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CWS_BigBlue(WR)_lg.jpgNotes from the Canyonlands

Chuck has retired but
his past blogs are still wonderfully entertaining.

Occasional observations and notes from Dr. Chuck Sexton, the wildlife biologist at Balcones Canyonlands National Wildlife Refuge.  Chuck has been on staff at the Refuge since 1994 and has been a student of the ecology of the Texas Hill Country for over 30 years.

*** Be sure to click on the "Read more" button to see the full text of each entry!
***The public can read Chucks posts, but only dues paying members (logged in) can comment.
  • Monday, May 03, 2010 5:25 PM | Anonymous

         Our 10th Balcones Songbird Festival, Friday-Monday, April 23-26, was an unqualified success with great attendance (over 500 people!) and a great array of birds. Despite some windy afternoon conditions, all of the target tours got looks at both Golden-cheeked Warblers and Black-capped Vireos. A total of 108 species of birds was reported in the Refuge area for the four days of the festival. We had a smidgeon of migration of some raptors, waterbirds, and passerines but no concentrations or fallout. Interestingly, the festival bird list started and ended with two of the rarest sightings. Tour guide Judy Bell woke up Friday morning to photograph male Lazuli Bunting at her trailer pad near the HQ, one of fewer than a half dozen reports ever of that species here. (See a link to her blog below.)  Then literally the last species added to the list on the last tour on Monday morning was a flyover of about 30 White-faced Ibis on RM 1174 just north of Doeskin Ranch--the first confirmed report of the species for the Refuge. Ironically, the ibis were spotted by participant Don Robinson (I hope I got that right), who purposefully left his binoculars behind so that he could just "look around and enjoy all the diversity" to be found on the tour. Thanks, Don, and thanks to Jim Baines for capturing that flight in digits! Below are some avian highlights:

         White-faced Ibis (flyover of 30 on RM 1174 just north of Doeskin Ranch)

    Part of the flock of White-faced Ibis overhead.  Photo by Jim Baines, used by permission.

         Mississippi Kite (a few singles and flocks)

         Northern Harrier (two singles, a bit late)

         Peregrine Falcon (4/25 at Eckhardt)

         Barred Owl (Simons oak savannah)

         Yellow-bellied Sapsucker (4/24; very late)

         Vermilion Flycatcher (brief sightings on Saturday)

         Black-capped Vireo (cooperative birds at Russell tract -- a CLOSED tract)

         Yellow-throated Vireo (nest near HQ over Post Oak Creek)

         Common Raven (young being fed in nest on Cow Creek)

         Cave Swallow (active colony on 1174 just N of Doeskin Ranch)

         Blue-gray Gnatcatcher (nest building on Post Oak Creek)

         Golden-cheeked Warblers (many areas; having a good year)

         sparrows - 12 species, but missed Canyon Towhee and Black-throated Sparrow

         Lazuli Bunting (one male seen twice on 4/23-24; photographed by Judy Bell)


    Judy Bell's Lazuli Bunting - 1st photo documentation for Refuge


         Painted Bunting (barely arrived in time for festival, but soon abundant)

         Yellow-headed Blackbird (one male posed at Flat Creek Winery, Friday evening)

         [Great-tailed Grackle - missed. Woo-hoo!!]

    A few of the other conspicuous bird misses during the festival:  N. Bobwhite, Crested Caracara, Rock Pigeon, Common Poorwill, Belted Kingfisher, Orange-crowned Warbler, Dickcissel, Eastern Meadowlark, Baltimore Oriole.

    Our list of herps (amphibians and reptiles) included:

         Blanchard's Cricket Frog

         Gulf Coast Toad

         Green Anole

         Texas Earless Lizard

         Red-eared Slider

         Texas Cooter

         Western Coachwhip

         Redstripe Ribbon Snake

         W. Diamondback Rattlesnake

    The short mammal list (not counting road-kill carcasses) included Eastern Cottontail, Black-tailed Jackrabbit, Coyote, and White-tailed Deer.

    The wildflower display and the butterflies were just eye-popping all weekend. (See, for example, Dwayne Litteer's gallery at the link below.)  Thank you, Mother Nature!

    If you were at the festival and would like to provide a link to your photos, please send the link to me and I'll add it below.

    --  Check out Judy Bell's blog, 'Travels with Emma' with photos of the Festival in her April folder on BlogSpot.

    --  See more of Jim Baines' photos from the Festival on his BetterPhoto.com page.

    --  Dwayne Litteer's extensive gallery of photos from this year on SmugMug.com.

    --  A news story on the Festival in the North Lake Travis Log.

