Archive for August, 2011

Aug 22 2011

The Water Table

Published by under Weather & Sky


Last Friday afternoon our basement floor was briefly lower than the water table. 

At 3:45pm Friday a violent thunderstorm moved so slowly over Pittsburgh that it dropped as much as 2″ of rain within half an hour.  Flash floods filled the streets, stranded motorists, and drowned four people on Washington Boulevard (so tragic!).

But I didn’t know that at the time.  I was at work, watching a huge muddy lake form over Central Catholic’s parking lot and football field.  Definitely not a good sign.  I decided to stay at my desk.

By 5:00pm the lake was gone so I went home.  On the way there I thought about the basement. 

Our 104-year-old house is built into the side of a hill with the back of the basement below ground and the front above.  Though it’s not prone to flooding, very heavy rain (Hurricane Ivan) leaks in from above by following the electric and air conditioning chaseways.  When I got home I took a look.

It’s a good thing we’ve never “finished” the basement.  Its concrete floor was poured after the house was built and is uneven.  A minor flood had gone down the drain but I was able to mop up a gallon from the low spots.  Then I set up fans to dry the floor.

On Saturday morning I examined my handiwork.  The floor was dry but the base of the back wall was still damp.  Aha!  Some of the water was behind that wall.  How did I not notice this before?

I wasn’t paying attention.  The water table is the top of the zone where the subsurface is saturated with groundwater.  It rises and falls as groundwater is added — or not added — by rainfall and snow melt.  When it rises above the low spots on the surface, streams and rivers form.  On Friday afternoon before I got home a little stream was in my basement.

I’m glad I wasn’t there when it was happening.  I’m glad I wasn’t on the road either. 

It’s not good to be in the zone of intermittent saturation.

(image from Wikimedia Commons. Click on the image to see the original.)

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Aug 21 2011

The “Famous” Moth

Published by under Insects, Fish, Frogs


Earlier this month Tim Vechter found this Polyphemus moth on a tree trunk in the city’s Shadyside neighborhood. 

Finding such a huge moth — with a wingspan of 6″ — is always amazing but even more so in the city where we don’t expect to see wildlife.

It probably likes Shadyside’s habitat.  Polyphemus don’t eat when they’re moths but as caterpillars they feed on a wide variety of deciduous trees including oak, maple, hickory and beech.  Shadyside’s tree-lined streets provide a nice selection of mature host plants.

When Pittsburgh was a smoky city the moths probably weren’t here but all it took was one female to make the leap back to town.  The males’ bushy antennae can detect female pheromones from miles away and they’ll fly that far to mate with them.

Polyphemus moths are noticeable because of their huge size and the purplish eyespots on their hind wings.  Those two traits gave them their name. 

Polyphemus was the one-eyed giant who ate six of Odysseus’ men.  He was well known among the Cyclops.  His name means “famous.” 

(photo by Tim Vechter)

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Aug 20 2011

Eating Mayapples

Published by under Plants


Eating wild plants can be a roll of the dice.

Some are completely edible.  Others have both poisonous and edible parts.  Still others are poisonous most of the year with a brief window when you can safely eat them.

Mayapple is one of the the tricky ones.  The entire plant is poisonous except for the ripe fruit. 

Ripeness is key — don’t eat it too soon!  — but good luck finding one.  Wild animals usually consume them before we find the fruit.

Last weekend, Dianne and Bob Machesney found a ripe mayapple and decided to taste it.  Dianne sent these photos and said: 

“We found a mayapple that the chipmunks missed and it was ripe.  I know that they are edible when ripe but never get to taste one before the critters.  Bob cut this one in half and we shared it.  It was juicy and fresh tasting, like a lemony cucumber and the good news, we are both still alive.”

The roots are another story.  Dianne told me “legend has it that any female who digs up a mayapple will get pregnant” but I wonder how this legend came about.  Native Americans used small doses of the powdered roots as a purgative/laxative but the dosage had to be small.  Too much meant death.  

As I said… a roll of the dice.

(photos by Dianne Machesney)

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Aug 19 2011

Peregrine Dive

Published by under Peregrines



Lynne Hyatt sent me a link to this video of a sky-diving peregrine from the BBC’s Inside the Perfect Predator.

