Archive for the 'Migration' Category

Sep 10 2012

Watch Migration On Radar

Published by under Migration

At this time of year migrating thrushes and warblers spend their days eating and resting.  Then at sunset they don’t sleep, they fly!

Most birds that flap to migrate choose to travel at night because the calmer air makes flying easier and they can see the stars by which they navigate.

From sunset until 2:00am — sometimes until sunrise — they are in the air above us flying in loose flocks kept together by contact calls.  The number of travelers peaks between 11:00pm and 1:00am on nights with a north wind.  We know this because they’re seen on radar.

Back when radar was first widely used during World War II operators noticed that many things showed up as blips on the screen including rain, snow, birds and insects.  After the war, radar came into its own as a weather forecasting tool.  Nowadays it’s easy for birders to monitor nighttime migration because weather radar is available on the Internet.

To demonstrate how birds show up on radar, Cornell University created a time-lapse video showing migration over the U.S. on the night of October 1, 2008.  Read the explanation below, then watch the video above:

“This animation created by Cornell University researchers illustrates the use of a network of surveillance weather radar to record nocturnal migrating birds, bats, and insects in the continental U.S. from sunset to sunrise Oct. 1, 2008. The blocky green, yellow, and red patterns, especially visible on the east coast, represent precipitation; but within an hour after sunset, radar picks up biological activity, as seen in the widening blue and green circles spreading from the east across the country. The birds, bats, and insects take off, fly past, and get sampled by the radar beam. Note, the black areas on the map do not represent places without birds, necessarily, but rather places where radar does not sample.”  — from

You can watch migration, too.  Tonight Pittsburgh’s wind will be from the north so you’ll see birds on the move if you tune in to the National Weather Service radar loops after sunset.  Pittsburgh appears on two maps:  Central Great Lakes and Northeast.  Click on the links and watch bird activity appear after sunset and subside at sunrise. Remember that the best time is 11:00pm to 1:00am.

For more in-depth observations and hard core science, this 10 minute tutorial by David La Puma explains how to use Nexrad images to monitor migration. La Puma used to post daily radar migration updates for New Jersey on his blog at but has taken a break from it this fall.

(video from October 1, 2008 by Cornell University via YouTube)

p.s.  Click here for Drew Weber’s analysis of last night’s activity posted on Nemesis Bird.

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Sep 06 2012

Antarctic Visitor

True confessions.  When I’m in Maine I usually go on a whale watching trip but my real goal isn’t whales, it’s pelagic birds.

I’m not the only birder on the whale watch boat.  There’s usually a dozen of us keeping our eyes peeled for gannets, shearwaters, jaegers and storm petrels.

Storm petrels are my favorites because they’re so dainty.  Only the size of starlings, they appear to walk on water as they search for food.

The most common type in the Gulf of Maine in early September is Wilson’s storm petrel, pictured above.  When I learned where they came from I was amazed.

Wilson’s breed in colonies on the coast of Antarctica.  Like most storm petrels they nest out of sight in crevices and burrows and only visit their nests under cover of darkness.  That’s how they hide their eggs and young from raiding gulls and skuas.

When not breeding they live on the open ocean and never come to the land, but they’re easy to see on a pelagic trip because they’re willing to approach boats.

So while it’s winter on the southern ocean I get to see this Antarctic visitor off the coast of Maine. Soon they’ll journey back.

(photo by Patrick Coin via Wikimedia Commons.  Click on the photo to see the original)

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Aug 27 2012

Beachy Bird

According to Birds of North America Online this slender, inconspicuous bird begins its southward migration next month.

American pipits breed in some of the harshest habitat of any songbird.  They prefer open tundra and mountaintops above treeline where bad weather is the greatest threat to their nesting success.  In a bad year, their nests suffer 80% mortality when deep springtime snow covers their eggs and young. 

In the fall they avoid the coming snow, flying south to beaches and open mudflats. I’ve seen them at the edge of Shenango Lake and on the treeless mountaintops of Acadia National Park.

I even saw several lone pipits on the beach at Cape Cod in early August. 

I don’t know why those August pipits left the tundra for the beach but it certainly wasn’t because of snow this summer!


(photo by Alan Vernon via Wikimedian Commons. Click on the photo to see the original)

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Aug 02 2012

Dark Monarchs Fly Better

Here’s something I would never have known had I not read it in Science Daily.