  • Saturday, May 01, 2010 2:00 PM | Anonymous
    This blog ISN'T really R-rated...see below.     Well, maybe I'm exaggerating in this headline to grab your attention.  But in truth, on April 9, I had arguably the rarest wildlife encounter in my 35 years of professional wildlife encountering.  On that morning, Elizabeth Lesley and I were censusing Golden-cheeked Warblers in our Rodgers Southeast Prime Warbler Study Area, a rugged 100-acre patch of ankle-twisting, knee-popping terrain in the heart of the Refuge.  We had hiked down a steep ravine, following the sounds of territorial male Golden-cheeks as we scribbled notes on our field maps.  Towards the bottom of the ravine, I heard a harsh chattering noise that I couldn't identify; that's a rare event in itself, but that's not what I'm talking about.  I assumed we had startled a fox squirrel, a raccoon, or some other small critter, but the sound emanating from up in the tree was just...strange.
         After a minute, I finally spotted the species which was making the ruckus: A Ringtail (Bassariscus astutus):

    A Ringtail high in a tree.

         The Ringtail, sometimes known by the misnomer "ringtail cat", is a lithe relative of the Raccoon and the Coati.  They are strictly nocturnal and very shy.  Encountering one in the daytime is quite unusual.  I had only had this experience about three times previously, even though I have probably seen a total of 12 or 15 Ringtails in my career.  Rare enough, but nothing to write home about.

        In fact, there were *two* Ringtails in the tree.  On all the nighttime spotlight surveys we've done, I can't remember ever seeing two in the same tree.  I recall we once had three or four in one survey, but they were scattered all along that particular route.  So, two Ringtails in a tree in the daytime: Very unusual, but that's not the rarest part of the observation...

        They were...how shall I phrase this delicately...beginning a family together.  After we initially interrupted their activity, they had relocated to a different treetop and the X-rated show restarted.  From their new vantage point, the female was peering down on us and uttering what I assume was some type of alarm call.  Her partner, with the typical short attention span of a courting male--of any species--was thoroughly focused on her.  I managed to take a few distant pictures of the event with my little camera and actually recorded a 30-second soundtrack of the alarm calls and love chatter.  I'm limiting my posting of that documentation out of a sense of discretion; it will remain available for future study in the "Refuge files".

    The cute couple, begging for some privacy:          

    To paraphrase the ever-subtle Shakespeare,
          here is a "two-tailed ringtail":

    * By the way, in case you were wondering, the "R" rating is for "Rarity", "Rodgers", "Rugged", "Ringtail", or "Ruckus"...take your pick.  This blog has been rated "PG" by the Balcones Canyonlands Blog Rating Association.
  • Sunday, April 04, 2010 4:26 PM | Anonymous

         I'm going to just slap a bunch of images in here from the past few weeks Interior Secretary Salazar with Chuck and Deborah.with some brief remarks about each set.  These will include, in no particular order: (a) Interior Secretary Ken Salazar, (b) photos of the early 2009 prescribed burn on the Rodgers tract and recent pictures of its recovery (pretty wildflowers, etc.), (c) some recent scenes from Post Oak Creek (sunrise, swimming hole, etc.), (d) images of a recent Hutton's Vireo detected on the Beard tract in late March, and (e) a menagerie of recent critters, many of which--particularly the collection of moths--were photographed at the porch light at nights at the Beard cabin.

        Just to prove I wasn't telling tall tails about the visit from a dignitary from Washington, D.C., here is proof of Secretary Salazar's visit.  We took a 45-minute walk in the late afternoon of March 11 along the Cactus Rocks Trail.  Frequent trail users will recognize the tilted (broken) juniper limb over our heads (at marker #9).

        In 2008, we began the heavy-handed process of restoring some shinnery habitat for the Black-capped Vireo on several tracts.  This initially involves crushing the scrubby 2nd-growth cedar and the standing shin oak, then running a prescribed burn through the resulting heavy slash.  This kind of fuel load can produce a VERY hot fire--don't try this at home--but we have learned that this is precisely was is necessary initially to start habitat on the best trajectory for the vireos.  Here's what a prescribed burn on the Rodgers East Plateau and its aftermath looked like in January 2009:

    Prescribed burn on the Rodgers plateau in January 2009.  Rodgers plateau after the burn.

        The response of a Hill Country landscape even after a very hot burn like this is nothing short of miraculous.  All of the native perennial grasses and shrubs, as well as native trees such as oaks (3 species), Texas ash, cherry, and cedar elm have regrown vigorously in 2009 (a severe drought year) and the beginning of the current growing season.  The robustness of many of our native wildflowers is stunning on the new open ground:

    Rodgers plateau in late March 2010.  Another view of Rodgers plateau burn unit in late March 2010.

    Golden Groundsel in the burn unit.  Prairie Verbena responds vigorously on the burn scar.  Robust growth of Dewberries and Heller's Marbleseed in the burn unit.