I think you’ll enjoy it.

p.s. Since I work for television I’ll admit I spent some time thinking about how they got the video footage and how they edited it. Why are buildings and street grids tiny in some shots (was the bird at 20,00 feet?) and normal in others?  Did they use animation?

(video from YouTube and the BBC Video)

4 responses so far

Aug 18 2011

Born in a Compost Heap

Published by under Bird Behavior

Australian brush turkeys don’t incubate their eggs and they don’t feed or protect their young.  The species survives because their eggs are incubated in compost heaps and their chicks are born super-precocial.

The compost heaps, called incubator mounds, are huge — about 10 feet wide and 4.5 feet deep.  Brush turkeys construct them by scraping a pit and filling it with a huge pile of decaying leaf litter covered over with loose soil.

Several females lay eggs in the same mound but after laying the females leave them alone.

Because temperature is key to incubation the males tend the mounds, testing the temperature by inserting their beaks and adding or removing leaf litter to maintain the correct 91.40 to 950F temperature.

Parental care ends there.

Unlike American wild turkeys (no relation), brush turkeys don’t protect their young.  The chicks hatch inside the mound and dig their way out.  When they emerge they’re able to walk, feed themselves and even fly!  They’re not just precocial, they’re super-precocial.  They fly better than the adults.

Watch this video from Science Friday (5 Nov 2010) to see how well a baby brush turkey can fend for himself.

(video from this article on  Science Friday)

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Aug 17 2011

Fibonacci

Published by under Musings & News,Plants


This spiral is demanding that I blog about Fibonacci.  He was in the news last Friday because there’s a new book about him, and two weeks ago Chuck Tague said that the Fibonacci sequence describes spirals like these.

So I wondered… What are Fibonacci numbers?  And what do they have to do with spirals?

Fibonacci was a great Italian mathematician of the Middle Ages.  In 1202 he published Liber Abaci (Book of Calculation) in which he introduced the Hindu-Arabic numeral system to Europe and taught them calculations using digits 0-9 with place value.  Until that time, Europe used Roman numerals for commercial bookkeeping.  Imagine how hard that was!  CCXLVIII + MDCCCLXXIX = ?

In Liber Abaci Fibonacci discussed mathematical problems and calculations.  One of his “story problems” was about rabbits:

  • Start with 1 male and 1 female rabbit in a field
  • They produce 1 male and 1 female rabbit every month from their second month of age onward.
  •  The young rabbits mature, pair up, and mate producing 1 male and 1 female per month from the second month of age onward.
  • The rabbits never die. 

How many pairs of rabbits will be in the field at the end of one year?

The answer is a mathematical pattern that describes how many pairs of rabbits exist at the end of each month.   Start with 0 and 1 and put them in a row.  Add them together to produce the next number in the sequence.  Put this number at the end of the row and add those last two numbers to get the next one.  Keep doing this forever.  

       0,1
0+1=1  0,1,1
1+1=2  0,1,1,2
1+2=3  0,1,1,2,3
2+3=5  0,1,1,2,3,5
3+5=8  0,1,1,2,3,5,8

Thus the Fibonacci sequence:  0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 610,…

How do Fibonacci numbers describe spirals? 

Imagine drawing squares whose edge lengths are the units in the Fibonacci sequence.  Each time you draw a new square, make it touch the ones you drew before.  Because each number in the sequence is larger, the new squares touch the old ones on their long edge.  Eventually you’ll notice that you are drawing squares in a spiral.  …Yes, this is hard to imagine.  Click here for an animation that shows how this works. 

How does this apply in nature?  Amazingly, the number of parts on a plant, the branching arrangements and the spirals of seed heads often follow the Fibonacci sequence.  Here are some real life examples (scroll down on the website).

I hope I haven’t lost you by now!  

I’ve only grazed the surface of Fibonacci in nature so if you’d like to learn more see this educational math website from Surry, UK that has good, simple examples and animations.

I really like numbers.  I get excited by these things.

