Rare American warbler surprises scientists

photo by G. R. Graves

photo by G. R. Graves

Apparently it doesn’t take much to surprise scientists ;), according to this headline. Hopefully, organisms adapting to, and taking advantage of, their environment is not new news. In fact, I seem to remember learning about “niche” theory back in the day, which suggested new niches that became available would be filled by creatures. But maybe that idea was promulgated so long ago that it has been forgotten? Or maybe creatures that are relatively rare are thought not to have these capabilities? Or thinking everything is “stunning” makes a better headline?

Here is the article from the Smithsonian that Steve Wilent posted in the SAF Linked-In site..

And here is one from the New York Times..

Swainson’s warbler breeding pairs require large territories of between 10 to 20 acres, which the pine plantations provide. Most warbler territories observed by Graves occurred in plantations planted on sandy loam soil, with normally low water tables, he says. “These pine forests may be creating a microhabitat at ground level where the birds feed on insects in the leaf litter, maintaining humidity and allowing them to live on dryer soils then they have traditionally.” Also, Graves observed, most plantations occupied by Swainson’s warblers had a certain “weediness,” associated with them: namely broadleaf saplings, vines and shrubs growing along the edges of roads and streams crossing the forests.

Covering some 40 million acres in the U.S. today, southern pine plantations are projected to increase to 66 million acres by 2060, Graves points out in his paper. “Given the 25 to 35 year rotation cycles commonly prescribed for private and commercial plantations, and a 7 to 8 year window of habitat suitability for Swainson’s warblers in a typical stand,” roughly one quarter of these pine plantations will be suitable habitat for these birds at any given time, provided that other requirements such as deciduous weediness and soil moisture are met, Graves concludes. “If current distributional trends continue, forestry lands managed for short rotation pine plantations will soon support a majority of the global Swainson’s warbler breeding population.”


  1. And the lesson for management is …. “sometimes we get lucky?”

    Some thoughts:
    Lots of birds have adapted to farming, too.
    “This behavioral trait is one not shared by the endangered Kirtland’s warbler (Setophaga kirtlandii) of Michigan’s jack pine forests which has rigid nesting requirements of small trees and open areas; or the Bachman’s warbler (Vermivora bachmanii), thought to be extinct,”
    What used to live where these pine plantations are now?

    • So Jon, luck was not the point I was trying to make. When you say “what used to live there?” it’s a complicated question.

      Suppose we had species a-e (I would use “a to z” with subscripts but I don’t know how to do that in WordPress) in the forests as managed by Native Americans in the South. Then it was changing over time after the Native Americans were moved out and was a function of how the stands had developed until then.
      ( There are better experts than I who read this blog who should chime in here!) , but some areas were planted and then grew back after farming, some areas were converted from longleaf, some areas were used for naval stores, some were in hardwoods but changed due to loss of American chestnut, so what was “used to be” has many different answers over the past 500 years or so and before..

      In some areas, we might have pine plantations with species f-l today, and then industry might sell them for housing or other development which contains species m-r. Whether a-e is “better” than f-l or m-r is a human value. But it has become a habit for people to value rarity rather than specific species, or specific species that are rare, because of the idea that we should “keep everything” a la Leopold and other trains of thought.

      With changes in climate, everything may have to adapt (given that most scientists think it is happening and too late to change).

      But we can’t know which ones will adapt and which ones won’t in advance, so we should take predictions with several grains of salt. Which I guess was the point of me posting this.. scientists should not be surprised when species do things they don’t predict because species and their interactions are more complex than we can understand (as per Haldane).

      • Thanks. I get your italicized point and agree with it.

        In trying to develop conservation strategies it became obvious to me that animals do not see the world the same way we do (sort of like seeing different wavelengths), and that makes it very hard for us to determine what they need or to predict where they will be. I’m not entirely comfortable crediting these warblers with a greater ability to adapt. I just think they saw what they needed in these plantations. So I don’t think ‘surprise’ should have been the point.

        My ‘what used to be’ question was really focused on the point that you get one thing at the expense of another, and you can’t really tell if this is a good thing without the whole story.

        I agree that ‘good’ is a point of view. But it’s more than a ‘habit’ to value rarity; ESA is a law. Maybe something that used to live here is now extinct. That would be a bad thing.

