The Inaccessible Rail

Inaccessible Island rail (photo by Brian Gratwicke via Wikimedia Commons)

If you’ve ever gone looking for rails, you know they are usually inaccessible. They live in tall dense marsh grass and won’t come out for anything except the sound of another rail — and then only in the breeding season.

But there is in fact a truly inaccessible rail.  The Inaccessible Island rail (Atlantisia rogersi) is the smallest flightless bird in the world, extremely rare, and vulnerable to extinction.  He lives only on Inaccessible Island.

He made news in October because he cannot fly yet new DNA studies show that his ancestors, related to black rails, did fly more than 2,300 miles from South America over the South Atlantic Ocean to Inaccessible Island.  They arrived 1.5 million years ago.

This was a surprise because the island, which is in the Tristan de Cunha archipelago, is closer to Africa than to South America as shown below. (Click on the map or its caption to explore it on Google Maps.)

Location of Inaccessible Island on the globe (screenshot from Google Maps)

The island is called Inaccessible because it is.  It’s almost impossible to land on the narrow beach — most attempts fail — and the cliffs are so steep that the top is inaccessible.

Panorama of Inaccessible Island (photo from Wikimedia Commons)

The island’s walls dwarf the people exploring the beach, below. 

Inaccessible Island beach, people in the distance (photo by Brian Gratwicke via Wikimedia Commons) 

Fortunately this tour group got lucky. They were able to land and they found the rail. A member of the group, Brian Gratwicke, took these photos.

Read more about the origins of the Inaccessible Island Rail in this article from Researchgate.

(photos by Brian Gratwicke via Wikimedia Commons; map screenshot from Google maps; click on the captions to see the originals)

The Lookout Bird

Dusky-throated antshrike at banding station (photo courtesy of Cameron Rutt)

When you’re vulnerable to predators it pays to stick together and have a good lookout to warn you of danger.

The dusky-throated antshrike (Thamnomanes ardesiacus) doesn’t look important but he’s quick to notice the presence of hawks and falcons and has a distinctive alarm call that wakes up the forest to impending danger.  It turns out that he’s key to the foraging location and cohesion of his mixed species flocks in the Amazon.

Early this year, a study by San Francisco State University temporarily removed dusky-throated antshrikes from their mixed species flocks in Peru. They discovered that within hours the flocks left their semi-open mid-story locations for denser parts of the forest.  Often the flocks without an antshrike completely dissolved.

What does the alarm call sound like?  Is it loud? Does it grab your attention? You bet!  Here’s the sound of a worried dusky-throated antshrike:

His role in the flock works so well that the same mix of species sticks together for generations. As San Francisco State Professor Vance Vredenburg remarked, “You come back to the same habitat after 20 years, and the same flocks are using the same areas of the forest.”

Read more about the study here in Science Daily.

p.s. When the antshrike is not afraid he sings this buzzy, rising song. (audio by Peter Boesman at Xeno Canto #271766)

Dusky-throated antshrike song (Xeno Canto 271766)

(media credits: photo of dusky-throated antshrike by Cameron Rutt, audio alarm call from Macaulay Library, audio song from Xeno Canto; click on the captions to see the originals)

Open Wide!

Wire-tailed swallow bringing food to juvenile (photo from Wikimedia Commons)

This beautiful swallow, native to sub-Saharan Africa and southern and southeast Asia, is very similar to our barn swallow except for its two wire-like tail feathers and its preference to live near water.

The wire-tailed swallow’s (Hirundo smithii) family life is similar, too.  When the fledglings beg for food, the parents deliver it on the wing.

Open wide!

Wire-tailed swallow delivering food to young (photo from Wikimedia Commons)

(photos by Manojiritty on Wikimedia Commons; click on the captions to see the originals)

Birds On The Wire

Birds on wires (photo from Wikimedia Commons)

While you’re out running errands here’s something to do while you wait for the stoplight to change …

Are there birds on a wire near you? What are they doing?

Are they all facing the same way? 

Birds face the wind when they’re perched so the air doesn’t ruffle their feathers and make them uncomfortable and cold. They also land and take off facing the wind so they actually arrived in that direction.

The direction the birds are pointing tells you the direction wind is blowing … except …

if the birds are not facing the same way, the breeze is very light or the air is calm.

(photo from Wikimedia Commons; click on the caption to see the original)

Goshawk in Slow Motion

Earlier this month we watched expert falconer Lloyd Buck fly his peregrine falcons in The World’s Fastest Animal on NOVA.  Here he is in a 6+ minute video putting a northern goshawk through her paces. Watch her perform in slow motion.

