Monthly Archives: October 2009

Heading South

Migration, Water and Shore

Canada Geese on migration (photo by Cris Hamilton)
Canada Geese have been moving south for several weeks now.  Yesterday morning I saw hundreds of them resting near Millers Ponds at Pymatuning.  These geese are true migrants, probably just arrived from their breeding grounds in the southern James Bay region of Canada.

I mention them as migrants because in Pennsylvania we have plenty of resident geese.  It seems hard to believe but the subspecies Branta canadensis maxima (Giant Canada Goose) was nearly extinct in 1900 due to overhunting and habitat change.  Many states conducted reintroduction programs to help the geese along.  The birds so did well that there are now nearly 290,000 resident maxima Canada geese in Pennsylvania and their population keeps growing despite a special hunting season instituted in 1992.

Why don’t our resident Canada geese migrate? 

Geese travel in family groups which collect at staging areas to join larger flocks.  The young geese learn their migratory paths from their parents.  If their parents don’t migrate the whole family stays put.  I’ll bet the geese that were reintroduced had no one to teach them to migrate so they and their descendants became residents.

Not so with the geese at Pymantuning.  By 5:00pm when I left Linesville all the migrant geese were gone.

(photo by Cris Hamilton)

Fall Colors: Cranberry Viburnum

Plants & Fungi

Cranberry Viburnum (photo by Tim Vechter)
Plants have many strategies for dispersing their fruits. Here’s one that’s quite ingenious.

First, wrap the seed in a very sour, very hard pulp.  Then wrap the pulp in a colorful covering that lasts a long time.  The fruit is so hard and sour that no one will eat it.  So why bother making fruit?

Ah, but wait.  As fall turns to winter, frost breaks down the pulp and takes the extreme sour edge off the fruit.  At this point the birds who remain through the winter have something to eat.

Theoretically this strategy of feeding winter birds would guarantee the seeds don’t disperse far, but the plant has spread thanks to people.  In colonial times we figured out how to add sugar and make jams and jellies from it, and we like its color so much that we plant it as an ornamental.

Quite a success story for Cranberry Viburnum (Viburnum trilobum), a beautiful but sour fruit.

(photo by Tim Vechter)

On Hold

Weather & Sky

This was supposed to be my big day for visiting the Allegheny Front Hawk Watch near Central City, PA but the weather in the mountains and in northern Pennsylvania is dreadful right now.

Yesterday’s news of 4.5 inches of snow in State College — and more on the way — sent everyone scrambling to cancel outdoor activities across the state.  Here in Pittsburgh where it’s cold and rainy today’s neighborhood cleanup was canceled too. 

Everything is on hold.  So is migration.

I hope the birds who are waiting out the storm survive these days of bad weather.  It will be hard for them to find something to eat under all that snow. 

(photo of snow damage in State College by Jesse Ferrell, linked from his Accuweather community blog site.  Click here for more of Jesse’s photos of the State College snowfall.)

Mortality

Peregrines

Two peregrine fledglings at Univ of Pittsburgh (photo by Kimberly Thomas)Sad news.

Yesterday the body of a young female peregrine born at the University of Pittsburgh this spring was found in the chimney at Webster Hall.  The green tape on her USFW band indicated she was the same bird who’s eating in this picture taken by Kimberly Thomas on June 9.

Of the four peregrines hatched at Pitt this spring, she was the smallest female and the one who stayed closest to home.  She visited the nest box on June 29 long after her siblings had stopped going there.

When she was found she’d been dead for a while; her body had dried out.  The maintenance man at Webster Hall thought she may have died of carbon monoxide poisoning because he often saw her perched on a rooftop smokestack.  Alas, she chose a bad place to hang out.

Unfortunately she’s not the only juvenile peregrine from the Pittsburgh area to die this fall.  In early September I learned that one of the three young peregrines born at the Monaca bridge died on August 30 when he struck an airplane at Pittsburgh International Airport.  He was probably hunting the smaller birds attracted to the open area near the runways.

Research tells us that more than 60% of young peregrines die in their first year – many of them before they leave home – but it’s always sad to learn the details.

(photo by Kimberly Thomas)

Sharp-shin

Birds of Prey

Sharp-shinned Hawk (photo by Kim Steininger)

With a look that strikes terror in the hearts of small birds, this sharp-shinned hawk hunted at Kim Steininger’s backyard feeders on a snowy winter day.

Kim was lucky to see him.  Though they’re present year-round in Pennsylvania and are the most numerous raptor at hawk watches this month, sharp-shins are very unusual in my Pittsburgh neighborhood in winter.

The last time I saw a sharp-shinned hawk was quite recent, though.  Last Monday I sat on top of a cliff called Giant Ledge in the Slide Mountain Wilderness of the Catskill Mountains and gazed to the east.  It was a chilly overcast day with no bird activity.  The maple and beech forest below me was clad in reds and yellows.  I could see for miles.  No birds.

Then one small hawk rose from the valley floor 1,000 feet below.  He circled to gain altitude and in a matter of minutes rose past my line of sight until he was above all the mountains.  Then he set his course and disappeared to the south.  Flap, flap, glide.

