Archive for the 'Migration' Category

Sep 26 2013

Thousands Of Blue Jays

Published by under Migration

Blue jay (photo by Charlie Hickey)

There are times when I ask myself, “Where have the blue jays gone?” but this is not one of them.  They’re everywhere right now.

I think of blue jays as year-round residents — and they are through most of their range — but a good number of them migrate.  Their travels, however, are poorly understood because they’re unpredictable.

Some blue jays stay, others go.  Those who leave may be young or old (not just juveniles) and an individual who stayed last winter might leave this year and not the next.  Some don’t bother to come “home” in the spring and are found nesting further south. Others come home to nest but go further south each winter.  The only hint is that blue jays store and eat acorns in the winter so the mast crop may influence their decision to travel.

Blue jays migrate during the day in loose flocks of 10 to 30 birds that often pass by hawk watches. At Cape May, New Jersey, 1,000 to 5,000 blue jays pass by each day from late September through early October.  For the really huge numbers visit Holiday Beach Migration Observatory in Amherstburg, Ontario, 23 miles south of Detroit.

Because jays are reluctant to fly over Lake Erie, they hug the northern shore and funnel past Holiday Beach as they travel southward out of Canada. Typical days in late September and early October see 30,000 to 40,000 blue jays fly by.  The highest count was 264,410 on September 28, 2001.  Observers must have wondered if any blue jays were left in Canada after a day like that!

We never see numbers like this in Pennsylvania though we get a bump up in spring and fall.  Here’s a quick visual from eBird of blue jay population fluctuation in Pennsylvania, years 2009-2013.  Click on the image to see the real graph.

Frequency of Blue Jays in PA, 2009-2013 as of 9/24/2013 (screenshot from eBird)

 

The low point for blue jays in Pennsylvania is late December to early March.

Remind me of this when I ask you where the blue jays are this winter.

(photo by Charlie Hickey. Click on the image to see the original.)

 

p.s. Here are the blue jay record-setting dates from Holiday Beach, Migration Observatory.  Click here for all non-hawk species counts.
Blue Jay Record High Counts:
Sep 26: 1986 = 49,280,  1991 = 59,650
Sep 28: 2001 = 264,410*
Sep 30: 1990 = 51,470, 1993 = 87,000
Oct 1: 2009 = 158,300
Oct 5: 2009 = 152,750

3 responses so far

Sep 25 2013

The Sun Compass

Male monarch butterfly (photo by Marcy Cunkelman)

A week ago I saw my first and only monarch butterfly of 2013.  Their sudden disappearance is both troubling and saddening.  It’s now possible to imagine a world without monarch butterflies.  We are nearly there.

Last winter’s monarch survey in Mexico showed their population was down 59%, a record low.  There have always been population fluctuations but the trend has been running low and lower since 2004.  Scientists believe that agricultural pesticides and herbicides have reduced available poison-free habitat for butterflies (similar to the bees’ problem), so this spring monarch enthusiasts encouraged people to grow safe-haven milkweed for the butterflies.  It wasn’t enough.

Each species has an intrinsic value.  If, or when, the eastern monarch butterfly goes extinct we will lose its pollination contribution, milkweed symbiosis, beauty, and the amazing adaptations that allow multiple generations to migrate from Mexico to Canada and back.

One of the adaptations that will disappear is this:  Monarch butterflies have a sun compass in their antennae.

Their antennae have light sensors that track the amount of light each day.  According to a study in 2009 by Merlin, Gegear and Reppert, this circadian clock “provides the internal timing device that allows the butterflies to correct their flight orientation, relative to skylight parameters, and maintain a southerly flight bearing, as the sun moves across the sky during the day.”  Migratory monarchs without antennae fly in aimless directions.  Monarchs with antennae always orient southwest.

The monarch’s sun compass was discovered only a few years ago.  Now there are almost no monarch butterflies to study.  The world will be a poorer place without them.

Click here for more information on the monarch’s amazing sun compass.

(photo by Marcy Cunkelman, 2008)

21 responses so far

Sep 24 2013

Longest Migration

While songbirds, hawks, and dragonflies are migrating this month there’s a bird whose journey beats them all.

The arctic tern sets long distance records in its pole-to-pole round-trip migration of 44,000 miles (71,000 km).  Since arctic terns can live 30 years, an individual can rack up a lifetime achievement of 1.5 million miles (2.4 million km).

The data behind this amazing feat was published in 2010 by the Arctic Tern Migration Project which studied arctic terns that nest in Greenland and winter in Antarctica.

To track the terns the scientists used tiny geolocator tags from the British Antarctic Survey, the same tags used to track wood thrushes.  In both studies scientists captured each bird, affixed a tag, then had to find the same bird on its breeding grounds a year later and recapture it to gather the data.  Wood thrushes don’t put up a fight but arctic terns relentlessly dive bomb their enemies to drive them away.  This study had bird hazards.