You’ll probably notice how similar the northern goshawk is to a peregrine falcon.  The two species aren’t closely related but they need similar skills to survive, so their bodies and actions are similar, too.  The difference is that the goshawk doesn’t dive on prey like a peregrine. The goshawk always chases.

p.s. The complete 53-minute video of PBS NOVA’s program on peregrine falcons — The World’s Fastest Animal — is viewable online at

(video from BBC Earth Unplugged on YouTube)

Tiny Opals

Hackberry fruits (photo by Paul Wray, Iowa State University,

This month I read Lab Girl by Hope Jahren and learned that she made an amazing discovery in 1998 during research for her doctoral dissertation:  Inside common hackberry fruit is a small hard pit with a lattice made of opal.

Hackberry fruits, pictured at top, are drupes similar to cherries and peaches with fleshy fruit surrounding a central pit.  The fruit is thin and the pits are large so we rarely eat hackberries but birds love them.

The pits in cherries and peaches are made of wood (or something like it) but hackberry pits are made of stone: calcium carbonate inside a lattice framework. When Hope Jahren used Xray diffraction on the crushed lattice material its composition came up “opal.” 

When I found this out I searched for the pits under hackberry trees in Schenley Park. At this time of year the fleshy purple fruit is gone, only the white pits remain.  Here’s what I found, one whole, one opened. The exterior is a network of tiny raised lines. 

Opal is in these hackberry pits (photo by Kate St. John)

The pits don’t look like opal and probably never will.  You’d have to use acid to remove the calcium carbonate (the white stuff of seashells) and then examine the remaining latticework under a microscope.  There’s a tiny bit of opal in there.

And so I wonder: How does a tree put opal in its drupes?  I don’t know, but here are the raw materials:

[The rock] Opal is formed from a solution of silicon dioxide and water. As water runs down through the earth, it picks up silica from sandstone, and carries this silica-rich solution into cracks and voids, caused by natural faults or decomposing fossils. As the water evaporates, it leaves behind a silica deposit. This cycle repeats over very long periods of time, and eventually opal is formed. 

From Opals Down Under

Trees take up water that contains dissolved minerals including the building blocks of opal.

Miraculously, the hackberry tree pulls out what it needs and makes an opal latticework inside its drupes.

Learn how to identify hackberry trees in winter at Winter Trees; Hackberry.  Then search the leaf litter for tiny opals.

For further reading see : Hackberry: A Gem of a Weed

(photo credits: hackberry fruits by Paul Wray, Iowa State University,, hackberry pits by Kate St. John)

Starting A Family In November

Barn swallow (photo from Wikimedia Commons)

Barn swallows (Hirundo rustica) are found on every continent except Antarctica, breeding in the northern hemisphere and wintering in the southern hemisphere with one notable exception: a small population breeds in Argentina. 

This behavior was unknown until 1980 when scientists confirmed that northern-born barn swallows had decided to nest during South America’s spring.  They’ve even shortened their return migration, traveling only as far as the equator during South America’s winter.

Scientists speculate that the birds are breeding in Argentina because we changed the landscape to their liking.  99% of barn swallows prefer to nest on man-made structures including farm buildings, bridges and boathouses.  They found what they like near Buenos Aires.

Barn swallows and nest on man-made structure (photo from Wikimedia Commons)

Because these swallows have flipped their north-south patterns a Cornell University study reports that this could be the first step toward a new species, similar to terns and skuas that have distinct northern and southern species (example: great skua and south polar skua).  For now, though, the Argentinian barn swallows still recruit northern-born swallows to join them.

Fledgling barn swallows beg for a food delivery from their parent (photo from Wikimedia Commons)

While we’re cold up here in North America, some barn swallows are starting families in November.

Read more about the Argentinian barn swallows here at Cornell CALS.

(photos from Wikimedia Commons; click on the captions to see the originals)

The Trees Are Still Standing

Camp Fire damage in a Paradise, California, neighborhood, Nov. 17, 2018 (photo by Senior Airman Crystal Housman, California Army National Guard)

In all the smoke-filled photos of the Camp Fire devastation in Paradise, California one thing stands out to me:  The buildings are gone but the trees are still standing.