(photo of a maypops tendril by Chuck Tague)

5 responses so far

Aug 16 2011

Coming Soon to a Tree Near You


If you haven’t seen these webs in the trees, you will soon.

These are the communal webs of fall webworm caterpillars (Hyphantria cunea).

Their mother laid a mass of eggs on a deciduous tree, preferably a cherry, apple, ash or willow.  A week later the eggs hatched into tiny caterpillars and they began to build their web, mostly at night.

The caterpillars live inside the web, molting as they grow, and extending it to surround the leaves they’re eating.  The web can become as much as three feet long but it’s very different from the tent webs we see in the spring.

Tent caterpillars build in the forks of branches and come out of their nest to eat.  Fall webworms build at the tips of branches and stay inside to eat, only emerging on very hot days (too hot to stay inside!) or when they’ve reached their final instar and are ready to pupate.

Hyphantria cunea overwinter in the pupal stage under loose bark or debris on the ground.  When they emerge in the spring they look like this with a 2″ wingspan:

Unless you have an infested orchard, fall webworms aren’t that bad for trees and they’re quite good for birds.

The caterpillars don’t permanently harm the trees because they’re eating the leaves at the end of the growing season when the trees would drop them anyway.

And they’re an important food source for birds.  Migrating warblers see the webs as huge advertisements:  “Come eat!  Good protein inside!”

When you see fall webworms in the trees, think “happy warblers.”

(Web photo by G. Keith Douce, University of Georgia, Bugwood.org.  Moth photo from Wikimedia Commons.  Click on each photo to see its original.)

7 responses so far

Aug 15 2011

Shy?

Published by under Water and Shore


Here’s a bird you don’t see every day — even if you live near a saltmarsh.

This is a family of clapper rails (Rallus longirostris), a chicken-sized bird who lives on the coasts of North and South America, ranging from California to Ecuador and Cape Cod to Brazil.  (There’s also a small population along the lower Colorado River.)

Clapper rails have a reputation for being shy but this is probably because they’re so hard to find.  They rarely fly so you won’t see them in the air.  Instead they prefer to walk through very dense saltmarsh vegetation looking for their favorite foods: crustaceans, insects, small fish and even bird eggs.

Though hard to find, it’s common to hear their calls when they’re courting.  They probably make so much noise because they can’t see each other.

Steve Gosser was lucky to see a whole family of clapper rails in coastal Maryland.  I’m glad he had his camera ready!

(photo by Steve Gosser)

4 responses so far

Aug 14 2011

Little Potatoes

Published by under Plants


Yesterday I found this plant blooming next to the Youghiogheny River at Ohiopyle State Park.

This is groundnut (Apios americana), a perennial vine with irregularly shaped reddish-brown flowers.  The vine lacks tendrils so the entire plant wraps itself around nearby vegetation.  I found it climbing Joe Pye-weed.

You might know groundnut by one of its other names — hopniss, pig potato, potato bean or Indian potato — most of which refer to its edible tuberous roots that are high in protein and look like small potatoes growing in a chain.  Each one is about the size of your thumb.

Native Americans taught European settlers that they could eat groundnut but neither of them bothered to domesticate it the way the potato was domesticated in Peru.  If they had, we’d probably be eating groundnuts today.

p.s. An attempt has been made to domesticate it.  Maybe we’ll eat it in the future.

(photo by Dianne Machesney)

4 responses so far

Aug 13 2011

Giant on Ironweed

Published by under Plants


Here’s a beautiful picture of an unusual butterfly from Marcy Cunkelman.

It’s a giant swallowtail (Papilio cresphontes), the largest butterfly in the U.S. and Canada with a wingspan of 3.9 to 6.3 inches.  Not only is it large but it’s a fast flier with a hopping flight pattern.

In the photo you see its light-colored underside but it looks completely different from the top: dark brown with yellow stripes.

I’ve never seen a giant swallowtail and I’m sure I’ve overlooked its caterpillar because the larva looks like bird poop (click here to see).

Marcy was lucky.  She glanced out the window, saw the butterfly, and ran outdoors with her new camera.  The butterfly obliged by pausing on ironweed while she took its picture.

Nice!

(photo by Marcy Cunkelman)

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