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Three thoughts on the vagrancy of Tropical Turdids

July 29, 2010

What will likely be one of the more remarkable reports of vagrancy in North America this year was the discovery earlier this month of an Orange-billed Nightingale Thrush in the Black Hills of South Dakota.  There are several reasons why this individual sighting was noteworthy, besides the novelty factor which was significant, and in considering this bizarre record, three things came to my mind and as they’re somewhat unrelated to each other and I’m not in the mood to write segues, they’re going to come at you in near bullet point form.  It’s up to you as to whether you want to catch them in your teeth.


I guarantee that the first thought had by many birders upon hearing the news of the Nightingale Thrush was, “How the heck did that bird get there?”.  Orange-billed Nightingale Thrush is a pretty common bird across Central America (I’ve seen them both in Guatemala and Costa Rica, more traveled birders have certainly seem them everywhere else) and reaches the northern terminus of its range in Tamaulipas, Mexico, not more than 250 miles south of Texas.  Even so given it’s proximity, it’s only been found in the US two times before, in 1996 and 2004, and it wouldn’t surprise you to know both of those records are from the Lower Valley.  Lots of birders plus adjacency to Mexico equals fabulous and surprising birds.  It always has.

So why did the third record of the species in North America become a wild outlier for Central American species in the US?  Who knows?  Those previous records were considered to be spring migrants overshooting their regular range, and while that might explain a couple hundred miles, this bird went another 1500 miles farther.  Across four states.  In mid-summer.  This species is known to occasionally be taken for the pet trade, but I hadn’t heard that this individual showed any wear suggesting it had a caged past.  So there’s a good chance it’s a legitimately wild bird, which immediately prompts the question of whether this sort of extreme vagrancy is just a freak occurrence that one birder was lucky to put himself in the right place at the right time, or is vagrancy in this part of the continent more regular than we know because the panhandles of Oklahoma and Texas, along with western Kansas, Nebraska, and South Dakota are significantly underbirded?


When a mega rarity is found anywhere on the continent, the twitcher yen starts to pull at your psyche.  Soon after, the “twitchers are bad for birding” folks come out of the woodwork.  I’m fairly ambivalent about chasing rarities, mostly because I’m guaranteed bad luck when it comes to finding vagrants (my batting average, as it were, is well below .500), but I don’t begrudge the odd birder the thrill of the chase.  The bottom line is that it’s fun, and I figure the amount of good work I try to do for conservation in my local community and the general “green-ness” with which I try to live my life cancels any carbon demon I might incur on the rare occasion a good bird calls to me.  I think most birders can say the same.  Besides, that part of the continent doesn’t really get much in the way of awesome drop-everything vagrancies, so if they chased it, I hope they got it and had a good time doing it.  I know some folks definitely did.


Last, the bird itself was discovered by a fellow bird blogger, Eric Ripma, and the report distributed on his blog.  This is the most exciting part of the story for me, as I’m a big advocate of the nature blogosphere being a platform to not only to share and distribute rare bird sightings, but to report them in the first place.  This is something that is only going to be more prevalent as technology pervades even our time in the field.  I know there are plenty of folks that shudder at the prospect, as if something essential is being lost with the incursion of technology.  In the sense that birding and nature study is a way to pull away from the epidemic omnipresence of modernity in what is, in many ways, a pastoral 19th century pastime, I get that.  I do.

But the currency of the modern world is, beyond any doubt, information itself, and I can’t help but be excited when news of this magnitude is proliferated this way.  I’m strongly of the belief that the more information that is made as widely available as possible the better it is for birding, bird science, and bird conservation. In a practical sense, this means more reports like this Nightingale-Thrush, which besides simply being fun whether or not you decide to go after the bird, lead to more and better information about distribution and abundance for those who are pushing the horizons of our understanding of birds.  Information that, in turn, is disseminated back through the internet bird community in a feedback loop that lifts us all.

To be a good birder still takes the experience that can only be gained by time in the field.  That will never change, and we’re all better for it, but the barrier for entry is much lower, the starting point much closer, than it ever has been.  This is a great thing, and the bird blogosphere has a lot to do with that.  It’s a real sea change in the way we think about our hobby.  One for the better I say, but I imagine I can be considered sort of biased.

Oh yeah, some photos of the bird can be found here.  As of yesterday it was still there, singing away. Really cool stuff.

  1. July 29, 2010 8:51 am

    Well said, Nate.

