Archive for December, 2010

Dec 31 2010

Anatomy: W and Z

Published by under Bird Anatomy


At the end of the year I’m at the end of the alphabet, but these letters are actually about the sex chromosomes of birds.

Mammals have sex chromosomes called X and Y which determine the sex of the individual.  A mammal embryo is born female if it has two of the same chromosomes: XX.  It’s male if it has two different chromosomes:  XY.

Birds are similar but very different.  Like mammals they have two sex chromosomes but the structure and origin of these chromosomes are so different that they’ve been labelled W and Z.  They also combine in the opposite way to determine the sex of the individual.  Female birds have two different sex chromosomes: ZW.  Male birds have two of the same:  ZZ.

In birds, unlike mammals, nearly every cell has its own sexual identity so if an aberration occurs during the first cell division of a bird’s fertilized ovum, the resulting individual can be half-male and half-female, neatly divided down the length of its body.  These unusual individuals are called “bilateral gynandromorphs.”

Pictured above are three evening grosbeak specimens from the Smithsonian*.  One is male, one is female and the third (at the top of the photo) is a bilateral gynandromorph.  It’s right half is dull like the female.  Its left half is bright yellow like the male.  This sexual difference continues inside its body where its organs are female on the right and male on the left.

Gynandromorphs are rare but have been documented in a variety of bird species.  It’s not seen in humans because most of our embryonic cells are sex-neutral.  Hormones, not the individual cell, govern our sexual characteristics.

Click here to see more photos of bilateral gynandromorphs.

(photo from Flikr by ap2il, licensed under the Creative Commons License 2.0.  Click on the image to see the original where one of the keywords is Smithsonian *hence my assumption on the location of these specimens.)

4 responses so far

Dec 30 2010

Quiz: Who else can fly like this?

Published by under Quiz


Quick!  Name an animal — not a bird — that can fly like this.  Here are some clues.

  • This animal doesn’t flap, but it does fly.
  • It has better lift and less drag than many insects.
  • It’s lift ability is the same as for hawks and wood ducks.
  • The longest time it’s been recorded aloft is 45 seconds.
  • It can travel as much as 1,300 feet in one flight.  That’s more than 4 football fields!
  • And, with the help of the wind, it can speed along at 43 miles per hour.

Leave a comment with your answer.

(If you’re really stumped, the answer is at this link.)

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

7 responses so far

Dec 29 2010

Winter Weeds: Spreading Dogbane

Published by under Winter Weeds & Trees


Spreading Dogbane (Apocynum androsaemifolium) is one of my favorite winter weeds because it’s easy to identify and has such a cool name.

It’s a shrublike, woody perennial that stands one to four feet high with widely branching stems.  In snow cover its seed pods stand out.  Dark brown, three to eight inches long, and very narrow, they split open lengthwise to reveal seeds with fluffy fiber tufts similar to milkweed.

Shown above are two winter views of its pods.  On the left the unopened pods dangle in pairs from the stem.  They’re as long as your hand, or longer.  On the right the pods have burst open.

Because dogbane and milkweed are related, they share another characteristic as well:  both have milky, poisonous sap.  That’s how dogbane got its unusual names.  Dogbane means “dog poison,” Apocynum means keep “away from dogs.”  Why all the focus on dogs?  I don’t know.  It’s poisonous to people and livestock, too.

In winter dogbane is easily confused — at least by me — with closely related Indian Hemp, so named because its tough fibrous bark was used by Native Americas to make rope and twine.

Look for spreading dogbane in fields and thickets.  If you’re in a marsh or at the shore, the plant may be Indian hemp.

(photos by Marcy Cunkelman)

4 responses so far

Dec 28 2010

A Taste of What We Never Knew

Published by under Beyond Bounds


Last Thursday at Wakodahatchee Wetlands, Florida I heard the screech of birds calling in flight.  The sound reminded me of terns so I searched the sky for large white birds but couldn’t find any.  Then I remembered.  That’s the sound of parakeets.

