Oct 15 2014

Hybrid Migration

Swainson's Thrush (photo by Matt Reinbold, Bismarck ND, from Wikimedia Commons)

If you’re a Swainson’s thrush of mixed parentage you’ll probably pick a bad migration route.  It’s in your genes.

In eastern North America we see only one subspecies of Swainson’s thrush, the olive-backed (above), but in British Columbia there are two.  The russet-backed subspecies breeds along the Pacific coast and follows the coast to spend the winter in Mexico and Costa Rica.  The olive-backed subspecies breeds in the interior and migrates across the continent and the Gulf of Mexico to winter in South America.

Where their breeding ranges meet the thrushes pair up without regard to these distinctions.  Their hybrid offspring inherit a mixture from their parents, including mixed coloration.

Kira Delmore at the University of British Columbia wondered if the hybridization extended to their migration routes so she tagged hybrid Swainson’s thrushes with light-level geolocators to track their routes.

The data proved that their migration routes are inherited and that those of mixed parentage inherit a blend.  While each parent would have followed the Pacific coast or a safe route across the continent, the hybrids chose novel and dangerous compromises between the two paths.

“Instead of taking well-trodden paths through fertile areas, these birds choose to scale mountains and cross deserts,” said Delmore.

The dangerous routes probably cause more hybrids to die on migration than their pure counterparts, thus keeping the subspecies distinct.  Says Delmore, “The self-destructive behavior of hybrids could be helping to maintain the great diversity of songbirds we enjoy.”

Read more about this study here at Science Daily.

 

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

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Oct 14 2014

Quiz: Which Ones Are Ungulates?

Published by under Mammals,Quiz

Deer eats snow (photo from Wikimedia Commons)

While writing about elk, I wanted to use the word ungulate so I looked up how to spell it.  I learned more than I bargained for … and ultimately didn’t use the word.

Ungulates are mammals with hooves, right?  Well, some are obvious, some are not.  Here’s a quiz to test your knowledge.

Which of these animals are ungulates?

A.  Deer (photo above):

B.  Horse:
Nokota horses (photo from Wikimedia Commons)

C.  Llama
Llama (photo from Wikimedia Commons)

D. Leopard:
Leopard on a tree (photo from Wikimedia Commons)

E. Hippopotamus:
Hippopotamus (photo from Wikimedia Commons)

F. Porpoise:
Harbor porpoise (photo from Wikimedia Commons)

 

Leave a comment with your answer.

If you’re stumped, I’ll post the answer in the comments later.

Can’t wait for the answer?  Click here. No cheating!

 

p.s. See the comments for an explanation about the oddest ungulates.

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

7 responses so far

Oct 13 2014

What If…?

Published by under Musings & News

Portraits: Christopher Columbus, Passenger pigeon (images from Wikimedia Commons)

This year’s remembrance of the passenger pigeon is, for me, inextricably linked to Christopher Columbus.

Last year I read a book that generated that association.  1491: New Revelations of the Americas Before Columbus describes what North America was like before and after Columbus’ arrival.

Before Columbus, the human population in the Americas was larger than Europe’s and the landscape, animals and birds were balanced by the pressure of so many people.  Europeans arrived and accidentally left behind pigs carrying human disease.  Native Americans, who had no immunity to European disease, encountered the free-range pigs and spread the plagues through human contact.

The Western Hemisphere suddenly lost 95% of its human population in only 150 years.  Remove the keystone species and you get some pretty weird results.  European settlers didn’t see the transformation so they thought what they found was normal including the endless forest, huge bison herds and billions of passenger pigeons.

So I wonder …

If Native Americans had not died off, would passenger pigeons have boomed at all?

If there hadn’t been so many passenger pigeons, would we have hunted them to extinction?

What if?

 

(Two photos from Wikimedia Commons: portrait of Christopher Columbus by Sebastiano del Piombo, 1519.  Digital painting of the extinct Passenger Pigeon Ectopistes migratorius by Tim Hough.)