        Here are some recent shots in the Post Oak Creek watershed.  A sunrise, a new-found swimming hole--er, I mean, natural pool, and a tenacious old juniper that refuses to let go of it's cliffside perch:

    A natural pool on a side branch of Post Oak Creek--not even the main waterway!  A tenacious juniper holds onto a cliff by it's 'toenails'.

         When I encountered the Hutton's Vireo on our Christmas Bird Count last December, I was happy to have added another record of this rare vagrant to our avian database.  Then on March 25, remarkably, I heard another Hutton's Vireo singing on the Beard tract--eight miles away from where the December bird had been detected.  Was this the same individual or another?  We'll never know.  But this one was for certain a male; he was vigorously "singing"--and I use the term loosely when it comes to this species.  I managed to get better photos this time and also used the "movie" function of my point-and-shoot camera to actually get some good recordings of several different songs of his.  He hung around at least a few days; I heard him singing again on March 27 in the same area.  Here are two cropped pictures from the 25th.

      Hutton's Vireo on the Beard tract, March 25-27, 2010.

        With the good macro capabilities of my little camera, I have the opportunity to get very identifiable photographs of many insects.  Actually identifying all the critters takes longer, so right now I'm just pointing and shooting at everything.  The identities will come later.  Here is a typical menagerie which can show up at the porch light on the Beard tract, followed by a gallery of various creatures.  I've put tentative names on some of the moths; hover your mouse over an image to see my notes.

    Beard porchlight menagerie.

    A strange fly. Ichneumon wasp. Ladybird beetle

    A colorful Noctuid moth. Snowy Urola Note the pattern of dark marks.  I call this the 'JC Moth'. Diastictis fracturalis; a pyralid moth with silvery spots. Phytometra orgiae; a small yellow and pink Noctuid moth.
    Unidentified moth. Tarachidia candefacta; known by the very descriptive name of 'Olive-shaded Bird-dropping Moth'.

    A wall of confusing look-a-likes; I'm quite certain these are seven different species in two families:
    Isturgia dislocaria; a Geomtrid moth.Unid moth3.Unid moth4.Unid moth5.
    Unid moth6.Maybe Diagrammia atrafasciata, a Geometrid.Unid moth8.

    Finally, a number of people mentioned that they encountered a widespread "hatch-out" of the beautiful Polyphemus moths in late March.  One or two showed up at the Beard porch light, dwarfing all the other visitors:

    Polyphemus moth, with conspicuous 'eye-spots'.

    * * * * *
    Below the Line:

         Here are a few recent "visitors" to the Refuge who were, for obvious reasons, ushered off the premises:

    'Hereford today, gone tomorrow.'
    Trying to 'steer' clear of an irate Wildlife Biologist.

  • Wednesday, March 17, 2010 10:32 AM | Anonymous
         I'm now entering the most fun time of year--the beginning of our field season.  While I will still have office duties to accomplish, and so many unfinished reports, it is at this season that I can justify spending more time in the field chasing down warblers, vireos, and everything else under the sun.  Given the season, this blog may morph into something more episodic and less philosophic.  The bad news is that I may have infrequent opportunities to spend time uploading stuff; the good news is that I begin at this time of year to accumulate a lot of documentation for biological resources...and other interesting tidbits...all over the Refuge.  To this end, this beginning-of-season entry will constitute a miscellaneous collection of images from the past week or so.

        The flowers to the left are those of Texabama croton, one of our rarest and earliest blooming shrubs.  Goatweed_egg.jpgThese crotons begin to bloom about the same time we see the first blooms of spring herald (Forestiera pubescens) and agarita (Berberis trifoliolata).  Like most of these early flowering shrubs, the croton is a very good butterfly plant at this season.  The Great Purple Hairstreak which graces our regular Refuge brochure is nectaring on Texabama croton flowers.  Crotons, however, like many other plants in the Euphorb family, are not eaten by much.  The shrub is amazingly immune to deer browse.  To date, we have only documented one species of butterfly which utilizes the foliage as a larval food plant, the Goatweed Butterfly.  ("Goatweed" is a common name for several other species of croton.)  On our initial field excursion this past Monday afternoon, Elizabeth Lesley and I watched a female Goatweed Butterfly lay a single egg under a croton leaf:  

         Arch Rock.  As I scouted for Golden-cheeks last week on Warbler Vista, I came across this rock formation which had separated from the adjacent rimrock.  It is a natural arch rock with the opening about 3 ft tall and 8 ft wide.  Here are three shots of the feature from different angles.

    Arch_WV_E.jpg Arch_WV_back.jpg Arch_WV_front.jpg

         Huge Cave and Stream (?).  On the same hike where I encountered the arch rock, I stumbled into this cavern which has a spring-fed stream issuing out of it.  The entrance is 14 ft high and it goes back probably 50 ft or more.  The stream varies from 8 to 10 ft across.  An amazing location:


    (Oh, did I say "feet"?  I meant "inches".
    I was crawling on my belly under the 14-inch high ledge to squeeze in and get a picture of this spring-fed stream [really] which is about 8 to 10 inches across.
    I apologize for any excitement I may have
    inadvertently caused.)

