Archive for November, 2011

Nov 30 2011

Winter Trees: White Ash


Here’s a tree that will soon disappear from western Pennsylvania, a victim of the emerald ash borer.

White ash (Fraxinus americana) is easily identified by its twig with the chocolate-brown bud.  The twig is stout, the leaf buds are opposite each other, the leaf scar is a horseshoe shape under each leaf bud, and all the buds are chocolate brown.   (Click here for definitions of twig anatomy.)

It’s easy to find these buds in our area.  There are many white ash seedlings now because the trees have put out a lot of seed while they’re under attack.

Opposite leaf buds are a good marker for the ash because most trees have alternate leaves.  The main species with opposites are maples, ashes, buckeyes and dogwoods.  I learned to remember opposite leaves with the acronym MAB DOG (Maple, Ash, Buckeye and Dogwood).

White ash bark is distinctive too.  Its deeply ridged and the ridges join to form long diamond shapes as shown below.

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Unfortunately, larvae of the emerald ash borer kill the tree by tunneling under the bark and damaging the phloem and xylum.  Often this causes the ridges to slowly separate from the bark.  Woodpeckers hear the larvae (amazing!) and chip away at the ridges to get at the bugs.  The result is that a dying tree has pale patches where the ridges fell off.  Infected trees try to survive by sending out sprouts near the ground.  You can see both effects on the trunk below.

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If you examine the chipped bark closely you may find the D-shaped exit hole of the emerald ash borer.  (Thanks to Dianne Machesney for this photo.).

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Learn the white ash now.  Sadly, it won’t be with us much longer.

(photos by Kate St. John, except for the one noted by Dianne Machesney)

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Nov 29 2011

Quiz: What Plant?

Published by under Plants,Quiz

I discussed epiphytes a couple of days ago because I wanted to use this beautiful photo as a quiz. 

Though this looks like an artistic squiggle it’s actually a close-up of a plant. 

Here are some hints to its identity:

  • It’s an epiphyte.
  • It’s native to the southeastern U.S. where the climate is warm with high humidity.
  • It has tiny inconspicuous flowers.  (As many times as I’ve seen this plant I’ve never noticed any flowers.)
  • Its leaves are alternate, thin, heavily scaled and curved.  These are its leaves. 
  • The leaves appear to form long chains.
  • Big hint: It’s commonly found hanging from southern live oaks and bald cypress trees.

Can you guess what it is?

Leave a comment with your answer.

(photo by Ernest V. More in the public domain on Wikimedia Commons)

11 responses so far

Nov 28 2011

Harvestmen

Published by under Insects, Fish, Frogs

Last weekend in southern Virginia I saw a troop of six daddy longlegs exploring the edge of a hiking trail. What were they doing?

I searched the Internet for information and though I didn’t find that answer I learned some fascinating things — and their real name.

I call them daddy longlegs but their real name is harvestmen. They’re very ancient and diverse bugs with more than 6,400 species on earth that date back to the Devonian era 400 million years ago.  Compared to humans who reached our present form 200,000 years ago, this bug goes way back!

Harvestmen are arachnids but they’re not spiders (Araneae), they’re Opiliones.

Unlike spiders their bodies look like a single oval because the segments are joined broadly.  They can’t make silk, they have no venom, no fangs and are completely harmless to people.

Harvestmen can eat solid food (spiders have to liquefy their food and suck it in) and they’re omnivorous, willing to ambush prey or scavenge the dead.  They’ll even eat bird dung.

The bird connection works both ways.  Birds eat daddy longlegs but the bugs have a decoy system.  A harvestman can lose a leg and it’ll continue to twitch because of  a “pacemaker” at the end of the first segment (the pacemaker is useful in controlling such a long leg).  The twitching distracts the predator while the other seven legs carry the bug to safety.  At least one of the bugs I watched last weekend was missing a leg.

And what were so many of them doing together?  Apparently some species of harvestmen are gregarious and will congregate in groups of 200 to 70,000 individuals.

Maybe the six of them were having a small party.

(photo of Phalangium opilio by Mehran Moghtadai from Wikimedia Commons.  Click on the photo to see the original.)

p.s. In this blog I’m using the word “bug” loosely.  True bugs are insects (six legs) with a chitinous (hardened) wing cover. Harvestmen are not really bugs; stink bugs are.

