Archive for the 'Migration' Category

Feb 23 2015

Across The Sahara

Eleanora falcon with satellite tracking backpack (photo by Pacual López/ SINC via Science Daily)

When you know a bird’s winter and summer homes, can you guess the route it takes on migration?  Not necessarily.

Eleonora’s falcon (Falco eleonorae) spends the summer on islands in the Mediterranean and winters at Madagascar.  How does it travel from Europe to that big island east of Africa?  For decades ornithologists assumed it followed the coast — the Mediterranean Sea to the Red Sea to the Indian Ocean.

The assumption makes sense because in Europe Eleonora’s falcons eat small birds that they capture in the air over the sea.  Of course this falcon would take a water route … until a 2009 tracking study proved it wrong.

From 2007 to 2009, researchers from the Universities of Valencia and Alicante satellite tagged and tracked 16 Eleanora falcons on the Balearic and Columbretes Islands off the coast of Spain.  The data showed the falcons indeed spent the winter on Madagascar but they didn’t take the long, dog-leg coastal route to get there.

If you draw a straight line from the western Mediterranean to Madagascar it crosses 6,000 miles (more than 9,500 km) of the African continent.  That’s what the falcons did.  Flying both day and night they even crossed the Sahara.

Perhaps they were eating insects as they flew.  That’s what they do in Madagascar.

Read more here at EurekAlert.

 

(photo of satellite tagged Eleonor’as falcon by Pacual López/ SINC via EurekAlert)

 

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Jan 28 2015

Incredible Site Fidelity

Published by under Migration,Travel

Whimbrel ready for release in migration tracking study (photo by Barry Truitt, courtesy Center for Conservation Biology via William&Mary news)

Whimbrel ready about to be released for migration tracking study (photo by Barry Truitt, courtesy the Center for Conservation Biology)

The U.S. Virgin Islands are so beautiful it’s no wonder people come here every winter, year after year.  Some birds do too, and they show incredible site fidelity even in their choice of rest stops along the way.

Whimbrels are large shorebirds with long decurved bills who breed on the marshy tundra of Alaska, Northwest Canada and Hudson Bay.(*)  Their breeding season is short so they make 14,000 mile annual migrations to spend most of the year in Brazil or the Caribbean.  On migration they often use the same favored stopovers on the U.S. coast.  That’s how one particular whimbrel nicknamed Hope encountered biologists from William & Mary’s Center for Conservation Biology (CCB) in May 2009.

Since 2007 CCB had been tracking shorebird migration by fitting whimbrels with satellite backpacks at their staging areas on the Delmarva peninsula.  The satellite data, mapped by CCB and The Nature Conservancy, provided astonishing results.  For instance, from 2009 to 2011 Hope traveled faithfully from the Mackenzie River Delta to Great Pond at St.Croix, nearly always stopping at Delmarva along the way.

Migration journeys of Hope the Whimbrel, 2009 to 2011 (map from Center for Conservation Biology and The Nature Conservancy, courtesy Center for Conservation Biology)

Migration journeys of Hope the Whimbrel, 2009 to 2011 (map courtesy of the Center for Conservation Biology)

Her amazing migration made news at Audubon Magazine and EarthSky.org, and became a conservation story in the U.S. Virgin Islands.

In 2012 shortly after returning to St. Croix, Hope’s satellite antenna broke, rendering the tracking unit useless.  Rather than replace the unit, CCB decided to remove it and put colorful tags on her legs so that local birders could recognize her.  Here, Fletcher Smith holds her one last time before releasing her at Great Pond.

Fletcher Smith about to release Hope in St. Croix after removing her damaged satellite backpack, 2012 (photo courtesy the Center for Conservation Biology)

Fletcher Smith about to release Hope in St. Croix after removing her damaged satellite backpack, 2012 (photo courtesy of the Center for Conservation Biology)

 

Hope retired from the tracking program but she didn’t stop her normal life.  True to her habits, she still makes her faithful journey. In August 2013 she was photographed at St. Croix having completed her first round trip to Canada without the backpack.  Here she is sporting her yellow and green leg tags at Great Pond.  She’s there this winter, too.

Hope returns to Great Pond at St. Croix, U.S. Virgin Islands, August 2013 (photo from the Center for Conservation Biology)

Hope returns to Great Pond at St. Croix, August 2013 (photo courtesy of the Center for Conservation Biology)

We humans may visit the same places every year but for truly incredible site fidelity follow a whimbrel.

Read more about CCB’s Center for Conservation Biology shorebird tracking program and watch cool videos of the Mackenzie Delta and a whimbrel with chick here at the Center for Conservation Biology.

 

(photos and map courtesy of the Center for Conservation Biology)

And … two more messages:

1. Though I visited St. John, U.S. Virgin Islands I did not go to St. Croix to see “Hope.”  St. Croix is 43 miles south of St. John and there is no longer any ferry service. Like a whimbrel, you have to fly.