         Critters.  Spring has sprung.  Along with the Goatweed Butterfly documented above, Amer_Lady_cat.jpgElizabeth and I also found this fancy caterpillar munching on rabbit-tobacco (Evax prolifera).  This "cat" will turn into an American Lady butterfly. 

         Things on the ground are always more likely to catch our attention, even when censusing Golden-cheeked Warblers.  The importance of always watching where you put your feet while hiking in the hills is self-evident to every Texas biologist, rancher, and adventurous child.  (Poking your eye on a juniper twig is an added adventure which requires that all warbler biologists have simultaneous "tri-focal" attention--up, down, and straight ahead.)  After Elizabeth and I had finished our warbler work and were on our way out of the study area Monday, I began turning over flat rocks to see what might be lurking underneath.  I was rewarded with a close encounter with the season's first Texas Patchnose Snake, documented by Elizabeth while my hands were quite literally tied up by this cute little constrictor.

    Patchnose Snake.jpg   Patchnose_face.jpg



  • Tuesday, March 16, 2010 5:32 AM | Anonymous

        Two visitors--whose names I failed to get--reported the first Golden-cheeked Warbler of the season on the Refuge on Monday morning, March 15.  They saw a male warbler near trail marker 4 on the Cactus Rocks Trail at Warbler Vista.  Later in the afternoon, Elizabeth Lesley and I hiked into our Rodgers Prime Warbler Study Site and found two male warblers.  Whew!  Spring is officially here.

    * * * * *
    Below The Line:

         I tend to visualize just one thing when I use the abbreviation "GCWA".  However, away from the juniper-oak woodlands of the Texas Hill Country,
    the world is not so constrained.  Some time ago, I was doing a search for articles on the Golden-cheeked Warbler and happened to type this standard four-letter abbreviation into a search engine.  That led me on an interesting diversion.  Between Google, Yahoo!, and acronymfinder.com, I learned of the existence of many concepts and organizations I never would have dreamed of.  Not surprisingly, a great many are on the Gulf Coast; among these are:

         Gulf Coast Wakeboard Association [Which owns the domain name "gcwa.com".]
         Gulf Coast Water Authority
         Gulf Coast Woodturner's Association
         Gulf Coast Writers Association
         Gulf Coast Wrestling Alliance

    But the collection of associations was farther flung than just those.  Witness:

         Gastonia Community Watch Association [Gaston Co., NC]
         George's Creek Watershed Association [Allegany Co., MD]
         Georgia Cattlewomen's Association
         Georgia County Welfare Association [Covington, GA; owns the domain "www.gcwa.us"]
         Gills Creek Watershed Association [Columbia, SC]
         Greater Charlotte Workroom Association [Charlotte, NC]
         Grey County Woodlot Association [somewhere in Canada]

    Even farther afield, I found:

         Gliding Club of Western Australia


         Global Championship Wrestling Alliance

    In the realm of science, I found:

         Gilford fine sandy loam, 0 to 1 percent slope [Pulaski Co., IN]

    and I have no idea where they came up with "GCWa" for that.  However, my all-time favorite has to be:

         Generalized Closed World Assumption

    This has something to do with "Disjunctive Logic Programs and Deductive Databases", to wit:

         "The closed world semantics defined above is the "strongest" negation semantics possible for disjunctive logic programs based on minimal Herbrand models and is known as the generalized closed world assumption (GCWA)."

    I'm glad I could clarify that for you.

  • Wednesday, March 10, 2010 9:41 PM | Anonymous
         Yes, I know, I'm letting my Disney show through*.  But rather than conjuring up a White Rabbit, I'm actually trying to entice home a small bird with bright golden cheeks.  

         As of this afternoon (5 p.m. on March 10) we had not detected a Golden-cheeked Warbler on the Refuge.  I've confirmed through emails and the TexBirds discussion list that the warblers are arriving in the Texas Hill Country.  Ingram_GCWA_Worm.jpgA birding friend out west of Kerrville heard one outside of his office window on Monday, March 8, at about 3:45 p.m., the first report for Texas this year.  At least one was heard in Uvalde County on the 9th, then today there are reports of Golden-cheeks from both San Antonio (to our south) and Fort Hood (to our north).  Most of these observers remarked that these first dates are "a little later than usual", which opens up an intriguing topic of discussion: Are migratory birds changing their habits and migration patterns with long-term environmental changes?

