3 May 2016 – another Swainson’s Thrush and a stunned Summer Tanager

Update: I got a call about a “cardinal” that had struck the southeast alcove window at the NRC around 1:00 pm today.  The bird was in fact a gorgeous ASY male SUMMER TANAGER (and me without my camera).  I was a bit concerned that it was on the ground (a well-meaning woman was offering it some water) and that it let me grab it pretty easily. The bird was pretty feisty, however, and when I took it to the opposite side of the building to see if it could perch on its own among the row of oaks there, it took off and strongly flew up into an adjacent tree.  It’s still dusting off the cobwebs as they say, but when I last saw it the bird was perched strongly about 20′ up in a sturdy red oak.

I’ll count this one among my stunned/trapped victims, and I’ve amended the map below accordingly.


In the last few days, the number of Swainson’s Thrushes killed by window collision at the Noble Research Center has doubled from 2 to 4. This one was an after second-year bird with fat = 1.

It’s really odd how predictably unpredictable window collisions can be.  In this case, one of the most abundant migrants through our area has only rarely fallen victim to the building I monitor – despite it being a fairly common window-kill in spring at other Stillwater buildings. I’m in my 6th year of near daily monitoring for casualties at the NRC, and during that time I’ve documented Swainson’s Thrush . . .

Is it just happenstance that two Swainson’s Thrushes are killed within a few days of each other in 2016 when the previous two records were 5 years apart?  Do the now 3 birds from 2015–2016 indicate that something has changed compared to previous years of monitoring? Do the two birds at the end of April/beginning of May in 2016 indicate that the primary movement  of Swainson’s Thrush is a week earlier than typical? My sample is, of course, much to small to help answer such questions, but it is questions such as these that keep me going day after day and year after year . . .

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3 May 2013 – Summer Tanager

The 126th casualty of the study is also the 45th species: Summer Tanager.

I found this second year male at the southwest alcove this morning.  Yesterday was unseasonably cold and windy, with occasional driving rain and even some snow flurries in Tulsa.  This young male Summer Tanager was a bit worse for wear, probably at least in part from that nasty weather.  He had a fat score of zero.

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In reading a bit about Summer Tanagers this morning, I learned that these birds are not just pouncing on poor, defenseless caterpillars as I had assumed comprised the bulk of their diet.  Summer Tanagers actually specialize on eating wasps!  Studies from both breeding grounds in the U.S. and wintering birds in the Neotropics have found bees and wasps as the most important component of their diets.  They chase them in midair, return to a branch to crush the abdomens of their prey to remove the stingers, and swallow them down.  Summer Tanagers will hunt wasps near their (the wasps’) nests, and pick off the adults one by one.  Then, when there is no more defense for the nest, the tanagers move in to destroy the colony by taking every defenseless larva.

More than ever, I’m excited by the moxy it must take to be the one thing that bees and wasps really fear.  That makes it even sadder to think that one of these noble, aggressive, and high-octane predators had its life cut short by something as stupid as a pane of glass.

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Also cool about this guy was the pattern of red coming in on his otherwise mustard-yellow plumage.  Next May, he would’ve been a spectacular rosey-red, all over.

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