2. (*) These breeding and migration ranges refer to the Atlantic-migration whimbrels of North America.  Whimbrels have a worldwide distribution.

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Nov 15 2014

Swans On The Move

Tundra swan flock in migration (photo by Steve Gosser)

Tundra swans are migrating now over western Pennsylvania.  They’re traveling 3,600 miles from Canada’s Northwest Territory and Alaska’s North Slope to Chesapeake Bay and eastern North Carolina.

Steve Gosser photographed this flock on November 12.  I saw 60 at Moraine State Park on November 13.

The flocks are composed of families: mother, father and one or two youngsters.  In the fall their trip takes about 12 weeks, a slower pace than their springtime return because their “kids” are young and need to rest longer.

Sometimes they’re hard to see.  On an overcast day they’re white birds in a white sky so listen for their voices and look up.

Do you know their call?  Click here to hear.  Start the player at the 6:00 minute mark to hear a flock approach and land at Pungo Lake, North Carolina.

Tundra swans are on the move.

 

(photo by Steve Gosser)

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Nov 03 2014

Siskin Surge

Published by under Migration,Songbirds

Pine sisken (photo by Shawn Collins)

Ron Pittaway’s Winter Finch Forecast predicted pine siskins would move south this winter but no one expected the numbers seen in eastern Pennsylvania in the third week of October.

Hawk Mountain Sanctuary counted about 3,000 per day for several days, including 3,147 on October 23.  Andy Markel and Bill Oyler counted 739 heading southwest in Horse Valley, Franklin County on October 25.

Numbers were lower in western Pennsylvania where the largest count mentioned on PABIRDS was 50 on October 20 in Allegheny County.

Interestingly, Pittaway’s forecast accounts for this.  In his assessment of northern tree seed crops (i.e. finch food) he wrote:  “Spruce cone crops are variable in Ontario … East of Ontario cone crops are generally poor in the Atlantic Provinces, New York State, New Hampshire and other northern New England States.”  That means that pine siskins northeast of the Appalachians would certainly move through Pennsylvania while those directly north of Pittsburgh might find a good seed crop and not bother to fly this far south.

Though they’re still being reported in Pennsylvania the numbers are more normal now in random flocks of 15 to 20 — at least on PABIRDS.

Where will that surge of siskins end up?  West Virginia?  The Great Smoky Mountains (where it snowed already)?  It’s probably too soon to tell.

 

(photo by Shawn Collins, Crawford County, 2 November 2014)

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Oct 18 2014

Lots Of Robins

Published by under Migration

Flock of American rovins on the grass (photo by Marcy Cunkelman)

Have you tried counting robins lately?  This week it’s been a challenge.

Though it may seem pointless I usually count birds when I’m outdoors.  The reward comes later when I look back at the numbers.

Based on my counts I know that a first wave of migrating American robins came through Pittsburgh in September.  Their numbers dropped, but a second wave arrived last week to feast on the fruit in the city’s trees and bushes.

Unfortunately these birds are camouflaged by the autumn foliage.  Rust-and-brown robins match rust-and-brown leaves.  On walks in Brookline, Oakland and Squirrel Hill I counted 20, 50, 100 robins.  Why the round numbers?  I don’t know exactly how many there were.

All I know for sure is:  There are lots of robins right now.

 

(photo by Marcy Cunkleman)

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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 01 2014

The Blue Jay Forecast

Published by under Migration,Songbirds

Blue Jay (photo by Steve Gosser)

When folks wonder why blue jays are scarce they turn to the Internet and find my 2012 blog post “Have You Seen Any Blue Jays Lately?”   In the past two+ years 116 readers have commented on the status of blue jays where they live.

The most recent comments are on the absence of jays:  Where have they gone?  Why did they leave?  When will they come back … if at all?

Over the winter blue jays eat acorns, beechnuts, hazelnuts, hickory nuts and other mast (nuts).  Their range map looks as if they never migrate but they will leave if nuts are scarce.

How can we know if the blue jays will leave? Check the Blue Jay Forecast.

Every fall Ron Pittaway produces a Winter Finch Forecast for Canada based on the abundance of tree seeds in Canada’s forests.  The finches in his report eat a wide variety of seeds including spruce, fir, birch and mountain ash.  If food is abundant the birds stay home all winter.  In poor mast years they irrupt southward.  Here in Pennsylvania we wait for Pittaway’s forecast to tell us which species will visit us in coming months.

Blue jays depend on tree nuts too and they often move when the finches do, so Pittaway includes them in his forecast.  This year he says “Expect a good to heavy flight (many more than last year) moving westward along the north shorelines of Lakes Ontario and Erie because the acorn, beechnut, hazelnut and soft mast crops averaged low in northeastern, central and eastern Ontario.”

If you live in Ontario, don’t expect to see a lot of blue jays this winter.  Lots of them are in Pittsburgh — at least right now.  Guess where they came from.   ;)

Click here for Ron Pittaway’s Winter Finch Forecast.   Scroll down to read about blue jays.