         Traditionally, March 12-13 had been considered the expected arrival date for Golden-cheeks in the Hill Country, compiled by Warren Pulich from decades of observations up through the mid-1970's.  Since the publication of Pulich's work, more and more observers (the cause?) have been reporting Golden-cheeks progressively earlier and earlier (the outcome?).  Just a few short years ago, I would have recited March 8 as a more likely first date of observation (by someone somewhere on the breeding range).  Most recently, at the risk of speaking for a large group of researchers, we have been only mildly surprised when first reports of the species came on March 4th, 3rd, 2nd, etc.  In 2008, Mark Gray established the first February record of a GCWA in Texas with his observation of one arriving in Austin on February 29--but that's sort of cheating since it was a Leap Year.  Then came Spring (?) 2009 with a report by Heidi Trudell and Matt York of a male GCWA at Meridian State Park on the "ridiculously early" date of February 27.

         It is just so easy and--with apologies to the former Vice President--so convenient to suggest that changing climate patterns on a continental scale may be enticing Golden-cheeks to arrive earlier and earlier.  While that may be the exact, correct answer--if/when we have sufficient data to confirm the pattern--it is crucial to keep in mind that patterns in Nature are never simple.  There is variation upon variation.  Going back to my surfing analogies, the patterns of changing migration dates, when plotted over time, will begin to look like irregular ripples on top of larger swells, which may or may not have an underlying long-term direction of change.  It will look as sloppy as the chart you'd see when plotting long-term rainfall patterns or, gulp, stock market trends.  Here are three charts illustrating real world data.  One might be rainfall, another the stock market, another may be migratory dates--It's not really important.  The nature of *data* is the point I'm making.


         Let me quickly say that I am *not* a skeptic when it comes to climate change.  We are doing bad things to the global climate and we are seeing symptoms of that in a great many natural history disciplines.  Our focal Golden-cheeked Warblers may--just may--be reflecting those directional changes by what we are observing in arrival dates here on the breeding range.  It is a wonderfully complex topic to consider what landscape level cues the Golden-cheeks are reponding to; that would be worthy of a couple of Ph.D. dissertations.  The present blog is just prompted by the curious and perhaps unexpected warbler timetable we are seeing this season.  Last year, they were very early; this year, they are late--by their own standard set in recent years.  But today's "late" was yesterday's "early" in a normal year.  Have I cleared this up sufficiently?

         This topic could not be more timely nor more geographically appropriate:  ken-salazar.jpgSecretary of the Interior Ken Salazar will be in Austin on Thursday, March 11 (perhaps the day you are reading this blog) to roll out the latest edition of the "State of the Birds Report", compiled from diverse sources.  This year the report will emphasize the challenge of climate change to the conservation of migratory birds.

         In the meantime, I've got to get some rest.  It will be an early day for me tomorrow--out to the Refuge to try to rope in a Golden-cheeked Warbler to show the Secretary and our other visitors.  No pressure!  [I am happy to take responsibility for my own actions, but when it comes to predicting the weather or the occurrence of migratory songbirds, I relinquish any responsibility for those events!]

    * * * * *
    Below The Line:

    *   I hope I am clear on the difference between Lewis Carroll and Walt Disney.  From my recent research, I learned that the famous "I'm Late, I'm Late..." ditty popularized in the early Disney feature of Alice in Wonderland is a paraphrase of the same concept uttered--in different words--by the rabbit in Carroll's novel.

         Credit for the White Rabbit thumbnail is as follows: "The White Rabbit, illustration from Alice in Wonderland by Lewis Carroll 1832-98 adapted by Emily Gertrude Thomson, 1889, a painting by John Tenniel."  The beautiful Golden-cheeked Warbler male is one of my favorite John Ingram images--Thanks, John.  The charts are ripped from random sources via Google Images, stripped of identifying legends on purpose.  The pic of Secretary Salazar is, I believe, his official portrait as a member of the U.S. Senate, prior to his appointment as Secretary of the Interior.

  • Sunday, March 07, 2010 8:39 AM | Anonymous
         A few weeks ago, a small team consisting of myself, David Maple, Elizabeth Lesley, and Jean Nance hiked to those big junipers I had reported earlier in the Post Oak Creek watershed ("The Wonderland of Post Oak Creek", Feb. 10) to get some good measurements on the trees.  I report the results below, but first I thought it might be instructive to describe how big trees are measured.  The answer: "...with difficulty."

         There are a number of technical points on what constitutes a standard--or official--measurement of a tree.  The best starting point for learning about this is on the Texas Forest Service's website for the Texas Big Tree Registry.  At that site you can learn "How to measure a big tree" and the details of the "Measuring rules".  You can also view or download the "Registry of Champion Trees" and a nomination form, if desired.  Lifted directly from their information, here is an overview of how to measure a big tree:

    dbh point.gif     The starting point is the "DBH point" which refers to the "diameter at breast height" and is defined as 4.5 ft above the ground level.  Rather than using the diameter of a tree, the size is actually gauged on the circumference of the trunk.  This is "the smallest circumference between the DBH point (4.5 feet) and the ground, but below the lowest fork."  As you can imagine, there are complications for multi-trunked trees, leaning trees, trees on slopes, etc.  The TFS website explains what to do in those circumstances.  For big tree measurements, the TFS uses English units of measure; the circumference is reported in inches.