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Oct 12 2014

Not A Rose

Goldenrod gall (photo by Kate St. John)

Though shaped like a green rose this knob is not a flower. It’s a goldenrod bunch gall.

A search at BugGuide.net(*) indicates:

The gall was made by a midge, Rhopalomyia solidaginis, that lays its egg at the tip of the goldenrod stem.  “Its larva secretes a chemical that prevents the goldenrod stem from growing although it continues to produce leaves, thus a shortened bunch of leaves is formed.”(*)

The resulting rosette provides shelter for many insects as well as the midge.

This fall I’ve seen many bunch galls in goldenrod fields.  This one was at Wingfield Pines in southern Allegheny County.

Click here to read more about the midge at BugGuide.net.

 

(photo by Kate St. John)

 

2 responses so far

Oct 11 2014

Fall Color Weekend

Published by under Phenology

Fall scenery, October 2011 (photo by Steve Gosser)

This long Columbus Day weekend is a good time to get outdoors and enjoy the fall colors, especially in the forests north and east of Pittsburgh.

 

Steve Gosser photographed this beautiful scene in October 2011.

(photo by Steve Gosser)

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Oct 10 2014

Click On Every Penguin

Penguin Watch: count the penguins (image from Zooniverse Penguin Watch)

Are you hooked on penguins? Would you like to see more of them from the comfort of your home?

Check out the new online citizen science project, Penguin Watch, where you can view more than 175,000 photos of Antarctic penguins, chicks and eggs.

Because penguins are declining, scientists are monitoring them using remote cameras.  The cameras have taken a lot of pictures — so many that the task of counting the penguins and their breeding success is impossible for the few scientists involved.  That’s where citizen science comes in.

Zooniverse put the photos online and made an easy tool for counting the penguins.  Look at the photo.  Click on every penguin. Done!  The clicks become a crowd-sourced map of Antarctica’s penguins.

It doesn’t matter if you make mistakes because crowd-sourcing smooths out the errors. You can even chat about the images with other volunteers and the researchers at Penguin Watch Talk.

Help scientists understand why penguin populations are declining and how to protect them by visiting www.penguinwatch.org or these links on Facebook and Twitter.

Look at the photos.  Click on every penguin.  That’s all you have to do.

 

(remote camera photo of penguins in Antarctica from Zooniverse Penguin Watch.  How many do you see?)

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Oct 09 2014

TBT: Remembering Their Dialects

Published by under Vocalizations

Swamp Sparrow (photo by Chuck Tague)

Throw Back Thursday (TBT):

October is sparrow time in Pennsylvania. Migrating warblers have left.  Migrating sparrows have arrived.

Though swamp sparrows aren’t singing right now, the species is famous for their regional dialects.  Over the winter they’ll be exposed to other sparrows with other dialects.  Will they change their accents to match their winter friends or retain their dialects to use next spring?

How do swamp sparrows remember their songs?  The answer is in this 2008 blog post:  It’s Done With Mirrors

 

(photo of a swamp sparrow by Chuck Tague)

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Oct 08 2014

Gallinule On Steroids

Purple swamp Hen at Wollongong botanic gardens (photo by Toby Hudson)

Have you ever seen this bird?

It resembles a purple gallinule (Porphyrio martinicus) but it’s the size of a chicken with darker plumage and scary-looking feet.  It looks like a gallinule on steroids.

This is, in fact, a purple swamphen (Porphyrio porphyrio), native to Africa, tropical Asia, Indonesia, Australia and New Zealand, but you don’t have to travel that far to see one.

I learned in an ABA article by Bill Pranty that purple swamphens mysteriously appeared at the Silverlakes development in Pembroke Pines, Florida in 1996.  Some speculated that the birds had escaped from Miami MetroZoo during Hurricane Andrew four years earlier, but the zoo hadn’t lost any swamphens.  Closer inspection revealed that two breeders a quarter mile from Silverlakes had allowed their purple swamphens to roam free.  Naturally some of the swamphens didn’t come home.

By October 2006 purple swamphens were so prolific that Florida’s wildlife managers decided to eradicate them, but more than two years of shooting had no effect.  The swamphens continued to expand their range.  The failed eradication program ended in December 2008.