 

(photo by Steve Gosser)

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Sep 29 2014

Follow An Arctic Peregrine On Migration

Published by under Migration,Peregrines

Arctic peregrine, Island Girl (photo from the Southern Cross Peregrine Project)

Since 2007 the Falcon Research Group’s Southern Cross Peregrine Project (SCPP) has satellite-tracked some of the longest migrating peregrines in the Western Hemisphere.  Tagged at their wintering grounds on the coast of Chile, these peregrines have shown amazing stamina as they travel back and forth from Chile’s coast to the tundra cliffs of northern Canada.

Over the years the project has tracked 13 birds but now only “Island Girl,” pictured above, has a working transmitter.  First tagged in 2009 she’s provided many years of data.

In the screenshot below SCPP mapped her 2009-2013 north and south migrations.  As you can see she changes her route a bit year to year and season to season.  Heading south (red) she prefers to fly the shortest route to Chile, often across the Gulf of Mexico.  On her way north (blue) she travels by land and arcs across central Canada.  Click on the screenshot to see Island Girl’s combined 5-year map and explore her routes.

5-year map of arctic peregrine -- Island Girl -- migration routes (map from Southern Cross Peregrine Project)

Winter comes early to the Arctic so Island Girl began her southward journey this month, leaving her Baffin Island home on September 17.  By the time she roosted last night she’d already traveled 1,478 miles and was spotted by satellite at Vandeleur, Ontario just west of Eugenia Lake.

Where will she go today?

Click here for Island Girl’s Tracking Page, then drill into a date on the right to see her latest location.  Zoom the map to see the data points or click here for detailed location maps.

Follow an arctic peregrine as she migrates over North America on her way to Chile.  Go, Island Girl!

 

(photo and map from the Falcon Research Group’s Southern Cross Peregrine Peregrine Project.  Click on the images to see the originals)

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Sep 24 2014

Local And Vocal

Carolina chickadee (photo by Cris Hamilton)

Chickadees don’t migrate(*) but they’re a big help when you’re looking for migrating songbirds in late September.

Waves of warblers are still passing through Pennsylvania but they’re usually silent and hidden by leaves so you probably won’t see them … unless you listen for chickadees.

Black-capped and Carolina chickadees are vocal experts on the local scene.  They know the best places to find food and where the predators lurk.  And they’re such chatterboxes!  Visiting migrants clue into chickadee locations and often stay with them in mixed flocks.

At this time of year don’t ignore the local, vocal birds.  They may have visitors with them.

 

(photo by Cris Hamilton)

(* Well, I’ve since heard that some chickadees do go places … but others stay behind.)

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Sep 23 2014

Orange Or Yellow?

Published by under Migration

Orange-crowned warbler (photo by Dan Arndt)

Orange-crowned warbler (photo by Dan Arndt)

In good light with a clear view these two warblers don’t look alike.

Female yellow warbler (photo by Dan Arndt)

Female yellow warbler (photo by Dan Arndt)

But in poor light and partially hidden by leaves a fast-moving yellowish fall warbler without wing bars can be … confusing.

Last Sunday one of these birds had me stumped.  Without a camera to take its picture, how could I find out what it was?

Using a technique I learned from Chuck Tague, I wrote down what I saw as if I was going to draw the bird.

“Long, all-yellowish warbler with blank face, round head, blunt beak, no wing bars, no stripes.”  (Wish I’d seen the tail and leg colors.)

With this note and several field guides I was able to figure it out at home.

“No wing bars, no stripes” narrowed the field considerably.

By “all-yellowish” I meant pale yellow from throat to undertail with drabber, darker yellow on back, wings, head.  The light made the bird look very drab.  Lots of book-searching finally pointed to two possibilities:  an orange-crowned warbler or a female yellow warbler.  Range maps indicate both can occur now in western Pennsylvania so I had two viable candidates.

“Long” and “round head” can be deceiving because a squat, no-neck warbler might stretch out its neck to see me but together they lean toward yellow warbler.

“Blank face” is an excellent hint, not just a patternless face but actually flat looking.  The orange-crowned warbler has tiny white accents above and below its eyes that give its face topography even if you don’t see the accents.  Yellow warblers are known for their plain blank faces.

“Blunt beak” describes the yellow warbler’s stout bill rather than the orange-crowned’s sharply pointed bill.

So what did I see? Most likely a yellow warbler.

Oh well.  An orange-crowned would have been nice.

The key is:  Write everything down.  Pretend you’re going to draw the bird when you get home.

 

(photos by Dan Arndt, Creative Commons license on Flickr.  Click on the images to see the originals.  Dan lives in Calgary and writes for two blogs: Birds Calgary and Bird Canada.)

p.s.  I used the The Warbler Guide by Tom Stephenson and Scott Whittle to figure this out.  It’s excellent for deciphering confusing fall warblers.

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