Monday, May 13, 2019

Like a Veery in Reverse! Rare Morning encounter with a pair of Neotropical Swainson's Thrush birds

As you can see - the range for this bird just dips into the area of Minnesota where my mini-forest site is. Which is northern minnesota, closer to lake superior.

The Swainson’s Thrush was an uncommon species during the Minnesota Breeding Bird Atlas (MNBBA).
The song - all I knew is it was an upward glissando that had repeated notes as it went up

That precisely fits the Swainson's Thrush - unlike the Veery. This is very amazing.

So some of these recordings are not so clear

this is better

One thing to keep in mind is that birds have "regional" differences in their songs.

Its song is flute-like, ascending spiral like Veery in reverse.
So the past couple years I've had a Veery couple. That's why I was very surprised to hear this type of glissando (like a Veery has a glissando) but this glissando definitely was NOT a Veery and this glissando went up.

https://www.allaboutbirds.org/guide/Swainsons_Thrush/overview

that's a strong recording.

THAT'S WHAT I HEARD - hear in the background - that double repeating rising sound in the background!!

 Thanks to my birding old friend from my undergraduate ornithology class - and also housemate in my hippy commune - for cluing me into this bird as the probable cause.

https://www.audubon.org/field-guide/bird/swainsons-thrush

So here we get a list of songs.

So far I have not found another recording with the same "double repeating rising sound" that is in the background of that Swainson's Thrush recording. So I am assuming that is the same bird - as what marks their call is an upward glissando by repeating notes - and it has different "styles" to it.

 I'm still not sure that "double repeating rising sound" in the background that starts about halfway through - if that is Swainson's Thrush. I'm waiting for confirmation. I still don't know why it would NOT be but it's very different from the other type of the songs on that same recording or the other recordings. It's still an "upwards" repeating and glissando type song. So....

OK I emailed the scientist in charge of researching the effects of global warming  on the Swainson's Thrush song. I just wanted to make sure that I know what I'm listening to.

We'll see if he can respond - you would hope so, even if he is busy -he is paid to do this as his job.

During these contests, rivals very occasionally invert their customary melody so that it spirals downward in pitch
So the Swainson's Thrush flies all the way from Central America - the Osa Peninsula in Costa Rica! I was there in 1992.

Stopover behavior and migratory pathways of neotropical migrant birds in Central and South America have received little study. We examined stopover ecology of Swainson's Thrush (Catharus ustulatus) on the Osa Peninsula, Costa Rica, during spring migration, 2002–2005. Capture rates per net hour were high (;amx = 21.8 individuals/100 net hrs) suggesting large numbers pass through lowland coastal areas in spring.
That's really wild to think that little bird had just been in Costa Rica!!!

On winter grounds in Central and northern South America, the species inhabits closed-canopy forest and can often be found attending army-ant swarms.

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