         The height of a tree, of course, is an integral part of the calculation but this can be the trickiest part to measure, especially in a heavily wooded setting.  I discovered that my "ocular estimates" reported previously ("50+ feet") were too generous.  If you believe all the botany texts, properly measuring the height of a tree would seem to require an advanced degree in mathematics with an emphasis on trigonometry.  Height_stick_method.gifLuckily, there are any number of modern forestry tools to accomplish the task of sizing up a tree.  Unfortunately, we had none of those at hand, so we used a modified version of the "stick method".  (Lest your imagination run amok, yes, we did the subsequent calculations on an abacus and dutifully recorded the data on a clay tablet...)  By this, you have some standard reference height positioned at the tree (a person of known height, or a pole of known length).  Then, you back off a substantial distance and use some calibrated "stick" (in our case, a standard 12-inch ruler) to gage the relative height of the tree versus your measurement standard.  Got that?  For instance, while Elizabeth Lesley held up a 3-meter pole at the trunk of one big juniper, I stepped back until I could match the 3-meter pole with the 3-inch mark on my ruler.  The top of the tree happened (by coincidence) to match the length of the ruler exactly--12 inches--so some easy math allowed me to determine that the tree was 12 meters tall.  Converted to English units, that is 39.4 ft, which by the TFS rules is reported as 39 ft tall.

         The last measurement of a tree which goes into the formula for its score is Average Crown Spread.  To measure this, you figure out the "drip line" of the tree, which can be visualized as the shadow of the tree's crown projected vertically onto the ground.  You then measure its widest dimension.  The second measure is the widest width at any point perpendicular to that longest diameter.  The two perpendicular widths don't have to intersect at the trunk of the tree; sometimes they will, sometimes not.  The Average Crown Spread is the average of the two widths.

    Crown.gif     2nd Crown diameter.gif

         For purposes of comparing trees and deciding a champion, the TFS calculates a "Tree Index" by adding together the circumference (inches), the height (feet), and one quarter of the average crown spread (feet), rounded to the nearest whole number.

    Tree Index = circumference (in) + height (ft) + 1/4 of avg. crown spread (ft)

         So how did our big junipers stack up?  We measured two of the five big trees in the grove.  The tree pictured in my previous blog measured 72 inches in circumference (just shy of 2 ft in diameter), 39 ft tall, and had an average crown spread of 42 ft, giving it a tree index of 72 + 39 + 42/4 = 122.  A second large juniper measured: circumference, 65 inches; height, 41 ft; average crown spread of 38 ft, giving an index of 116.

         The champion Ashe juniper is a bulky monster in New Braunfels which is not much higher (41 ft) nor wider (49 ft) than our trees, but it has a thick truck measuring 139 inches around, giving it an index of 192.

    The State and National Champion Ashe Juniper
    New Braunfels, Texas

    [photo credit unknown; downloaded from the Junipers of the World website]

    You can find information about champion trees all over the country at American Forestry's National Register of Big Trees.

         Can any of these big juniper trees be aged?  Typically, foresters would estimate the age of a living tree by drilling a very narrow core to the center of the tree (the width of a soda straw), taking that core back to the lab and counting the growth rings under a microscope.  For junipers, this traditional method of counting tree rings is very unreliable.  I saw a vivid illustration of this last week when I was examining some other habitat management we are doing.  On the Refuge's Webster tract, we recently put in a deer-proof fence to enclose a rather large area of Golden-cheeked Warbler habitat in a study being conducted in collaboration with the University of Texas.  A number of various sized junipers had to be felled to put the fence in.  That gave me the opportunity to examine the growth rings on some freshly cut juniper trunks.  Take a look at what I found:

    Juniper Growth Rings1_sm.jpg

    Look closely at the (dark) rings on this juniper; a lot of them look "double".  Many of these probably represent separate growth spurts by the tree in the spring (wider rings) and after late summer or fall rains (narrow rings).  Sometimes these might represent growth in a wet year followed by a dry year.  There is no easy way to tell the difference in these two scenarios.  The conclusion:  Ashe junipers don't have a simple correlation of growth rings to annual cycles.

    Juniper Growth Rings2_sm.jpg

    The second major problem with aging such trees is that junipers don't always put on new growth in neat rings evenly distributed around the trunk.  Look carefully at the pattern here, where growth seems to occur irregularly at different places on the tree at different times (years), resulting in a pattern that looks like silt fans at a river delta or wind-blown sand dunes.  This is an intriguing growth strategy and I don't know why it happens.  Once again, imagine trying to core through any one location in this juniper; it would only be by accident that you might pierce through a complete and countable set of growth rings.