The first time I ever saw a purple swamphen was last December at Green Cay Wetlands in Boynton Beach, Florida, about 40 air-miles from their original release point.  I’ve birded in Palm Beach County numerous times since the swamphen’s release — especially at Wakodahatchee Wetlands where they appeared in 2000 — but it took 20 years for me to see one.

Though the bird was added to the official ABA Checklist in February 2013, their reputation is tarnished.  When I pointed out my new Life Bird to another birder standing nearby she said, “They aren’t a good thing to see.”

Read about the purple swamphen’s history, the unsuccessful attempt to eradicate them, and their expansion in Florida in this article by Bill Pranty.

 

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

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Oct 07 2014

Water Cuts Rock

Published by under Musings & News

Kiskiminetas River at Roaring Run near Apollo, PA (photo by Kate St. John)

Amazing as it seems none of the hills in the Pittsburgh Low Plateau were ever mountains.  They were all made by water cutting rock.

When dinosaurs roamed the earth, Pittsburgh was at the shore of a shallow inland sea to our west.  At the time our soil was composed of sandy beaches, mudflats and swamps. The sand became sandstone, the mud became shale, and the decayed swamp plants became coal.

No geologic events deformed our rocks.  To our east the Appalachians slammed into the edge of the plateau and pushed up the Allegheny Mountains.  To our north the retreat of the glaciers made the land rise in a bounce-back from the pressure release.  Our plateau remained essentially flat, tilting slightly to the south and west.  Indeed the rock layers in our area are horizontal.  You can see this at highway road cuts.

But Pittsburgh doesn’t look flat.

Water transformed us, cutting dendritic paths in the landscape as it drained to the inland sea (now the Gulf of Mexico). The paths became deep valleys.  When you stand in a valley you see hills.

Vegetation now hides what happened to the land. You see the hills but none of the water cuts as shown in this view of the Kiskiminetas (Kiski) River at the mouth of Roaring Run.

Take a short hike up Roaring Run and see what water can do.

Water cuts rick at Roaring Run, Armstrong County (photo by Kate St. John)

Here the creek is carving a notch in weak shale.  The valley walls are steep and narrow.  The notch is big enough to wade in.

Eventually Roaring Run may look like the Kiski with tree-covered hills.

It all comes from water cutting rock.

 

(photos by Kate St. John)

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Oct 06 2014

Locate And Protect Eagle Roosts

Published by under Birds of Prey

Bald eagle adult and two juveniles, Crooked Creek (photo by Steve Gosser)

In the winter, bald eagles are more social than your typical bird of prey.  Most raptors are paired or alone in the non-breeding season but bald eagles congregate in large numbers where food is plentiful.  Visit Conowingo Dam in November and you’ll find hundreds of eagles every day.

Eagles have to sleep somewhere so when night falls they roost together.  Sometimes a few choose a temporary location.  Often a large group roosts in the same place every year.

Roosts are so important to bald eagles’ lives that they’re protected by the Bald and Golden Eagle Protection Act which prohibits disturbing eagles in any way that “substantially interferes with their normal breeding, feeding, or sheltering behavior.”  On paper this protects their roost trees from being cut down even when the eagles aren’t there.

But the Act can’t protect a place no one knows about.  Where are the roosts?

To answer this question the Center for Conservation Biology (CCB) has been mapping bald eagle roosts in North America using their own and others’ eagle tracking data. (CCB and others have fitted eagles with satellite backpacks.)  So far they’ve located more than 1,000 roosts.  Now it’s our turn to help.

Last month CCB launched an online Eagle Roost Registry.  Click here to see a map of the 1,000 roosts.

Do you know of a roost that’s not on the map?  Contact Libby Mojica at the Center for Conservation Biology (ekmojica@wm.edu, 757- 221-1680) or visit the online registry to sign up.

Click here for more information at the Center for Conservation Biology.

 

(photo of bald eagles at Crooked Creek by Steve Gosser)

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