    I admittedly tend to be somewhat jaded when it comes to vagrants. Not because I don’t care, but because I live in Texas. Just this past winter into spring we had a bare-throated tiger heron, an Amazon kingfisher, a northern wheatear, one or more roadside hawks and a northern jacana (plus a few others I can’t immediately remember). Right now we have sooty terns, tropical kingbirds and a few other notables. Being so close to so many species (I think the official state list is >630) means either running all the time to see the latest rarity or accepting that there’s always going to be an interesting bird to see somewhere in the state and you have to pick your battles wisely.

    I mention all that because more and more I don’t think of these as cases of extreme rarity so much as cases of more people looking and technology making the information available pretty much in real time. Nature doesn’t care about formal ranges; that’s a hang-up we have. Sure, there are going to be real vagrants that are exceptional, yet I feel those will become less frequent as we realize these happen all the time and people are just now taking notice with the ability to spread the word immediately.

  2. Nate permalink*
    July 29, 2010 9:53 am

    @Jason- Texas is phenomenally birdy, just jaw-droppingly so, and for the most part those birds are accessible too. The continent scale vagrants we get in NC are almost exclusively pelagic so there’s already a sort of circumspect attitude with regard to them. But I can imagine almost getting worn out by reports in TX and just deciding to miss some.

    I think you’re pretty right on about the advent of technology making these sort of records available in real time in a way that we haven’t had before and what that means. It’s going to make us rethink our concept of vagrancy and how prevalent it is. I think birders are pretty good at finding what vagrants are present because birds are often present at predictable places, even vagrants to some extent tend to show up in places where there are lots of birds which are, of course, places where birders go. But a record like this one can completely blow that theory out of the water, or at the very least, cause us to re-evaluate our notion of what places are “birdy” and how those patterns play out on the continent. I think that stuff is fascinating.

  3. July 29, 2010 10:41 am

    I learned about that bird yesterday by reading
    Robert Ake’s big year blog ( Hope he finds the bird today!

    Chasing the bird would be fun…..but wouldn’t be more cost efficient (not even talking about environmentaly responsible) for us mortals with limited traveling funds just to go in central america once every 5 years, to see those birds in their original habitat, instead of twitching multiple time across the continent to bag 0.5 bird per trip (assuming you’re batting average is normal)? tha’ts my approach to birding, at least.

  4. Matt O'Donnell permalink
    July 29, 2010 11:16 am

    I was in the Black Hills doing some paleontology research the past two weeks and heard about it from Gene Hess, a Delaware bird expert recently relocated to South Dakota. His hypothesis was that the Nightingale-Thrush got caught up with wintering Veeries and other thrushes in Mexico and migrated north with them. This bird may have been around since May. The bird’s behavior has changed significantly over the week it has been seen, so perhaps it is a new arrival.

    Spearfish Canyon is a beautiful part of the Black Hills to visit even if you don’t see the bird! I missed a view of it by about 10 minutes (typical) but heard it sing many times during the hour I could spend there.

  5. July 29, 2010 3:39 pm

    Yes, it was exciting to see how quickly the news of this interesting case of vagrancy spread over the net via a birding blog! Definitely- the more information the better for bird conservation and birding.

    Since the bird doesn’t appear to have been kept in captivity, the idea that it may have migrated with wintering thrushes in Mexico seems like a fair possibility. Support is shown for this when one takes into consideration that all other Catharus species that breed in North America probably became established there as a result of their ancestors migrating from the neotropics. Although Orange-billed Nightingale-Thrush is not placed within the group of Catharus species that breed in North America (all North American breeders and two highland species of Mexico and Central America), it is still grouped in a genus of birds where long distance migration appears to have evolved on four separate occasions so maybe vagrancy such as this (albeit rare) shouldn’t come as a huge surprise. I don’t think this means we should expect a big increase in sightings of this species far north of its typical range (although that would be really cool!), but that perhaps we can expect to see very occasional vagrancy of resident neotropical bird species that are related to boreal migrants (such as various warblers, vireos, thrushes, etc.). I am guessing that the frequency of such occurrences would be far and few between but maybe we will get a better idea of how often they occur with more birders out in the field who post their findings online.

