Bicknell’s Thrush Defies the Odds


Two grizzled veterans of both Mt. Mansfield and the Dominican Republic (photo courtesy of Chuck Gangas)

After 23 years of studying Bicknell’s Thrush (BITH), the improbable has become routine.  We’re still shaking our heads over the latest unlikely twist: two days ago on Mt. Mansfield, we mist netted a male BITH with a faded, dull band that had clearly logged a few miles.  Nothing unusual about this, as we capture many birds on our ridgeline site, both male and female, that return year after year (e.g., the 9 year-old I reported from last week).  I figured this was yet another old-timer.  Pulling out my laptop, I checked our records and was surprised to see an original banding date of February 13, 2010.  Obviously there had been an error of data transcription or entry.  Looking more closely, I was astonished to note that the banding site was “Guaconejo”, a scientific reserve in the Dominican Republic’s Cordillera Septentrional!  Against vanishingly small odds, we had recaptured a BITH banded by VCE’s very own Pat Johnson at its remote wet forest wintering site.  Moreover, the bird had been fitted with a light-level geolocator, which was now long gone.

It took a few minutes for this to sink in, for me to realize that this highly implausible record didn’t constitute a clerical error in our database.  Astonishment and incredulity turned to exhilaration.  We had twice previously banded BITH here in VT (one adult male on Mansfield in 1995, a nestling on Stratton in 2002) and recaptured them in the DR, but we somehow never dreamed that the reverse would happen.  It is truly difficult to fathom – the quintessential message in a bottle recovery!

Well, the plot thickens a bit, and we have to offer an admission, with a touch of humorous chagrin.  We had caught this bird not once, but twice on Mansfield in June of 2011, on the 16th and again on the 21st.  It eluded our nets completely in 2012 and 2013.  Because so many BITH return between years, we hadn’t checked this particular band number upon recapturing the bird in 2011, and it simply slipped through VCE’s not-so-airtight data radar.  However, we’ll suffer that embarrassment for the unexpected thrill of discovering the recovery three years later.  And, everyone needs a good dose of humble pie from time to time, not to mention a laugh…

As far as I know, this may be the first documentation of a south-north recovery by the person/group who originally banded the bird.  Our two previous north-south encounters were nearly unprecedented, and both merited short notes in ornithological journals.  I don’t know of an easy way to calculate the mathematical odds of this happening, but I’m pretty sure they’re infinitesimal.  Most remarkably, this encounter underscores the tight migratory connectivity between Vermont and the DR, with 3 banded BITH now having been recovered between the two regions.  As I said, we’re still shaking our heads in amazement.

We can’t come close to topping that highlight from our second Mansfield field visit of 2014, but we again had a productive netting session, capturing 64 birds.  We didn’t manage to recover another geolocator from a Blackpoll Warbler, though we recaptured one male that had lost his (it happens).  Of 16 total Blackpoll captures, 11 were new birds (8 males, 3 females), 2 were previous year returns, and 3 were birds that we had banded last week.  We caught 15 BITH, one of them the cross-hemisphere champ, 4 other males that returned from previous years (2 from 2011, 1 each from 2012 and 2013), and 10 new birds (8 males, 2 females).  The only Swainson’s Thrushes we netted were 3 males banded last week.  Other noteworthy captures included a Yellow-bellied Flycatcher and a Red-eyed Vireo.

We’ll be back on Mansfield next week, wondering what avian surprises lie in store…

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