Attacking terns were not the only hazards.  Camping on an island off the coast of Greenland is no picnic.  “Our tents blew out to sea in the storm.”  Yow!

Watch this video from the Encyclopedia of Life to see the terns’ amazing migration and why it’s worthwhile for these birds to travel so far.

 

For more information, visit the Arctic Tern Migration Project at www.arctictern.info.

(video by the Encyclopedia of Life)

No responses yet

Sep 12 2013

No Food, No Water

Mount Desert Rock (photo by krzdweasel, Creative Commons license)

Twenty miles off the coast of Mount Desert Island is a tiny granite outcrop called Mount Desert Rock.  On a clear day you can see it with binoculars from the mountains of Acadia National Park. It looks like an improbable ship, taller than it is long.

Only 3.5 acres in size, Mount Desert Rock holds three buildings and a lighthouse just 17 feet above sea level. During winter storms and hurricanes the ocean washes over the island and punishes the buildings. The boathouse was swept away during Hurricane Bill in 2009. Isolated and exposed the Rock stands alone. Click here to see how small it is.

Map showing location of Mount Desert Rock (image from Wikimedia Commons)

Whale watching tours from Bar Harbor sometimes circle the Rock.  That’s how I’ve come close but never landed.  The Rock has no harbor so even those authorized to land can only do so when the sea is calm.

Lighthouse keepers and their families used to live year-round on the island, sheltering in the lighthouse during storms.  Since 1998 the College of the Atlantic has had whale and seal study crews posted there on temporary assignment, but they leave before a storm.

No matter who is stationed there, they must survive on food and water shipped from the mainland.  Rainwater is collected in a cistern under the keepers’ house but it’s undrinkable.  Nothing can grow there because the ocean washes away the topsoil in every storm.  And there is noise: The foghorn blares every 30 seconds.

When the weather is right, songbirds take a shortcut across the Gulf of Maine during fall migration from Nova Scotia to Maine.  From the whale watch boat I’ve seen ruby-throated hummingbirds and robins pumping their way past the Rock to Mt. Desert Island 20 miles away.  It’s scary to think they are over open water, sometimes fighting the wind, spending themselves to make landfall on the shores of Acadia — or else they will die.

Fly safe, little birds.  The Rock is no place to rest.  No food.  No water.

(photo by “krzdweasel” via Flickr, Creative Commons license.  Click on the image to see the original. Map from Wikipedia.)

2 responses so far

Sep 11 2013

On The Move

Published by under Migration,Songbirds

Swainson's thrush (photo by Shawn Collins)

Last night in Bath, Maine I heard thrushes migrating in the dark.  As they fly they make short contact calls to keep the flock together. Among the calls, I was able to identify two species.

The first call was plentiful and sounded like the single note of a spring peeper.  Those were Swainson’s thrushes (above).  Click here to hear the peep sound at the beginning of the recording.

The second sound was less frequent.  There were fewer of this species, their call note lasted longer and descended roughly.  By listening at the Macaulay Library online I determined they were gray-cheeked thrushes (below).  Click here to hear.

Gray-cheeked thrush (photo by Shawn Collins)

 

Last night the birds were on the move while the weather was good.  Today will be hot.  Tonight will be stormy.

 

(photos by Shawn Collins)

No responses yet

Aug 19 2013

Western Hummer Season

Published by under Migration,Quiz

Mystery Hummingbird #1 (photo by Steve Valasek)

Last week Scott Weidensaul reminded Pennsylvania birders that with hummingbird migration underway we might — just might — see a rarity at our feeders.

He wrote, “PABIRDers will recall that last fall and winter we documented an astounding 94 western hummingbirds of four species in Pennsylvania, and that was probably the tip of the iceberg.”

In honor of Western Hummer Season I’ve made a quiz with a twist. These recent hummingbird photos were all taken outside of Pennsylvania by former Pittsburghers.  Some of these birds can be found in Pennsylvania, one cannot, and one of Pennsylvania’s rarities isn’t pictured here at all.

Can you identify these hummingbirds?  (starting with Mystery #1 above)

Experts will know what they are.  The rest of us can appreciate the beautiful photos.  Don’t feel bad if you can’t identify them — I couldn’t without looking them up.   Answers are in the first Comment.

Mystery Hummingbird #2:
Mystery Hummingbird #2 (photo by Steve Valasek)

 

Mystery Hummingbird #3:
Mystery Hummingbird #3 (photo by Steve Vlasek)

 

Mystery Hummingbird #4:
Mystery Hummingbird #4 (photo by Steve Valasek)

 

Mystery Hummingbird #5:
Mystery Hummingbird #5 (photo by Chuck Tague)

 

Keep your hummingbird feeders full and watch for unusual birds this fall.  The hint may be just a slight color difference.

After October 15, any hummer you see in Pennsylvania is a western rarity to report on PABIRDS or to Bob Mulvihill at the National Aviary (412.323.7235).