In western Palm Beach County escaped or released monk parakeets (Myiopsitta monachus) have gone wild.  In the four hours I spent at the wetlands I counted at least 20 flying by but they never landed.

Later at Boynton Beach Inlet I found a large flock of black-hooded parakeets (Nandayus nenday), native to South America and pictured above.  They loafed on the wires above the park and frequently commented on the world going by.  Some perched in pairs shoulder to shoulder, leaning against each other and allo-preening.  When other parakeet flocks approached, the large flock screeched a greeting so the others would join them.  Eventually the flock numbered at least 75 birds.  They grew restless and circled up and away.

Two hundred years ago there were parakeets in Pennsylvania, but no more.  When Europeans first came to this continent the Carolina parakeet ranged from New York to Florida, from eastern Kansas to the east coast.  But the birds quickly left when settlers arrived on the scene, even when suitable habitat remained.  Perhaps the birds were smart to leave.  The settlers killed them for their beautiful feathers and as fruit-tree pests.

Eventually the pressure of human encroachment took its toll on the Carolina parakeet.  By 1878 the only colonies east of the Mississippi were in remote parts of Florida.  By 1918 the last known bird died at the Cincinnati Zoo.

Interestingly the monk parakeet is winter-hardy and has established feral colonies as far north as Brooklyn (NYC), Chicago and Connecticut.  They could live in Pennsylvania but the state considers them agricultural pests and it is illegal to sell or own them.

And so we will never know what it was like when wild parakeets roamed Pennsylvania.  In Florida you can get a taste of it.

(photo of black-hooded parakeets in Brazil, from Wikipedia.  Click on the photo to see the original)

5 responses so far

Dec 27 2010

Magnificent!


Wow!  Saw this bird at Boynton Beach Inlet around noon last Thursday while I was in Florida visiting my family.  He was all black without the red gular throat skin, a non-breeding male.

Magnificent frigatebirds are large tropical sea birds unlike any other.  With a 7-foot wingspan and a long forked tail they are powerful and graceful in flight, so good at flying that they can ride out a hurricane.  

On land they are far from graceful.  Their legs are so short that they can’t walk so they use their strong toes and claws to perch on trees, woody shrubs, boat rigging or whatever is convenient. They never land on the ground and very, very rarely land on water.

Frigatebirds got their name because pirates sailed in frigates.  Though they get most of their meals by catching fish and squid near the ocean’s surface, frigatebirds are known for stealing food from other seabirds whom they harass until the victims regurgitate the fish held in their throats.  The frigatebirds then dive and catch the meal before it hits the ocean.

This is only the second time in my life I’ve seen a magnificent frigatebird, so for me this was a rare sighting.  Frigatebirds don’t breed on the coast of Florida (except in The Keys) but they travel widely … because they can.

Magnificent!

(photo from Wikipedia by John Picken. Click on the image to see the original.)

2 responses so far

Dec 26 2010

Where’s Willow?


How many birds do you see in this picture?  If you were a gyrfalcon you’d know right away.

These are willow ptarmigan (Lagopus lagopus), a non-migratory grouse that lives in the open tundra and moorland of Scotland, Scandanavia, Siberia, Canada and Alaska.

Willow ptarmigan are masters of disguise.  In summer they are brown and speckled like the vegetation they eat and hide in.  In winter they molt into white plumage to match the snow, and between the seasons they’re brown and white like patchy snow and dirt.  Willow ptarmigan have to be well camouflaged because so many predators eat them including foxes, wolves, owls, peregrines and gyrfalcons.

How did willow ptarmigans get their name? 

“Willow” comes from what they eat in winter: the twigs and buds of willows and alders.

“Ptarmigan” comes from the Gaelic word “tarmachan” which means to grumble or croak and describes the sound these birds make.   Tarmachan has no “P” but in the late 17th century somebody put a P at the front of the word to make it look Greek and scientific.  By the early 19th century the P stuck and became the accepted spelling of the word.

