Category Archives: Tenth Page

Unlikely Relatives

Tenth Page, Water and Shore
Pied-billed grebe (by Chuck Tague) and flamingo (from Wikimedia Commons)

4 January 2013:

If you were looking for the flamingo’s closest living relative it’s unlikely that you’d ever pick a grebe, but it’s true.

As DNA testing became perfected in the late 20th century, scientists naturally turned their attention to birds.  What does bird DNA show about their relationships?  The studies told us more than we bargained for.

Pictured above are a pied-billed grebe (Podilymbus podiceps) and an American flamingo (Phoenicopterus ruber).   Based on DNA research (van Tuinen, et al, 2001) the families of grebes (Podicipediformes) and flamingoes (Phoenicopteriformes) are each other’s closest living relatives.  Studies indicate they have a common ancient ancestor which is now extinct.

This finding was only the tip of the iceberg.  In many cases DNA testing confirmed previous taxa but in some cases unrelated birds were shown to be related, previously related birds were pulled asunder, taxonomic order had to be revised and scientific names were changed.

This makes for an ever-changing array of new field guides with new names and new orders.  The black-bellied whistling duck is now the first bird on the ABA Checklist.  Years ago the common loon came first.

I love all this new information but renaming the warblers was more than I could bear.  I wish they had tossed out the name Setophaga and called them Dendroica.

(Inspiration for this Tenth Page is from page 70-73 of Ornithology by Frank B. Gill.    Pied-billed grebe photo by Chuck Tague.  Flamingo photo by Aaron Logan on Wikimedia Commons)

Feather Facts

Bird Anatomy, Tenth Page

Feathers are to birds as hairs are to mammals .. but not quite.

Here are some feather facts to ponder.

  • Feathers, like hair, are dead structures that have no nerves and cannot change or heal themselves if damaged.
  • Our hair grows continuously.  Feathers grow to completion and then stop, so they must be replaced when worn out.
  • The follicles that hold feathers in the skin have muscles that grip the feathers so they don’t fall out.  Anyone who’s plucked a chicken knows these muscles are strong.
  • In some birds, such as nightjars, the follicle muscles let go when the bird is frightened suddenly.
  • A new feather literally grows under the old one and pushes it out of the follicle.
  • Contour (body) feathers are symmetrical and so are their follicles.  Flight feathers are lopsided: narrow on one side of the rachis (shaft) compared to the other.  Flight follicles are lopsided too.
  • The same feather follicle can produce differently colored feathers at different times of year — for example colorful feathers for the breeding season and drab ones for basic plumage.  Imagine if our hair could do that! We could automatically change our hair color in the spring.

Resources: Anatomy: Parts of a Feather.

(Inspiration for this Tenth Page is from page 90 of Ornithology by Frank B. Gill. Photo from Wikimedia Commons; click on the image to see the original)

In Response To Daylight

Tenth Page

20 December 2012:

Tomorrow is the shortest day of the year, the winter solstice, when Pittsburgh will have only 9 hours 17 minutes of daylight compared to 15 h 4 m during the summer solstice.

This annual ebb and flow of daylight is an important cue for organisms that live in the temperate zone.

Birds, animals, plants, fungi and even blue-green algae all have internal clocks approximately 24 hours long.  Humans have long clocks: 24 hours and 11 minutes plus or minus 16 minutes.  Some birds have short clocks that run less than 24 hours.

The discrepancy doesn’t matter because our internal clocks reset every day in response to daylight.  In constant dim light we have no cues.  Experiments with common chaffinches show that their circadian clocks drift until their “days” are only 23 hours long in the absence of sunrise and sunset.

Birds also have circannual clocks that trigger their annual cycles of molt, migration and reproduction.  These clocks respond to the shorter days of fall and winter and the lengthening days of spring and summer.

After the breeding season birds’ reproductive organs shrink, an adaptation for flight that lightens their load during most of the year.  The shrinking is triggered by the decreasing light of fall and winter days.  After the winter solstice, the increasing photoperiod triggers their organs to grow in preparation for breeding.