    * * * * *
    Below the Line:

         The fact that my original estimates of the height of those big junipers were so far off ("50 ft" versus the reality of ~40 ft) shook my confidence to the core.  Over my years in the field I've had much time to hone my estimation skills--based on comparisons to objectively measured heights, lengths, distances, sizes, etc.--and it is something I have had a quiet confidence in.  Or not-so-quiet if you've ever been on a deer count on a Fall evening with me and I boldly announce the temperature after waving my hand in the air for a few seconds.  My hand is rather well-calibrated to air temps (in degrees Fahrenheit).  My estimates of any given measure might be blurted out in English or metric units; it's not that I convert those easily in my head but it comes from whatever I worked with for standard measurement in a given discipline (e.g. measuring the sizes of plant parts in mm and cm versus estimating the size of a bird in inches or the distance of a hike in miles).

  • Sunday, February 21, 2010 4:00 PM | Anonymous

    Sam Hamilton (1955-2010)
    Director of the U.S Fish & Wildlife Service

    Sam Hamilton was a friend of this Refuge, and a dear friend of ours.
    We will miss him tremendously.

    Links to news coverage of Sam's passing:


  • Saturday, February 13, 2010 7:33 AM | Anonymous
    GBBCBanner.gif     Be sure to watch your feeders and glance around your yard at least once this weekend, then go online and report your findings for the Great Backyard Bird Count, the most casual and relaxing avian monitoring program all year.  This is a mid-winter effort organized by Cornell University’s Laboratory of Ornithology, National Audubon Society, and Bird Studies Canada, and sponsored by Wild Birds Unlimited.  As described on the GBBC website, it is meant to “engage bird watchers of all ages in counting birds to create a real-time snapshot of where the birds are across the continent. Anyone can participate, from beginning bird watchers to experts.”  This effort differs from the recent Christmas Bird Counts in a few important ways:

         (1)  It is local.  As with any birding effort, you can expend any level of energy to accomplish this task, but “backyard” is the operative word, however you define that.  This might literally be your own yard, your favorite city park, a walk on a local nature trail, or a whole day excursion to your favorite wildlife refuge.  That’s your “backyard” for one bird list.
         (2)  Rather than accumulating a grand total of all birds counted all day, the information you report is “the greatest number of individuals of each species seen at any one time”.  For instance, if a flock of 10 waxwings flies over once, then later on you see 30 in a nearby tree, you report 30 waxwings, not the total count.  You might end up reporting the one flock of 10 Turkey Vultures that circled overhead, the one Western Scrub-Jay that came to your feeder, or your high count of 45 Chipping Sparrows all over your yard in mid-morning.
         (3)  It is real-time and online.  When you complete your birding effort, go online and enter your list of birds, then “explore the results” which are coming in from all over the continent.  You can examine species distributions, totals, or the distribution of effort.  You can participate on just one day or more than once, even submitting a new list for each day during this four day event, February 12-15.  You may submit your lists for this weekend until March 1, but the fun of the event is keeping up with it as it is happening.  This may be the perfect boredom reliever for those snow-bound folks on the East Coast!

    BCTI_Lasley_22.jpg                                                          TUTI_Lasley_006.jpg

         Rob Iski and Elizabeth Lesley helped me accumulate a list of 24 bird species for the Refuge on Friday, the first day of the GBBC.  For our purposes, our “backyard” was just the HQ and ops center including the photo blind and Post Oak Creek trail.  Perhaps due to the chilly breeze, birds were not terribly conspicuous this day.  There were no ducks on Post Oak Creek and we didn’t even see a Bewick’s Wren.  I invite you to go to the GBBC results page to find our entire list and further explore what is being seen across the country.
  • Wednesday, February 10, 2010 11:53 PM | Anonymous
         Those of you who have visited and walked around the Refuge HQ are familiar with Post Oak Creek.  Martin Lake_upper.jpgThis is the stream that feeds the pond overlooked by the new photo blind.  It runs down through the pecan grove, nurturing that lone Bald Cypress tree*, and thence under RM 1431, emptying into the Cow Creek arm of Lake Travis.  Some number of you have had the opportunity either to join Jean & Seay Nance on one of their back-country hikes during the Songbird Festival or offered your services to help clean up the Bottom's Up Hunt Camp.  You've seen a hint of what Post Oak Creek is like in the back-country.

         I have taken the occasional opportunity--made up a thin excuse--to get away from the office and really go exploring in this watershed.  Every time I wander the obscure trails and overgrown jeep roads which meander through the broken terrain, I find something interesting, experience something new, or see something that reminds me of the wonder of Mother Nature and the grand forces that shape the landscape.Cascade_port.jpg  When I am not distracted by the birds or butterflies, every such hike offers up a geology lesson, a botany lesson, a hydrology lesson, or a history lesson, if I am just open to the possibilities.

