Early this month it was scary to read Chuck Tague’s account of a brush fire that came within two miles of his Ormond Beach home.

While the fired burned in Florida I was in another fire-prone place, San Diego, listening to a speech by Dr. John Fitzpatrick of the Cornell Lab of Ornithology in which he touched on how important fire is for scrub habitats and for the survival of the Florida scrub-jay in particular.

To most of us wildfire is rare but it’s a natural cycle in scrub communities where plants, animals, and birds rely on its regular occurrence.   “Regular” is important.  If fire happens too often or too infrequently that’s bad too.

It has taken a while to learn this.  Dr. Fitzpatrick described how they studied fire and birds at Archbold Station in Highlands County, Florida.  For two decades Archbold suppressed fires and watched the scrub-jay population surge then dangerously decline.  After 20 years scientists burned small tracts and watched the scrub-jays surge again.  They learned that the Florida scrub-jay’s optimal habitat is at 5-15 years after a fire.  At 15 years the scrub gets too tall, the jay’s predators increase and the birds decline.

Fire is necessary.  The trick in populated areas is to manage it so it happens only when and where it’s needed.

In San Diego the local government conducts brush management programs to protect homes and businesses.  According to San Diego Audubon, these programs sometimes make matters worse.  If workers clear away native chaparral, it not only destroys endangered bird habitat but results in fire-prone grassy weeds that burn more easily. Proper management of native habitat actually lowers the risk of explosive fire.

So though we fear it, fire is important.  Without it we wouldn’t have Florida scrub-jays, California gnatcatchers and coastal cactus wrens, to name a few.

(photo of a helicopter dropping water on a California wildfire, by FEMA via Wikimedia Commons. Click on the image to see the original.)

5 March 2013

Travel is very educational.  Not only are there different birds in San Diego but the threats those birds face are different from what I’m used to in Pittsburgh.  One issue particularly grabbed my attention because we never have to deal with it at home.

Where I come from it’s hard to imagine the wall that defines the southern edge of San Diego County and most of the U.S. border from here through Texas.  Like the Berlin Wall it’s patrolled by armed guards, edged by cleared land for easy enforcement, and in places triple-fenced.

The border has been patrolled for a long time but the Real ID Act of 2005 mandated the border wall and exempted its construction from every environmental law including the Endangered Species Act, the Migratory Bird Treaty Act, the Clean Water Act, the Clean Air Act, and the National Environmental Policy Act.  Exemptions like this bring to mind mountaintop removal in West Virginia.

During design of the Triple Fence, San Diego Audubon and other groups tried to prevent the worst environmental damage but it was impossible to stop the juggernaut.  Now that the wall is up, they’re working with California State Parks and the Tijuana National Estuarine Research Reserve to monitor the wall’s effect on sedimentation, erosion, and invasive plants.

There are lots of problems to monitor.  Here are just two examples.

The fence through Yogurt Canyon, shown above, disrupts the natural drainage into the Tijuana Estuary to the north.  This affects everything that depends on the water, including birds.

At Border Field State Park, shown below, the wall’s construction leveled Litchy Mesa and filled Smugglers Gulch.  There used to be a single fence.  Now there’s a massive valley-fill and all the issues that come with it.

Ironically, the wall has an unintended consequence.  In the old days workers used to migrate back and forth like the birds — north for planting and harvesting, south to their homes in the winter.

In his 2001 book, Crossing Over, Rubén Martínez described how the patrols even then were ending the return migration.  It’s now so dangerous at the wall that those who make it to the U.S. rarely leave — because they can’t.

I’m sure that’s not the result the wall’s proponents had in mind.

Read more about the border fence and how it affects the land and people of Tijuana and San Diego in Jill Marie Holslin’s blog At The Edges.

(photos used by permission of Jill Marie Holslin from her blog, At the Edges. Click on each image for more information.)

Romancing the Wind from Robert Holbrook on Vimeo.

My love of birds has me fascinated with almost anything that flies.  Perhaps this is true for you too.

Last month my sister-in-law sent me a link to this 2004 video called Romancing The Wind.  Produced by Robert Holbrook, it shows professional kite flyer Ray Bethell flying three kites simultaneously in an aerial ballet.  Music from Leo Delibes’ The Flower Duet complements the kites.

Ray Bethell is an amazing man.  Over 80 years old, he’s a Multiple Kite World Champion from Vancouver, Canada who holds world records in endurance and number of simultaneous kites flown.  Here you see him flying three kites at Vanier Park, holding one in each hand with a third tied to his belt.  He’s used this same technique to fly 39 kites at the same time!  Read more on his website here.

Like the falcons, Ray Bethell’s kites court in the wind.

p.s. The kite model Ray is using has a falcon name:  Kestrel.

(video of Ray Bethell by Robert Holbrook on Vimeo)

I rarely spend time near sand dunes so I was amazed to learn that sand can sing.  In fact there are 35 places around the world where the dunes sing a low frequency hum in the bottom half of a cello’s range.

The droning happens naturally when the wind causes a sand avalanche.  People can force the song by pushing sand downhill.  The songs are well known but people have always wondered how and why they happen.

Some of the “how” is already known.

Singing dunes are crescent-shaped barchans with their backs to the wind and their horns pointing downwind.  The slipface is inside the crescent (downwind) with its surface at the angle of repose and a stationary layer beneath.

Experiments have shown the importance of the grains themselves.  If they’re spherical,  0.1 to 0.5 mm in diameter, and contain silica, they will sing in the lab when they slide down an incline.

This year physicists from Paris Diderot University discovered that grain size determines the tune.  They studied two dunes:  one in Morocco, one in Oman.   The Moroccan dune has grains 150-170 microns and emits a 105 hz sound (for musicians that’s near G-sharp two octaves below middle C).    The Omani dune has a variable grain size from 150 to 310 microns and its sound varies, too — from 90-150 hz (F-sharp to D).

Researchers took the Omani sand back to the lab and sifted it down to a nearly uniform size — 200 to 250 microns — and sent it down an incline.  Voilà.  The sand made a sound of 90 hz, close to the song of the Moroccan dune.  (Click here for more information about the study.)

What are the songs like?  In this video, filmed in Morocco, a man shows how he learned to make the sand sing.  Turn up your speakers and you’ll be able to hear a variety of sounds as he puts the sand through its paces.  The video is in French with subtitles, some of which are surprisingly translated as in the first sentence that says “Beware” when it means the less dangerous-sounding “Be aware.”

Thanks to science we’ve learned how the sand sings, but we still don’t know why.

(video from YouTube)