Experiments with juncos show that they require a winter solstice for this to happen.  If the photoperiod increases without first decreasing, their reproductive organs don’t grow.

Our birds need the solstice to set their clocks.

(Inspiration for this Tenth Page is from page 250 of Ornithology by Frank B. Gill.    Photo from Wikimedia Commons; click on the image to see the original)

Plumage Basics

Bird Anatomy, Tenth Page, Water and Shore

Birds molt at least once a year to replace worn out feathers.  This process permits them to wear different plumages.

Some birds, like the American robin, look the same before and after.  Others radically change their appearance by replacing their fancy breeding feathers with plainer plumes.  Male scarlet tanagers are an extreme example:  They’re red while breeding and green while not.

Molt and plumage terminology was standardized in 1959 by Humphrey and Parkes who divided plumage names into three main types. (*)

  • Juvenile plumage is worn by young fledged birds.
  • Basic plumage is what birds acquire during their annual post-breeding molt.  We often call this “non-breeding” or “winter” plumage but these terms are inaccurate.  Adult robins are always in basic plumage even when they’re breeding, and “winter” describes the weather North America is experiencing while the bird is away.  To South American birders, a green scarlet tanager is in summer plumage.
  • Alternate plumage is optional.  Some birds don’t undergo a second molt but those who do put on their finest feathers in time for the breeding season.  This is often called breeding plumage.

In some species it takes several years for the young to mature so they progress through as many plumage cycles as it takes to become adults.  Young ring-billed gulls go through three cycles:  Basic 1, Alternate 1, Basic 2, Alternate 2, Basic 3, Alternate 3. Gulls are complicated.

American avocets aren’t quite so complex.  They molt their wing feathers once a year but change out their head and neck feathers twice a year from basic plumage (white) to alternate plumage (ochre) for the breeding season.

The avocets above are lined up in perfect sequence during their post-breeding molt in August.  The bird standing on the left is closest to basic plumage, the bird on the right is closest to alternate plumage, and the bird in the middle is halfway between.

 

Below, another flock has the lead bird closest to alternate plumage and the trailing bird closest to basic.

Look closely at each bird and you can see that the wings of the 1st, 3rd and 4th birds have ragged trailing edges because they’re molting their wing feathers.  The 2nd and last birds have perfect wings, so my guess is that they’re juveniles.  Juveniles don’t molt their fresh new wing feathers until they’re a year old.

When avocets have completed their molt into basic plumage their heads and necks are gray-white like this bird photographed in September.

 

Experts in molt and plumage can probably tell the age of these birds by their appearance.

Not I.  Aging shorebirds by plumage is my final frontier.

(Inspiration for this Tenth Page is from page 110 of Ornithology by Frank B. Gill.
All photos by Bobby Greene)

 

(*) If you’re a plumage expert, please feel free to correct me.  I’m still learning!

P.S. TO PEREGRINE FANS:  Molting is a wonderful thing.  Last May the male peregrine at Pitt, E2, chased off an intruder but not before this opponent damaged one of his primary feathers.  This gave him a “hole” in his wing.  Over the summer he completed his annual pre-basic molt and grew all new feathers.  Now his wings are perfect.  No gap.

Hiding By Voice

Tenth Page, Vocalizations
Female northern cardinal (photo by Cris Hamilton)

Have you ever noticed how hard it is to find a bird when it’s making an alarm call?  And how easy it is to find when singing?

It’s not just that birds hide when alarmed and sing out in the open.  They change their tune to conceal or reveal.  They know that the “physical structure of a sound affects the ease with which a listener — predator or neighbor — can locate its source.” (*)

Northern cardinals are a great example of this principle.

When they’re hiding in a thicket, their call is a thin, faint, high note.  The alarm call’s narrow frequency range makes it really hard to pinpoint.  Click here for an example.