  2. Sharon, I think your comments about niche theory are still appropriate and relevant. Beijerinck said a long time ago, “Everything is everywhere, the environment selects,” and I teach my students that it makes sense if you think of “everything” as genetic potential for niche-filling (which I think is pretty much what you said). And so it makes sense that an environmental perturbation that might be undesirable for various reasons could still be serendipitously favorable to some otherwise threatened species; like Jon says, sometimes we get lucky. I’m not sure this makes a strong argument for short-rotation pine plantations, one way or the other, but it’s interesting, thanks for posting it.

  3. Oh and I forgot to mention…here is the “science” behind the EO Wilson quote about species loss in plantations based on my email exchange with him in 2002 (archived in my Lotusnotes)…apparently it was his “personal experience” that led to that conclusion.

    More on this exchange here on this blog in 2011 http://forestpolicypub.com/2011/04/24/roadless-fact-check-1/comment-page-1/#comment-13436:

    That’s why I asked EO what specific kind of plantation his estimates were based on.

    04/23/2002 01:37 PM To “Sharon Friedman/WO/USDAFS”

    cc ewilson@oeb.harvard.edu (Edward O. Wilson)

    Subject : Citation on loss of biodiversity from pine plantations- your statement in Mother Jones article

    Dear Ms. Friedman:

    It was a guess I made in a conversation, that then got into print. It
    can be straightened by simply taking out
    “estimates that a pine plantation contains 90 to 95 percent fewer species”
    and substituting
    “suggests that a pine plantation contains 90 percent or fewer species.”
    (I’ll lay money on that from personal experience.) And the “line of
    Wal-Marts” is OK.


    Edward O. Wilson


    Your message read:

    While researching for an article on views on pine management, I ran
    across a quote from you in a Mother Jones article, that stated “E.O.
    Wilson, a Harvard biologist and Pulitzer Prize winner, estimates that
    a pine plantation contains 90 to 95 percent fewer species than the
    forest that preceded it. He compares the effects of tree farms on
    biological diversity to “building a line of Wal-Marts.” .I would like
    to quote this in a paper I am writing on plantation forestry. Could
    you please give me the citation for your statement so that I can use
    it in my paper if it is from a paper or book or yours. If it was an
    interview, could you let me know what your thinking was based on
    (what tree farms you were talking about?).

    • Sharon, you’ll have to connect the dots a little more for me to follow what you’re saying… Where did E.O. Wilson come into this? I get that you’re reposting something you posted three years ago, about an email exchange you had twelve (?) years ago… but what’s the connection between E. O. Wilson and Swainson’s warbler? Did he make predictions about this bird? Or say something that contradicts the apparent resurgence of this one animal species? Sorry for being dense and not seeing how these things link up…

  4. Oh, sorry, Guy.. I guess I did skip a few things.. In the Smithsonian article was this quote:

    “Unlike natural forests with many different tree species of many different ages, pine plantations are monocultures of one species, all the same age and size and planted in evenly spaced rows. They were once described as biological deserts.”

    So how this is depicted is “scientists are surprised because they are not thought to be good habitat for critters (“biological deserts”) (however, we know deserts are really full of life and so on…) and yet are, in fact, good habitat apparently for a formerly rare critter.

    Now to say pine plantations (and of course they occur in a matrix with riparian areas and so on) are a “biological desert” where did that idea come from? Which reminded me of what was being said about them when I was writing a paper about plantations back in 2002 (refuting the idea that plantations were good for diversity, that was popular at the time, I remember a paper published by David Victor of the Council on Foreign Relations that struck me as not in touch with reality). It was published in this book “The Bioengineered Forest: Challenges for Science and Society edited by Steven H. Strauss, H. David Bradshaw.”

    As it turns out when I was writing a paper back in 2002, I was researching where that idea came from and one of the places cited E.O. Wilson. Being curious about what pine plantations he had used and what he had measured, I simply asked him because I couldn’t find any papers in the literature.

    Hopefully, this fills in the gaps.

  5. The “monoculture pine plantations” studied don’t look much like monocultures. Here’s the representative photo from the original paper. One wonders why the author calls this a “monoculture” (“Before the 1920s, large contiguous tracts of densely-planted, even-aged monocultures of pine were non-existent”).

    Come back in 10-20 years, and the pine will have shaded out the shrub and hardwood species. And the warblers will be gone, too.

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