6 responses so far

Nov 27 2011

Epiphyte

Published by under Plants


“Upon plant”

That’s what epiphyte means in Greek (epi=upon, phyte=plant) and that’s what an epiphyte is:  a plant upon a plant.

I never thought about this word until I saw some interesting epiphytes in the forest while visiting my family in southeastern Virginia.

True epiphytes are sometimes called air plants because they collect their water and nutrients from rainfall, mist, dust and the surrounding air.  Though they’re held aloft by a host plant they aren’t parasites and never directly harm their host.

As proof, here’s a photo of epiphytes growing on telephone wires in Bolivia.

I’ve seen this in Florida too.  I’m sure it annoys the phone company.

We normally think of epiphytes as tropical plants like the red orchid pictured above, but all kinds of plants-upon-plants grow wherever there’s enough humidity or rainfall and clean air.

Mosses, lichens and ferns are the epiphytes I usually see in Pennsylvania.  They seem almost boring because I’m so used to them.

Do you have interesting epiphytes where you live?

(photos via Wikimedia Commons.  Click on each photo to see the originals)

2 responses so far

Nov 26 2011

Talk About Speed

Published by under Water and Shore

Red-breasted mergansers have arrived at Lake Erie. 

These are cold weather ducks whose breeding range is holarctic.  In North America they winter at the Atlantic, Pacific and Gulf coasts and on the Great Lakes.  This week at Lake Erie Jerry McWilliams has reported large numbers of them, more than 1,500 at a time. 

Like many diving ducks, red-breasted mergansers’ legs are positioned so far back on their bodies that it’s awkward for them to walk.  They don’t spend much time on land. 

On the other hand, they excel in water and in the air. Their claim to fame is that they’re fastest ducks on earth.  Red-breasted mergansers have been clocked at 80 miles per hour in level flight (some say 100 mph). 

How do they do this?  Scientists say their wings are shaped for high speed and they’re able to do a special maneuver with their feathers.  During the upstroke red-breasted mergansers reverse the tips of their primary feathers to provide greater propulsion, especially during takeoff. 

They aren’t the fastest bird on earth.  Peregrine falcons are.  Peregrines can dive at 200 miles per hour and they’re so famous for eating ducks that their nickname is the “duck hawk.”   

So how would a peregrine match up against a red-breasted merganser if he had to chase it in level flight?   He’d lose.  The peregrine’s maximum level flight speed is 70 mph.  

This is one duck that could escape a peregrine falcon — if the peregrine’s on his level. 

Talk about speed! 

(photo by Steve Gosser)

One response so far

Nov 25 2011

Just a Mild Fascination

Published by under Mammals,Plants

Jonathan Nadle is fascinated by porcelain berry.  He wondered if his cat would be too.

I think it’s safe to say the cat did not catch Jonathan’s enthusiasm. 

Click on the photo of Larry Cat to see the very mild reaction of one imported species (Felis catus) examining another (Ampelopsis brevipedunculata).

(photos by Jonathan Nadle)

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Nov 24 2011

Zoology of Desire


The most fascinating principle I learned from Michael Pollan’s Botany of Desire is that the plants humans want (desire) are the ones that thrive.

Thanksgiving is a good reminder that this principle applies to turkeys, too.

Humans have probably hunted wild turkeys since Native Americans first arrived on this continent.  The pre-Columbian Mexicans domesticated wild turkeys between 800BC and 200BC.

When Spanish conquistadors arrived 2,000 years later, in the early 1500s, they agreed that domestic turkeys were quite tasty and shipped some back home.  Turkey became such a popular food in Europe that when the English settlers came to North America they brought domestic turkeys with them.

Wild turkeys were at their peak.  Then things went downhill.  Over the next 200 years habitat loss and unregulated hunting decimated the wild turkey population until there were only a few thousand left in Pennsylvania.

They could have gone extinct in eastern North America.  Our desire brought them back.

In the late 1800’s Pennsylvania realized that hunting had to be regulated.  The newly formed Pennsylvania Game Commission banned turkey hunting and rebuilt the population by stocking birds from Mexico.  Then in 1929 they began a propagation program that raised wild turkeys for release into the wild.

This combination worked so well that today Pennsylvania’s wild turkeys have a thriving population of over 360,000 birds.

Wild turkeys are smart about predators, as we learned on PBS’s My Life as a Turkey. They’re wary where hunted but relatively easy to see in Pittsburgh’s suburbs and city parks.