         Although I have enjoyed escaping to this habitat hideaway in the heat of a dry summer, it is in mid-winter--especially in a wet year like this--that the quietude of the landscape can be most appreciated, disturbed only by a noisy stream dashing over limestone ledges and riffles.  No road noise.  No overt sign of modern civilization.  Nothing but ... nature.  The existence of the old roads or the remnants of the hunt camp, and the near-ubiquitous evidence of past cedar cutting can be jarring in this context, but I take comfort that all that has come to a halt.  An overgrown road, to me, means the land is slowly healing.  A fallen tree is evidence of natural processes at work.  Post Oak Creek and the processes of growth, death, decay, and erosion are gradually erasing most evidence of our species' previous influences here.

         At various times and venues, I've shared images Rugged watershed.jpgand told stories of some of my discoveries in this wonderland: energy flow through an ecosystem, a porcupine at close quarters in a crevice, a Varied Thrush glimpsed on one CBC and a Hutton's Vireo "documented" on another, a crystal-dappled ledge, the weeping hillside, and "The Rock", among other features.  I reserve the right to withhold some of my memories of this place.  Each of us should have a few of these, a reservoir of unshared moments in some special place, wherever that might be.

    Pathway.jpg     Creek_Ledge.jpg
    Left:  The pathway to discovery.
    Renewed and refreshed, Post Oak Creek carves through the limestone.
    Above Right:  A rugged watershed, viewed from high on a cliff.

    Madrone.jpg     Moss.jpg
    Left: A happy Madrone in a moist year.
    Right: Mossy pattern on a ledge.

         That said, I really wanted to bring to light what I encountered just today: Four of the biggest, most massive, and most perfectly shaped Ashe Junipers I've ever seen!  I had taken a slightly different path at midday today, easing along a scenic ledge and following an animal trail then an old cedar-chopper road down to a terrace flanking Post Oak Creek, nestled near the confluence of a major side canyon.  It was a spot I hadn't previously visited.  As I moved onto the level terrain, the woodlands grew in stature.  There was an abundance of large Spanish Oaks, some healthy and others broken from various traumas of seasons past.  Second-growth juniper--some of it middle-aged--made up the rest of the canopy and there was an annoying abundance of juniper slash scattered on the ground.  But then I noticed one big straight tree trunk, two feet in diameter at the base, launching into the canopy.  In the deep shade, I thought I perceived the bark of a juniper...but, that big?!  I couldn't even see the top of the tree as it emerged well above the surrounding woods.  It emerged!

    One Giant.jpg
    It's nigh impossible to photograph any single large tree in a forest.
    This was the most exposed of the four giants.

         I glanced around to get oriented--to verify my location--and there, about 30 yards away, stood another massive juniper, and another, and another.  (There may yet be more, but I was quickly engaged in documenting this find and didn't take the time to explore further.)  I had nothing to measure them with so I set my field notebook at the base of one tree and reached up to hang my binoculars for perspective against the trunk of the giant, only to realize that the lowest available branch jutted out nearly 10 feet above my head.  Each of these monsters is probably 50+ ft in height.  Their age?--Who knows!

    Massive trunk.jpg     Binocs_Journal.jpg
    Trying to gain any perspective on the size of one of the giant junipers!
    My field journal is 5" x 8".

         One or another of this set of trees may be the record Ashe Juniper on the Refuge.  Time and more precise forestry measurements will tell.  It was clear from their arrangement--and the thoroughly ravaged juniper woodland around the area, that these particular trees had been conscientiously spared from the saw.  The cedar cutters probably made camp here on this terrace and retained a few big cedars to provide more shade alongside the oaks.  Perhaps these trees were already so big that no useful posts or fence stays could be cut from the trees without a supreme expenditure of time, elbow grease, and fuel.  Perhaps they were heeding "Chuck's Forestry Rule"*.  In any event, for me, discovering a few trees like this is like stumbling upon a lost bison herd or remnant patch of tallgrass prairie.  "Just another day in paradise" ... as the country song says.

    * See "Emergency Tree Protection" in my Dec. 8, 2009, entry.

    * * * * *
    Below The Line:

        I firmly believe that a great deal of landscape history can be learned from the varying shapes and growth patterns of junipers in a given location.  Consider this:  A single-trunked, straight-trunked juniper of necessity germinated and grew up in a dense woodland matrix.  IF, hypothetically, these giant junipers--which may be 100-200 years old or more--grew up in such a woodland, that tells you something about what this little corner of the Texas landscape was like way back when these were just little seedlings!  Other evidence comes, sadly, in the abundance of massive cut juniper stumps which one sees in many locations in the Post Oak Creek watershed.  The happy news is that there are actually a few little protected niches, on the order of a few acres each, where we find intact old-growth woodlands showing no evidence of cutting or fire.  Those are certainly special places.


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