Archive for January, 2012

Jan 12 2012


Published by under Songbirds

Just when you've figured out purple and house finches, an orange finch shows up.  Is it a new species?

No.  It's a house finch whose diet shows in his feathers.

Many birds acquire their intense red color from carotenoids in their diet.  Flamingoes are pink because their favored food, brine shrimp, is rich in carotene.  Northern cardinals are brighter red when they eat red fruits.  This is true of house finches too.

The key is what they eat and when they eat it.  A house finch can eat red carotenoid food all year, but if he skips it during his molt his new feathers won't be as red.  House finches molt in July and August.  Back then the orange-colored finch was eating food containing beta carotene, which makes yellow or orange feathers, but not enough red.

Here's a side view of Mr. Orange and Mr. Red.

Pretty as he is, Mr. Orange will have a poorer selection of ladies this spring.  Female house finches prefer the brightest red males as mates so he'll end up with a less favored female.

Fortunately he doesn't have to be orange the rest of his life.  If he eats red carotenoids next summer he'll be much redder next winter.  It will surely improve his love life.

(photos by Marcy Cunkelman)

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Jan 11 2012

Winter Trees: Norway Maple

No discussion of western Pennsylvania's trees would be complete without including the Norway maple (Acer platanoides).

As its name suggests this tree is native to Europe, growing as far north as Norway, south into Greece and Iran, east into Russia.  It was brought to North America as an urban shade tree because it survives well in compacted soil and air pollution.

Unfortunately it survives too well.  The Norway maple naturalized on this continent and easily became invasive because it releases chemicals in the soil that inhibit the growth of underbrush and native saplings.  In addition, native animals and insects prefer to eat North American maples more than this import. With these competitive advantages it's no wonder you can find pure stands of Norway maples with bare ground beneath them.

Normally I recognize Norway maples by their twigs and buds.  The buds are opposite on the stem, reddish and turban-shaped with a slightly larger end bud.  In the photo above, taken in Schenley Park in November, the twig is green with reddish turban-shaped side buds and an end bud that looks like it's opening.  The twig below conforms more closely to the typical description of Norway maple buds.  There are many cultivars in Schenley Park including a variety with purple leaves so my photo may differ for that reason.


Norway maple seeds are easy to recognize because the samaras are nearly 180 degrees apart.  Other maples have "wings" that droop.  You'll see some of these seeds and their stalks on the trees in the winter.


The bark on young Norway maples looks almost smooth, just faintly striped.


On older trees it has narrow stripes and shallow furrows.

Norway maples are easiest to recognize in late fall because they're out of synch with our seasons.  They retain their yellow leaves into mid or late November and lose them only after our native maples are bare.

(photos by Kate St. John except UGA0008518 by Paul Wray, Iowa State Univ and UGA5306048 by Steve Hurst, USDA, both from

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Jan 10 2012

12,000 Crows

Published by under Crows & Ravens

Though they've moved away from residential neighborhoods and are keeping a relatively low profile, Pittsburgh's East End crow roost has attracted some attention lately.

Perhaps it's because sunset is later so we see them during rush hour(*).  Perhaps it's because they're noisy.  Perhaps it's their sheer numbers.

Jack and Sue Solomon counted them on December 31 for Pittsburgh's Christmas Bird Count.  Knowing the crows gathered above Bigelow Boulevard, Jack and Sue waited at dusk in a parking lot opposite Liberty Ave. and 25th Street and watched the hillside above The Strip.   Their estimate?  More than 12,000 crows.

What does that look like?

Sharon Leadbitter filmed them at twilight last Friday.  The first video (23 seconds) shows them flying overhead at Polish Hill.  The video below (2:18) shows them filling the trees above Bigelow Boulevard near the French Fry sculpture.

The flock is raucous only at their staging area.  After dark they fall silent and leave the trees to roost in parts unknown.

If you want to witness this for yourself, January is the time to do it.  Next month the flock will begin to break up.  By March they'll be gone.

(video by Sharon Leadbitter)


(*) The days are getting longer.  Sunset today is at 5:12pm, even later than it was on November 12 when I last wrote about Pittsburgh's crows.

9 responses so far

Jan 09 2012

Looking Backward, Looking Forward

Published by under Peregrines

It feels like a very long time since we watched peregrines nesting on the webcams.  This photo of Dori feeding her chicks at the Gulf Tower is more than eight months old.

But nesting season is not so far away.  This month peregrine couples are getting reacquainted, next month we'll see them courting at the nest, in March the females will lay eggs.

In the meantime (at last!) I've created a slideshow of Gulf Tower nesting highlights from 2011.  The first slide is dated February 22. That's just six weeks away.

Click on Dori's photo for a look backward at Dori, Louie and their five chicks in 2011 and a reminder of what to look forward to next month.

(photo from the National Aviary falconcam at the Gulf Tower, Pittsburgh)

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Jan 08 2012

Sea Ice Land

This amazing block of ice floated to the sea in Iceland.

Its beauty tempted two photographers to try to capture its image.   Click here to see what happened when they set up their tripods.

(photo by Andreas Tille, a featured picture on Wikimedia Commons)

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Jan 07 2012

Otus and Asio

Published by under Birds of Prey

The names of these owls used to be the reverse of each other.

The eastern screech-owl on the left used to have the scientific name Otus asio.  In 2004 the American Ornithologists' Union renamed him to Megascops asio, but his old name is still found on the web.

The long-eared owl on the right is still named Asio otus.

For reasons of symmetry, I wish the AOU hadn't renamed the screech-owl.

"Otus Asio, Asio Otus" was rather fun.