Did you find three birds in this picture?  If so, you probably followed their tracks.  Ptarmigan know their tracks are a dead giveaway so they sometimes fly directly to a hiding place and burrow into the snow.  Then it’s really hard to find them and you’ll certainly be wondering, “Where’s Willow?”

(photo by Ansgar Walk from Wikimedia Commons. Click on the photo to see the original where you can also see wing marks in the snow.)

4 responses so far

Dec 25 2010

Merry Christmas!

Published by under Books & Events


For a respite from the cold, visit Phipps Conservatory. Their Winter Flower Show runs until January 9.

(photo taken at Phipps Conservatory in 2008 by Dianne Machesney)

2 responses so far

Dec 24 2010

Are you the “Partridge in a Pear Tree?”


The Twelve Days of Christmas repeats the refrain that my true love gave to me a partridge in a pear tree. 

Being a birder I began to wonder, “What species of partridge are they talking about?”

My first thought was that Twelve Days is an English song so the partridge must be from England, but it’s more complicated than that. 

The words were published in England in 1780 but the tune is much older and is probably French.  The birds in the song might be English or French.  So who’s the partridge?

Probably this one.  The red-legged partridge is now common in England but was imported from France for hunting purposes, so he fits the bill.  One other trait makes him a likely candidate.

The gifts in the Twelve Days of Christmas are fantastic and extravagant.  (Imagine receiving eight maids-a-milking!)   The “partridge in a pear tree” is fantastic too because partridges are terrestrial birds who only fly when they have to.  It would be unusual to find one in a pear tree and I suspect it would be there only because it was frightened.

Of all the partridges in England and France, this one is the most likely to perch in a tree. 

So he’s probably the one my true love gave to me.

(photo from Wikipedia)

7 responses so far

Dec 23 2010

Behind the Scenes of “Hummingbirds”

Published by under Beyond Bounds


This video is so cool you really must see it.

It’s a behind-the-scenes look at the making of PBS’s NATURE show Hummingbirds: Magic in the Air.  In it the producer describes how they filmed these tiny birds and what they learned.

Bird watchers and photographers can relate to their experience, how hard it was to capture what they were looking for and how rewarding it was when they did.  I felt a kinship when the team spent days trying to get a split-second video of a hummingbird catching an insect.

And what an expensive video endeavour!  You’ll be amazed by NATURE’s cameras and lenses.

So click on the video and enjoy.  You’ll be dazzled.  I guarantee it!

(video from PBS NATURE)

p.s. If you didn’t see Hummingbirds: Magic in the Air when it premiered last January 10th on PBS’s NATURE or this month when WQED re-broadcast it during our year-end fund-raising effort, you can view its entire 50 minutes online here.

10 responses so far

Dec 22 2010

Winter Weeds: Queen Anne’s Lace

Published by under Winter Weeds & Trees


Queen Anne’s Lace (Daucus carota) is easy to find in summer and winter because it grows abundantly in meadows, along roadsides and in waste places.

In winter its umbel flower head curls inward, holding the seeds like a nest inside.  The tiny fruits are very interesting.  They’re ribbed with rows of bristles and pop open on their long edge.  This flower is holding the fruits and some snow as well.

Queen Anne’s Lace is in the Parsley family.  Its two to three-foot stems are grooved and slightly hairy and its leaves — if still present — are many-branched and even more finely divided than parsley.  If you’ve seen the leaves in summer they remind you of carrot tops and that’s exactly what they are.  Daucus carota is the same species as our garden carrot and has a yellowy-white root.  We eat carrots in the first year of their biennial life so we never see them flower.

Smell the leaves and you’ll get a whiff of carrots, parsley and parsnips.  But be careful.  Know your plants before you handle, dig or taste them.  Poison Hemlock, the plant that killed Socrates, is also in the Parsley family and resembles Queen Anne’s Lace in many ways. 

(photo by Marcy Cunkelman)

2 responses so far

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