(photo by Kim Steininger)

Disease links T.Rex to raptors

Birds of Prey, Peregrines

Hypothesized Trichomonas-like infection in T. rex (Illustration by Chris Glen, The University of Queensland from plosone.org)For years people believed the holes in the jawbones of many Tyrannosaurus rex skeletons were evidence of fighting, even though they were too round and perfect for violent combat.  Recently paleontologists re-examined the holes with a new theory in mind and published their findings on PLoS One.

What lead them to the discovery was this thought:  Where have we seen holes like this before?  We’ve seen them on the jawbones of modern day birds of prey who suffered from a common avian parasitic infection called trichomoniasis.

Raptors, including peregrine falcons, catch trichomoniasis by eating diseased prey.  Peregrines are susceptible to it because they eat pigeons who carry the disease without showing symptoms.  Trichomoniasis invades the mouth and throat causing lesions which eventually penetrate to the bone.  The lesions block the throat making it hard to swallow and the raptor dies of starvation. 

When the paleontologists compared the holes on the tyrant dinosaur jawbones to those of raptors who had trichomoniasis, everything matched up.  The illustration at right shows how the infection would have looked on Tyrannosaurus rex with lesions both inside and outside mouth.  (Ewwww!)  Just like raptors, the tyrant dinosaurs would have caught it through feeding on diseased meat or by snout to snout contact. 

To me, the cool part of this discovery is that modern day birds are close enough to T.rex that they still suffer from a tyrant dinosaur disease. 

And it solved another mystery for me.  When peregrine falcon chicks are banded, the veterinarians always swab their throats with a long Q-tip to test for disease.  Now I know at least one of the diseases they’re looking for.

For more information on this discovery, click here or on the illustration to read the original article at PLoS ONE. 

(Illustration of trichomoniasis in T.rex, based on photographs of living birds suffering from the disease and bird necropsies, by Chris Glen, The University of Queensland.  Article Citation: Wolff EDS, Salisbury SW, Horner JR, Varricchio DJ (2009) Common Avian Infection Plagued the Tyrant Dinosaurs. PLoS ONE 4(9): e7288. doi:10.1371/journal.pone.0007288)

Fall Colors: Maple and Ash

Phenology, Trees

Fall colors at Latodami Nature Center (photo by Dianne Machesney)
Fall is really here.

Right now our maples are showing off their oranges, reds and yellows while our ash trees wear pastel yellow and pale violet.

Soon the maples and ashes will lose their leaves but we’ll get a second burst of color from the oaks — ochre, rust and burgundy.

Enjoy it now.  The trees will be bare in November.

(photo by Dianne Machesney of Latodami Nature Center at North Park)

Orion Time

Phenology, Weather & Sky
Orion animation by Michelet B via Wikimedia Commons
Orion animation by Michelet B via Wikimedia Commons

11 October 2009

Winter is coming.  Orion the Hunter is back.

Hidden all summer, the Orion constellation is visible again in our southern sky.  I first noticed him last week, just before dawn.

You can pick out his features in the photo at left.  The line of three stars in the middle is his belt, the vertical line below that is his dagger and the four stars at the four corners mark his shoulders and knees. The unusual red star at his top left shoulder is Betelgeuse.  Click here to see how the Ancient Greeks made this pattern into a hunter.

Orion lies on the celestial equator so he’s visible in each hemisphere in winter. He’s one of my favorite constellations but truth be told he’s one of the few I can see.  My neighborhood is bad for star gazing due to city lights and Pittsburgh’s frequent cloud cover.  If the Ancient Greeks had seen as few stars as I do, they wouldn’t have named so many constellations.

Right now Orion is in the south but by January he’ll be at his best.  Meanwhile he has a special claim to fame this month.  On October 21 the Orionid meteor shower will flash in the space between Orion and Gemini, above and left of Betelgeuse.

So keep looking up.  Even at night there’s always something to see.

(Orion animation by Michelet B via Wikimedia Commons; click on image to see the original)

Grackles on the move

Migration, Schenley Park

Flock of Brown-headed Cowbirds (photo by Chuck Tague)
This year is different.

We usually don’t see huge flocks of grackles in Pittsburgh until late October but this year they showed up in the third week of September. I first noticed them in large groups in Schenley Park, gathering in the treetops at dusk.  Since then they’re most noticable on rainy days when they graze on neighborhood lawns and fly low over the road.

Common grackles are diurnal migrants who tend to move in mixed flocks with blackbirds and starlings.  Within the flocks you can pick out the grackles because they have long tails and make a low “chuck” sound as they fly.  Though I’ve looked for other birds among them, the recent flocks are nearly 100% grackles.  When they gather at dusk their “rusty gate” voices are very loud.  Then they take off in unison – an impressive sight.

I wonder why the grackles are early this year.  Is there less food up north than usual?  Is winter coming early?  Do they know something we don’t know?  Probably.

(photo of a flock of brown-headed cowbirds by Chuck Tague.  Are there any grackles mixed in?  Look at their tails.)