The town of Paradise, California (population 26,000) was destroyed on 8 November 2018 by the Camp Fire, the deadliest and most destructive fire in California history.  As soon as it ignited at 6:30am, the fire raced westward on 50-70 mph winds. By 8am it reached the Paradise Town Limit six miles away. Seven towns were forced to evacuate but not everyone made it out. As of 26 November, 88 are confirmed dead, 203 are still missing and tens of thousands are left homeless.

But the trees survived.  You can see them in all the photos and videos including these taken on 17 Nov by the California National Guard as they searched the rubble and marked the damage. 

Soldiers from the California Army National Guard’s 649th Engineer Company, Chico, conduct search and debris clearing operations, Nov. 17, 2018, in Paradise, CA (photo by Senior Airman Crystal Housman)

Because the trees are still standing, the damage assessment has to be done by hand. This Washington Post article shows how the satellites can’t see through standing trees. 

So why are the trees OK in this incinerated landscape? I’m sure it has to do with moisture.

U.S. Army Sgt. Rodrigo Estrada of the California Army National Guard’s 649th Engineer Company, Chico, leads a team conducting search and debris clearing operations, Nov. 17, 2018, in Paradise, CA (photo by Senior Airman Crystal Housman)

Living trees contain more moisture than the dry wood in buildings. When blowing embers hit houses, they catch fire immediately. The trees’ moisture resisted. The fire moved on.

This video by Mike West shows how quickly fire consumes dry wood compared to living trees.

The scene is spooky now. Nearly everything is gone but the trees are still standing.

Soldiers from the California Army National Guard’s 649th Engineer Company, Chico, conduct search and debris clearing operations, Nov. 17, 2018, in Paradise, CA (photo by Senior Airman Crystal Housman)

p.s.  Some trees are damaged and will fall sooner or later.  Here’s an NPR story about trees in the fire zone.

p.p.s. See the damage extent on Cal-Fire’s Camp Fire Structure Status map.  See satellite images here in the Washington Post

(photos by Chico California National Guard, YouTube video by Mike West)

They Use Roads To Fly Home

Racing pigeon and pigeons racing (photos from Wikimedia Commons)

Humans build expressways but we aren’t the only ones who use them.  Back in 2004 scientists tested a theory that racing pigeon owners suspected was true:  Pigeons will follow major roads to guide their flight home.  In fact, the birds will go out of their way to turn at intersections.

In a study conducted in Italy, researchers released racing pigeons fitted with GPS backpacks from sites 20 to 80km from home (12.5 to 50 miles).  In over 200 flights, the data showed that experienced pigeons preferred to follow roads and rail lines in the early and middle parts of their trips.  As they got close to home they left the road grid and made a beeline for the loft.

On the first trip from each site pigeons didn’t use the grid, but the more they made the same trip the more they used big roads.

Why do they do this?  Scientists suspect that easier navigation above major roads makes up for taking slightly longer routes. The birds don’t have to think about where they’re going and can focus on flying fast and watching for predators.

That’s why I take expressways in my home town, even when they’re clogged at rush hour.  I know the back roads but I’d rather not think about navigating.

Read more about the 2004 study in Science Daily.

(photos from Wikimedia Commons; click on the caption links to see the originals)

Cranberries Float

Cranberry on Mt. Davis, 14 Oct 2018 (photo by Kate St. John)

In October the Botanical Society of Western Pennsylvania went on a field trip to Christner Bog on Mt. Davis, the highest mountain (actually a plateau) in Pennsylvania.  We were admonished to bring waterproof boots so I wore my best muck boots. They’re ankle high and they were not enough.

It rained so much this fall that the bog was over-full.  I learned that day that plateau bogs are surrounded by a moat of deeper water. (Knee-high boots required!)  It was a huge challenge to tiptoe on submerged branches and lumps to cross the moat.

On the other side of the moat, the water was still too deep for my boots so I stood on a hummock while everyone else explored the center of the bog.

Botanical Society of Western PA outing to Christner Bog on Mt. Davis, Oct 2018 (photo by Kate St. John)

They found lots of cool plants among the sphagnum moss.  I looked down and found wild cranberries (Vaccinium oxycoccos).

Wild cranberries among the sphagnum moss, Mt. Davis, 14 Oct 2018 (photo by Kate St. John)

So I picked one, shown at top.

I wish I’d opened the berry to see the air chambers that hold its tiny seeds.

Cranberries inside and out (photo from Wikimedia Commons)

Instead I dropped the berry in the moat on my way out, hoping an animal would eat it later.

I’d forgotten that cranberries float.

(photos by Kate St. John)