Did you know that the migratory generation of monarch butterflies — the ones that fly to Mexico — are darker red than the earlier, more sedentary generations?  The monarchs you’re seeing right now are less red than the ones you’ll see in late August.

You’re probably aware of this color difference if you raise and tag monarchs as Marcy Cunkelman does, but do you know why the last generation is darker?  Scientists are on the verge of finding out.

According to Science Daily and PLoS ONE:  Recent research, led by Andrew Davis of the University of Georgia, tested 121 captive monarchs in an apparatus called a tethered flight mill where they quantified butterfly flight speed, duration, and distance.  They found that monarchs with darker orange wings overall flew longer distances than those with lighter wings.  This suggested that pigment deposition during metamorphosis is linked with flight skill traits such as thorax muscle size, energy storage or metabolism.

It makes sense to me that a bug that has to fly to Mexico is born with the traits necessary to do the job, and it’s not too amazing that dark color is one of them.  In birds, dark feathers are stronger than light-colored feathers.  Perhaps this applies to the wing scales of butterflies, too.

For a picture of these color differences, see the Science Daily article here and the original article at PLoS ONE.

Meanwhile, if you have a butterfly net and a camera you can do some research on your own.  Look for monarchs now and again at the end of the month. When your photographs record darker red monarchs in late August, you’ll know why.

(photo of a monarch butterfly by Marcy Cunkelman)

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Jul 30 2012

Have You Seen Me Lately?

It’s easy to notice when a new bird arrives in town, much harder to notice when a resident leaves.  This month the new arrivals are shorebirds.  Has any nesting bird departed yet?

Here’s a tale of two breeders who may have left — or soon will leave — our area.

Baltimore orioles nested in Schenley Park this year as they always do. (I have photographic evidence.)  They arrived in late April, quickly set up shop, and fledged young by mid-June.  In July they virtually disappeared.  The last time I saw an oriole in the park was in June.  The last time I heard one was July 12.

Orioles can afford to leave their breeding grounds early because they raise only one brood per year and their young are soon independent after fledging.  Mother orioles leave the family in late June.  The fathers leave a few days later.  Sometimes the young gather in juvenile flocks in August but the adults tend to be solitary and quiet.  That’s probably why they seem to be missing.

Dickcissels are another story.  They’re so unusual in Pennsylvania that many birders know exactly when they arrived and many will notice when they leave.  Every few days there’s a new report on the presence or absence of dickcissels.

Quite soon breeding will be over and the dickcissels will form flocks to head to their wintering grounds in Venezuela.  Since they’re not in a rush they often spend August and September in the grain fields of Arkansas, Louisiana and Texas.  Notice the word “August.”   That’s only two days from now.

I expect the dickcissels will leave our grasslands soon.  Schenley Park’s orioles appear to be gone.

Have you seen either of them lately?

(Baltimore oriole photo by Steve Gosser, Dickcissel photo by Bobby Greene)

6 responses so far

Jul 26 2012

Migration Has Already Begun

It’s still summer — especially today with a forecast heat index of 100oF — but fall migration has already begun.

Shorebirds are on the move and this year we may see some rarities in land-locked western Pennsylvania because the drought has lowered water levels and exposed many mud flats.

Last Sunday Shawn Collins saw sanderlings at Tamarack Lake in Crawford County and on Tuesday five American avocets were a one-day-wonder at Yellow Creek State Park in Indiana County.

Check the edges of local lakes and you’ll likely find killdeer, sandpiper “peeps,” spotted sandpipers, solitary sandpipers, and lesser yellowlegs.  If you’re lucky you’ll find a surpise like the avocet pictured above.

And if thunderstorms or heat force you indoors, stop by Steve Gosser’s exhibit at Penn State’s New Kensington campus to see beautiful photographs of birds.

Steve’s one-man show, My Feathered Friends – Bird Portraits, runs through Friday, July 27.  This is your last chance to see it.   Click here for directions.

(photo by Steve Gosser)

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May 04 2012

Crowds of Warblers

When I saw a hooded warbler in Schenley Park Tuesday morning I knew it was time…

The warblers are here!

Tuesday’s birds were just the leading edge of a huge, singing wave of tiny, colorful birds heading north to breed.