By contrast, when they’re announcing their presence or guarding their territory the sound is rich and variable in a wide frequency range.  This gives it a lot more “hooks” for our ears to grab onto.  Here’s an example of their song and contact calls.

So when birds are warning each other of danger, there’s a reason why you can’t find their location.  They’re hiding by voice.

(photo by Cris Hamilton. Inspiration for this Tenth Page is from page 220(*) of Ornithology by Frank B. Gill.)

Form, Function, and a Quiz

Bird Anatomy, Quiz, Tenth Page

All birds have feathers, wings and two legs but they certainly don’t look alike, not even in silhouette.

Birds in the same family can look very different.  Take sandpipers (Scolopacidae) for instance:

  • Sanderlings are small sandpipers with short legs and a short pointy bill.
  • Whimbrels are more than twice the sanderlings’ size with relatively short legs and a long down-curved bill.
  • The critically endangered spoon-billed sandpiper is smallest of all with short legs and a spoon-tipped bill.

Why are they so different?  Their features have evolved to match their lifestyles.

  • Sanderlings chase waves to catch invertebrates tossed on sandy beaches.  They need to be quick so it’s important to be close to the ground and able to pick up prey quickly.
  • Whimbrels use their long curved bills to probe the mud of salt marshes and tidal flats to find crabs and invertebrates.
  • Spoon-billed sandpipers sweep their bills side to side in shallow water to capture prey.  Like the roseate spoonbill their lifestyle has shaped their bills.

In architecture, form follows function.  In birds their form happened first, then the birds with better features survived.

 

And now for a Quiz!

Every time I look at the silhouettes, I find myself trying to identify the birds.  There are 26 individuals and 3 flocks in the image.  How many of the silhouettes can you identify?

Tips:  I’ve numbered the individuals and marked the flocks with letters below. Assume each flock is made up of the same species.  Some of the 26 individuals are repeats.  If you can’t identify the exact species, name the bird by group, as in “gull.”

Post your answers in the comments.  Good luck!


(Inspiration for this Tenth Page is from page 10 of Ornithology by Frank B. Gill.  Bird silhouettes from Vectorilla.com. Click on the image to see the original)

How Birds Improved Upon Their Past

Bird Anatomy, Tenth Page


Last week I wrote about the Urvogel Feather of Archaeopteryx lithographica, the oldest feather ever found.  Now that I’m beginning the Tenth Page series I’ve discovered that page 30 of Ornithology has a neat comparison of Archy’s skeleton to that of modern birds.

Archaeopteryx lithographica is recognized as a link between dinosaurs and birds because he has features of both.  Like dinosaurs he has**:

  • jaws with sharp teeth
  • three fingers with claws
  • a long bony tail
  • hyperextensible second toes that are “killing claws”
  • feathers, which also suggest homeothermy (This characteristic is rather self-fulfilling in that dinos were not thought to have feathers until Archy was discovered.)
  • and various dinosaur skeletal features.

Like birds he has:

  • flight feathers, the asymmetrical feathers on his wings
  • broad wings
  • hollow bones
  • a furcula, the “wishbone”
  • and reduced fingers.

But as a bird he’s not quite there yet.  Modern birds have skeletal adaptations that make flight much easier than it must have been for Archy.  This is evident in a skeletal comparison.

Page 30 of Ornithology describes how modern birds improved on Archaeopteryx lithographica’s features:

  1. Skull: In modern birds the braincase is expanded and the bones are fused.
  2. Hands: Most of the bones are fused
  3. Pelvis: Bones are fused to make a sturdier structure
  4. Tail: Bones are fused, the tail is shorter
  5. Sternum: Expanded to a large keel for attaching the flight muscles
  6. Rib cage: Has cross-struts (“horizontal uncinate processes”) for strength.

So, if you have a lot of time to improve your flight abilities — say 150 million years — this is what you get.

Inspiration for this Tenth Page is from page 30 of Ornithology by Frank B. Gill.