(both photos are from Wikimedia Commons.  Click here to see the original of the eastern screech-owl.  Click here to see the original of the long-eared owl.)

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Jan 06 2012

He Flunked The Mirror Test

Published by under Bird Behavior

Mirror, mirror on the wall
Who's the smartest of them all?

Based on our definition of smartness, humans always win this contest.  One of the ways we measure is this:  Is the animal self-aware?

A classic test for determining self-awareness is the mirror test developed by Gordon Gallup, Jr. in 1970.  In it, an animal is marked with an odorless spot that he can see only when standing in front of a mirror.  If the animal looks in the mirror and grooms or touches the spot, it indicates he understands his own reflection.  He flunks the test if he thinks his reflection is another animal (a rival, for instance) or if he looks behind the mirror to find the other animal.

My cat has flunked the mirror test so often she has stopped looking in mirrors.  She even flunks the birds-on-TV test because she looks behind the television to find the birds.

Only a few animals have passed the mirror test.  These include chimpanzees, gibbons, bonobos, orangutans, dolphins, orcas, Asian elephants, European magpies, pigeons (in a video test) and humans more than 18-24 months old.  Yes, baby humans flunk the test.

Even New Caledonian crows, known to be extremely smart, don't recognize themselves in mirrors but they know how to use them.  A study published last fall showed that New Caledonian crows can see a reflection of hidden food and immediately retrieve the food using the mirror.

Unfortunately most birds flunk the mirror test and some of them waste a lot of time doing it.  During the breeding season birds often mistake their own reflections for rivals and attack mirrors relentlessly.

Mockingbirds don't even wait for the breeding season.  They're territorial all year.  This one attacked his own reflection in a car mirror in November in Florida.  Peggy Sherman took photographs and tells the story here on her Camping Tales blog.

This mockingbird shouldn't feel too bad about flunking.  We humans recognize ourselves in mirrors but most of us still don't understand how mirrors work.  We tend to think that someone else we see in a mirror can see himself in the mirror too.  Nope.  We only see each other.

(photo by Peggy Sherman on her Camping Tales blog)

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Jan 05 2012

Speaking of Calendars…

Published by under Migration

This week we threw away our old 2011 calendars and hung up new ones for 2012.

Here's a calendar that's good every year.

Chuck Tague published a bird migration slideshow for southwestern Pennsylvania on his Nature Observer website last April showing birds on the move every month of the year.

If you're surprised that birds migrate in January, think back to the birds you saw last weekend when the weather was unseasonably warm.  Are you seeing a different mix of birds now that we've had snow and bitter cold?  I am.  (Did your siskins arrive yet?  Mine didn't.)

Even if you saw Chuck's calendar last April, now's a good time for review.  Click on the image to watch the slideshow.

I should put his migrating birds on my appointment calendar so I don't miss them!

(cover slide from Chuck Tague's Migration Calendar slideshow.  Click on the image to see the slideshow)

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Jan 04 2012

Winter Trees: Bitternut Hickory

This one is easy.

It's the only tree in Pennsylvania with a very long yellow end bud (and alternate small yellow buds).  It's the bitternut hickory (Carya cordiformis).

If you live in the southern U.S. the yellow buds resemble the pecan to which the bitternut is closely related.  Both are members of the Walnut family but the pecan produces tasty nuts and the bitternut produces very bitter nuts, so bitter that squirrels avoid them.  Hence its name.

In his 1985 Thornapples essay, A Nut-Gatherer's Compendium, Charles Fergus tells of his excitement at gathering wild nuts before he knew how to identify hickories.  He collected a bucketful of nuts and hammered them open.  Fortunately he tasted one before he spent much time at this activity.  He'd collected a bucket of bitternuts.  So bitter!!

In areas where both trees grow, such as the Mississippi valley, you can distinguish between the two twigs by the bitternut's very long end bud.  Pecan buds are small.

Don't worry that you'll mistake the nuts.  Bitternuts are small and round (one inch diameter) with a pointed tip.  Pecan nuts have the familiar smooth pecan color and oblong shape.

Like all hickories the bark on young bitternuts is gray-brown and smooth but it lacks the stripes found on young shagbarks that will split to become shaggy later in life.

Here's young bitternut bark found in Schenley Park:


The bark on mature bitternuts is said to be thin and tight with interlacing ridges.  This description applies to several other hickories so I didn't illustrate it.  It's so confusing!

Don't bend your brain trying to identify this tree by its bark.  Look at the yellow end bud.  It's easy.

(photos by Kate St. John)

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Jan 03 2012

Really Know Your Feeder Birds

Published by under Songbirds

Did you ever wonder if it's the same chickadee visiting your feeder time after time ... or one of his relatives?  How many trips does he make every day?  Does he stay away longer when the weather's nice?  How long?

These questions puzzled the Cornell Lab of Ornithology so Dr. David Bonter of Project Feeder Watch and a team of students to set up special bird feeders and banded the local feeder birds with radio frequency identification tags.

First invented in the 1970's RFID tags are tiny chips that broadcast unique numbers, one number per chip.  Anyone with a scanner can read the chip's code.  The chips are so small they can be used to catalog merchandise or be inserted just under the skin of pets to identify them if lost.  My cat got her "chip" at the animal shelter before I adopted her.  If she's ever lost a shelter can scan her chip, look her up in the cat database, and reunite us.

Cornell Lab taped RFID chips to the birds' bands, then replaced the perches on their feeders with a coil of wire that can "read" the chips and record the date, time and chip code of each banded bird.  When they download the data they find out who visited the feeder and how often.

They know their feeder birds as individuals now and have the answers to those puzzling questions I asked above.

Watch the video and see.

(video from Cornell Lab of Ornithology)

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