Many warbler species are just passing through.  We see them for a week or two and then they’re gone.  In the fall they pass through again heading south, but then they’re silent and dull looking.

So there’s no time to waste.  I’m dropping everything and heading for Magee Marsh in northwestern Ohio where I know the warblers are easy to see and very plentiful.  I’ll be there for part of The Biggest Week in American Birding and so will thousands of others. It’s a crowd scene of birds and birders.

If you’re thinking of birding Magee Marsh there’s still time. The warblers will be going strong through mid-May.

This weekend I plan on seeing a prothonotary warbler.  That’s where Bob Greene photographed this one.

(photo by Bobby Greene)

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May 02 2012

South Wind

Songbirds migrate at night and they like to have a tail wind so this week’s weather has been great for moving north.

Before dawn on Monday the wind swung around to the south. That morning I saw my first Baltimore oriole of the year and heard a red-eyed vireo in Schenley Park.

Yesterday I saw a chestnut-sided warbler, a hooded warbler (pictured above), white-throated sparrows and many rose-breasted grosbeaks.

Despite the rain I bet it will be another good day for birds.

I wonder who arrived last night on the warm wind.

(photo of a hooded warbler at Sewickley Heights Park, April 28, by Shawn Collins)

7 responses so far

Apr 19 2012

Mass Migration

Last Friday I took the day off and visited Presque Isle State Park.  It felt like a mini beach vacation to walk along the shore of Lake Erie and pretend I was at the ocean.

With the waves lapping at my feet I paused to gaze north.  I knew that Long Point, Canada was more than 25 miles away but it was beyond the horizon, invisible.

Suddenly I noticed that butterfly after butterfly flew from behind me and headed straight out over the open water.  They were brown, orange and white and they flew very fast, zigzagging on their way.

What was this steady stream of butterflies?  Red admirals.

Red admirals (Vanessa atalanta) live in temperate Europe, Asia and North America.  They cannot survive winter’s cold so they migrate south in the fall.  In the U.S. Red Admirals overwinter in south Texas.  In March they start their journey north.

How long would it take for these delicate creatures to cross Lake Erie?  I estimated I would have to run to keep up with them so I guessed they were traveling 7 miles per hour.  If they flew due north they’d reach Long Point in 3.5 hours, but they were headed northeast, a trip of 50 miles to the mainland of Canada.  This long route would take them more than seven hours.  It was 3:00pm.  They would arrive at night.

What I saw was only the beginning.  By Sunday the south winds and warm temperatures had triggered a mass migration.  From the Presque Isle Hawk Watch, Jerry McWilliams reported to PABIRDS:

“Probably the most remarkable observation was the mass movement of Red Admirals (Vanessa atalanta) flying SW to NE. A conservative estimate of the butterflies moving past the watch was 25 individuals per minute making the total estimate of the count around 5500 butterflies!”


The photo above matches what I saw.  The fall brood of Red Admirals is brown like this.  Those hatched in spring/summer are blacker.

(photo by Daniel Herms, The Ohio State University,

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Apr 13 2012

Why Birds Get Here Last

Published by under Migration


Earlier this week Libby Strizzi sent me an email with this ruby-throated hummingbird migration map and the question:  Why are the hummingbirds everywhere but here?

The map from is shown above with a black circle I drew to highlight the absence of hummers.  Hummingbirds have been seen east, west and north of northwestern Pennsylvania but not in the “hole.”

I’ll bet this is because northwestern PA is not on any spring migration flyways.

Migrating birds use four aerial “highways” to reach their breeding grounds in the spring.  Pennsylvania is fed by the Atlantic Flyway.  You can see this on the map below by Melissa Mayntz, linked from


Notice the “hole” in northwestern Pennsylvania where the migration highway splits into two streams.  Early migrants are probably following the main highway and not stopping in PA’s northwest corner.  Other migrants fill in the gap but they arrive later.

And notice that two flyways meet in northwestern Ohio at Lake Erie.  Two sources of birds!  That’s why birders flock to Magee Marsh, Ohio in May.

We’ll just have to be patient.  They’ll get here when they get here.

(Hummingbird map from  Flyways map by Melissa Mayntz, linked from  Click on each map to see the original in context.)

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