So on Thanksgiving Day it’s interesting to reflect that most of us eat domestic turkeys.  Our desire to eat them nearly extirpated wild turkeys and that same desire brought them back.

Turkeys could be a chapter in the zoology of desire.

(photo by Cris Hamilton)

p.s. If you missed My Life as a Turkey on PBS, you can watch the full episode online here.

7 responses so far

Nov 23 2011

Winter Trees: Hackberry

Today is the first entry in this winter’s Wednesday tree series.

Though I mentioned we would identify trees by their twigs I can’t resist starting the series with a tree that’s really easy to identify by its bark.

This is the Northern Hackberry (Celtis occidentalis), a member of the Hemp family.  It produces small berries that ripen in autumn.  Some berries fall to the ground, others persist on the tree into the winter and provide a good food source for birds.

For me the easiest way to identify young hackberry trees is by their bark.  (Bark is at eye level!)

Hackberry bark looks as if someone glued lumpy pie-crust ridges onto the originally smooth gray surface.  You can see these odd ridges in the photo above.

 

A second very distinctive trait is the witch’s broom, easy to see when the leaves are off the trees.  Not all hackberries have these bundles of malformed twigs but when you see them in combination with the lumpy bark you can be sure you’ve found a hackberry.

Here’s a close-up of a witch’s broom.  Not only do the twigs clump at one spot but there are woody lumps at their base.

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As the trees mature the pie-crust lumps grow farther apart and sometimes look as if they’ll peel off the trunk.

Hackberries are easy to find in Schenley Park, especially near the Greenfield Bridge.

(three photos by Kate St. John.  Photo labeled UGA5188076 is by Whitney Cranshaw, Colorado State University from Bugwood.org )

4 responses so far

Nov 22 2011

Lots o’ Robins

Published by under Migration,Songbirds

American robins are amazingly hardy birds.  They now breed north of the Arctic Circle in Alaska and are found year round in most of the U.S.

Since robins eat fruit and forage on the ground for invertebrates they can put up with chilly weather, but when snow covers their food they move south in large numbers.

Visiting robins are already here.  Yesterday I saw some very pale birds among a flock eating porcelain berries.  I’ve read that the pale ones are from the West.  I wonder where…

Right now the robin flock is still building in Pittsburgh and will peak around Christmas before January’s snow.  If you’re near their roost at dusk or dawn you’ll see them swirling, thousands upon thousands of birds.

This video shows what it’s like, filmed near Daytona Beach, Florida in December 2008.

Enjoy our visiting robins now.  They’ll be heading south to visit Chuck Tague (near Daytona) in about six weeks.

Lots of robins!

(video posted by jayc28 on YouTube)

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Nov 21 2011

The Observer Effect

Published by under Mammals


There’s a principle in physics called the observer effect that states the observer cannot help but affect the outcome of the experiment. 

I think this applies to mice.

After your advice last week I put a peanut-butter-laden snap trap inside the ductwork at the only spot that’s flat.  Though it was rather far from the mouse’s last known location, he should have smelled it.  It was upwind.  Two days passed.  No mouse.

Saturday morning I was contemplating a change to my bait strategy when Emmalina took a deep interest in the kitchen heat vent again.  I lifted the vent cover and the unseen mouse immediately scrabbled deeper into the ductwork.  Aha!   He was near the top.

I wanted to use a snap trap but there’s no way to keep a healthy cat out of the kitchen.  The entry has no door to close and there’s a window pass-through to the dining room. 

So I erected an elaborate contraption which wouldn’t have been necessary if I didn’t have a cat.  I took off the vent cover, put a snap trap near the opening and covered all of it with a cardboard box.  I taped the box to the floor, not because I feared the mouse would escape, but because I knew Emmalina would overturn the box if I didn’t nail it down. 

We waited.

Sunday morning Emmalina was sleeping on my lap when we heard the mouse climbing up the vent.  I froze to wait.  She jumped into action.

The mouse kept making noise until Emmy danced on top of the box and tried to dig everything away from the wall.  He scrabbled back into the vent and now, 24 hours later, we have not heard him since. 

This morning I again peeled the blue painter’s tape from the box seam and checked inside.  Nothing.

Am I too impatient or is it time for a new strategy that’s less prone to error?

I don’t know how to compensate for the observer effect.

(photos by Kate St. John)

18 responses so far

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