    For more information, see the insightful paper by Kevin Winker and Christin Pruett that investigates migration, speciation, and morphological convergence in the Catharus thrushes at

  6. July 29, 2010 5:56 pm

    The idea that the nightingale-thrush traveled north in the company of other birds that winter in the tropics makes sense to me. I wouldn’t be surprised if Central American vagrants made this trip regularly. The center of the country has a lot fewer birders per square mile than the coasts, so a lot of rarities may go unnoticed.

  7. July 29, 2010 6:18 pm

    I first learned about the nightingale-thrush through a Facebook post by Christopher Taylor
    I think all this digital age birding is great! I’m quite certain that many “old school birders” would have used blogs/ Facebook/ iPhones if they had them. Thanks for your 3 Thoughts!

  8. David Morin permalink
    July 29, 2010 7:23 pm

    I wonder if there was some weather pattern that pushed normally very southern species northward in the spring migration because up here in Canada there is a Black-bellied Whistling Duck in Ontario right now, a bird also from the south and it has stayed pretty much the entire summer.

  9. Nate permalink*
    July 29, 2010 9:55 pm

    @Laurent- That guy gets around! If you want to be guaranteed to see OBNT, go to Central America. It’s a sure thing. But I have to say, even as someone who’s seen it before, there’s something about it being in South Dakota that is so appealing.

    @Matt O’Donnell- You’re probably right, I’ll bet the bird has likely been around for some time. Eric Ripma was just the lucky guy to come across it first. Good for him!

    @Pat O’Donnell- Two O’Donnells! The odds of that have to be about the same as a OCNT in South Dakota! A fascinating paper, though I only read the intro and discussion. The center of Catharus diversity is definitely in the central Mexican highlands, but given the recent study that suggested neotrop migrants evolved in North America prior to the isthmus, I wonder if the non-migratory Catharus thrushes, like the OCNT, speciated before or after the highly migratory ones came along, or at what point between the four separate incidences of long-distance migration evolution.

    @John- I suspect you’re right. Birders in the western great plains have an incentive to keep their eyes open year round now.

    @Anne- I couldn’t agree more about the use of technology.

    @David- I wondered that same thing, and looked to see if there was a strong southerly push in the week before the bird was found. But if it has been here since May, as some suggest, it would be hard to know which one brought this specific bird since so many birds are moving at that time of year.

    • July 30, 2010 7:50 pm

      Yes, I think you are correct about the odds of us two O’Donnells commenting on the same post!

      I would love to see that paper- been searching for it with various keywords but have come up with a handful of “nada”. Do you happen to know the title, piece of the title, or a link to it?

      It appears that the OCNT evolved from a common ancestor shared with three other non-migratory”orange-billed” NTs (Black-headed, Slaty-backed, and Spotted) after long distance migration had evolved in the Wood Thrush (the apparent greatest grandaddy of the Catharus thrushes) but before the North American migrant Catharus species evolved.

      Or in other words, after the first time long distance migration had evolved with the Wood Thrush but before the second time this had evolved with the Swainson’s Thrush (although maybe the ancestor of the Swainson’s Thrush kept the migratory behavior of the Wood Thrush while the ancestor of the OCNT group lost migratory behavior).

      In any case, I have been conundruming myself in trying to figure out which scenario was more likely- this group of birds evolving in the neotropics or in the boreal zone and have come to the conclusion that the answer is going to elude me so I better go do something else like make a pizza or look at photos on Surfbirds.

      • Nate permalink*
        July 30, 2010 8:00 pm

        The press release with info is here. I don’t know if the actual study has been published yet, it just came out this month.

        They used some molecular data and phylogenetics to suggest that neotropic migrants evolved in North America and colonized South America. Now whether this directly involves the Catharus thrushes I don’t know, since “North America” technically includes Mexico and most of the northern part of Mesoamerica too, but the conclusion seems to be that migration evolves towards off-season survival rather than new breeding success. Though, as always, more study is needed.

        It’s cool stuff.

  10. Ottavio Janni permalink
    August 4, 2010 12:06 pm

    The abstract of the paper, which was published in Ecography, is here:

    You need access to blackwell to download the pdf (depending on where I’m working, I sometimes have access, but not right now)

  11. Nate permalink*
    August 5, 2010 12:12 pm

    @Ottavio- Great! Thanks much!

  12. August 7, 2010 9:32 am

    I had these thoughts to share on the ABA yesterday and would incorporate much of the above in the marketing plan were I writing it. (My original post appears not to have gone through so I’m repeating this — full comments on my blog; link below.)


  1. Alan S. Hochman Photography

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