up to other birds who share
its habitat (sedge marshes and wet meadows)? It's 4 and a half inches long,
which is smaller than most. Just an off-the-cuff theory.
The Wikipedia page
me an idea of why a Sedge Wren might not be such a popular neighbor. It says,
"he may puncture the eggs of other birds nesting nearby"!