(credits:
** The dino list is quoted from the Wikipedia article on Archaeopteryx.
Photo of Archaeopteryx lithographica, Solenhofener specimen from Wikimedia Commons.  Skeleton of modern bird from Illustrations of Zoology by W. Ramsay Smith and J S Newell, in the public domain via Wikimedia Commons, red annotations added by Kate St. John.  Click on the images to see the originals.)

New Series

Musings & News, Tenth Page

As usual, winter is a slow time for observing nature so my blog ideas are pretty thin. However, your encouragement on my Bird Anatomy series (20 Nov 2009 to 25 Feb 2011) has inspired me.

This Friday I’m going begin a new series called Tenth Page.

Though it’s loosely based on bird anatomy, Tenth Page is named for its subject matter.  My rule is that I must open Frank B. Gill’s Ornithology at a page number evenly divisible by 10.  Whatever is on that page will be fodder for a blog.

I’ve already checked all the tenth pages in my copy of the book and discovered that there are 3 blanks in the #10-series.  Aha!  Those will be wildcard subjects in which I can pick any old page I please.

And I won’t be predictable.  That would be boring.  Not 10, 20, 30 for me!  To keep myself interested I’m more likely to dip in at random and choose a tenth page that inspires me.

As a result, you won’t be able to guess my subject by reading the book — and neither will I.

Stay tuned for Tenth Page, coming this Friday.

 

(photo by See-ming Lee via Wikimedia Commons. Click on the image to see the original)

 

p.s. The photo above has a series of its own.  Taken by See-ming Lee at Vinegar Hill, New York, NY on 30 Dec 2007, it’s been posted to Wikimedia Commons for use in a series of blogs.  Click on the image to see the original photo and the list of blogs that have used it.  (Mine is there too.) Pretty cool!

p.p.s.  On the Bird-thday blog Peter and Stephen suggested I write about bird calls.  Be watching for bird calls sprinkled throughout the year.

Wearing Black-n-Gold!

Bird Anatomy, Bird Behavior, Tenth Page


Did I tell you I live in Pittsburgh where the Steelers are playing the AFC Championship game this Sunday?

It’s a rare day that bird anatomy is related to the Steelers, but today is that day.

For many weeks I’ve been using Frank B. Gill’s Ornithology to inspire Friday’s anatomy lesson.  Rather than read the whole book I open the index at random and with my eyes closed I point to a word.  Then I look up that word and find something interesting to write about.  Today’s word was “Yellow-throated Brush Finch, page 328.”

Page 328 discusses the advantages of multispecies flocking.  Many species form mixed flocks because they get more to eat when there are many eyes watching for danger.  In Pennsylvania we often see mixed flocks in winter led by titmice and chickadees.  The leader species are dominant, the others follow.

Some birds go one step further.  Ornithology describes how in some mixed flocks “unrelated bird species have similar plumage color patterns that promote flock cohesion.  Subordinate species increase acceptance by resembling dominant flock members.”

These distinctive color patterns are called flock “badges.”

The yellow-throated brush finch (bottom right) is a member of one of these unusual flocks in Western Panama.  His compatriots are all black and yellow.

As I assembled this photo, I suddenly realized that the brush finch and all his friends are wearing Steelers colors.  It’s a whole flock of black-n-gold birds!  How cool is that?!

So this is what we look like in Pittsburgh right now.  We’re wearing our Flock Badges, black-n-gold!

.

(composite photo credits, top left to right, then bottom left to right:
1. Slate-throated Whitestart: Corey Finger on 10000birds.com
2. Sooty-capped Bush Tanager: Wikipedia
3. Yellow-thighed Finch: Wikimedia Commons
4. Collared Whitestart: Jan Axel on janbirdingblog.blogspot.com
5. Silver-throated Tanager: Kent Fiala’s Website
6. Yellow-throated Brush Finch: Atrevido1 at Solo Aves on Flickr)