 

(all photos by Steve Valasek, except for the photo with a flower which is by Chuck Tague)

p.s.  See Rob Protz’ comment for the western hummer species I forgot to mention…

8 responses so far

Aug 03 2013

Visiting Shorebirds

Marbled godwit at Conneaut Harbor, Ohio (photo by Steve Gosser)

Shorebirds are migrating but we’re not likely to see them in Pittsburgh because we don’t have a shore. However there’s an excellent place north of us that does:  the harbor at Conneaut, Ohio.

Conneaut’s harbor was formed where Conneaut Creek flows into Lake Erie.  The lake’s waves can be rough so the harbor has been sheltered by two breakwaters.  These allowed the creek (and probably the harbor dredge) to deposit a sand spit and mud flat so extensive you can park on it.

Visiting shorebirds feed at the water’s edge and rest on the sand.  Sometimes they’re so close you have to back up to see them with binoculars!

The harbor is more than two hours away but the trip is well worth it.  Steve Gosser photographed this marbled godwit there in July.

Click here for a map and the harbor’s eBird checklist.  The best place is called the “sand spit” on the map.

More shorebirds coming.  Visit them at Conneaut.

(photo by Steve Gosser)

One response so far

Jun 26 2013

I’m On A Tight Schedule

Published by under Migration,Peregrines

Island Girl, 2009 (photo by Bud Anderson from the Southern Cross Research Project)

Late June is an intensely busy time for peregrine parents in North America’s mid latitudes. If their nests were successful they have young about to fledge or already on the wing who must become independent in just four to eight weeks.

If you think that’s fast, consider the life of an arctic peregrine.

Island Girl, pictured above, is an arctic peregrine tagged with a satellite transmitter in southern Chile in 2009 by the Falcon Research Group. They’ve tracked her migrations every year in amazing detail, able to determine latitude, longitude and altitude of her roosts and see the neighborhood where she chooses to sleep via Google Earth.

Island Girl nests on Baffin Island, Canada and spends November to April on the coast of southern Chile. To do this she travels nearly 17,000 miles per year.  This spring she left Chile on April 17 and arrived at her eyrie in Canada on June 3, covering 8,868 miles in only 48 days. She got home early.

Here’s a screenshot of her trip.  (Click on it to see the real map.)  This is the feat of an athlete!
Screen shot of Island Girl's migration tracking map, Spring 2013 (from Southern Cross Peregrine Project)

Now that she’s on her breeding grounds Island Girl has a very compressed schedule. She arrived on June 3 (the day Silver Boy fledged) and absolutely must leave in late September.  Winter comes quickly on Baffin Island so Island Girl always leaves between September 20 and 24.  Always.

This gives her about 111 days to court, lay eggs, incubate, raise nestlings, and teach fledglings.

Her schedule probably looks like this:

  • Courtship and egg laying:  14-18 days, June 3 to June 19.  This is the most optimistic schedule, assuming an established mate, an established territory and no intruders.
  • Incubation: 33-35 days, June 19 to July 23
  • Nestling phase, 39 to 45 days, July 23 to September 3
  • Fledged young dependent on parents, 4-8 weeks,  September 3 to October 1 or October 29.

There’s barely time to fledge young and begin to teach them before she has to leave for Chile. In fact her kids might leave with her and learn to hunt while traveling.

Arctic peregrines are certainly on a tight schedule!

 

(Island Girl photo by Bud Anderson and Spring 2013 migration tracking map from the Southern Cross Peregrine Project, Falcon Research Group Click on the images to see the originals)

3 responses so far

May 16 2013

A Two Week Trip

Wood Thrush (photo by Steve Gosser)

I heard my first wood thrush this year in Schenley Park on April 24 but the real influx didn’t occur until May 8.  On that morning the wood thrush population in the park doubled overnight.

Each bird made the trip from eastern Honduras or Nicaragua in 13-15 days.  We know where they spend the winter, how long it takes to get here, and the routes individual birds take thanks to ongoing migration studies by Bridget Stutchbury’s University of York team, begun in 2007.

Stutchbury pioneered the use of tiny geolocators, smaller than a penny, that record only two things: the universal date-time (UTC) and the amount of light.  Crunch a year of data and you get sunrise, sunset and day length which reveal the bird’s location each day.  To collect this data, the tagged bird had to return from migration (a 60% chance) and be re-trapped to remove the geolocator (90% success rate, skill required!).

Now that the team has tracked some individual wood thrushes for several years they’ve found that:

  • Wood thrushes fly more than 300 miles a day on migration.
  • In the fall, they may stopover in the southern U.S. or the Yucatan for one to four weeks before proceeding to their final destination.
  • They dawdle in the fall but return two to six times faster in the spring because they barely stop at all.
  • Wood thrushes who live near each other in Pennsylvania don’t scatter when they get to Central America.  A single breeding population from Pennsylvania spends the winter in a narrow band of forest in eastern Honduras and Nicaragua.  If that forest disappears, so will all those wood thrushes.
  • Wood thrushes don’t use local weather cues to determine when to head north.  Instead they have built in endogenous triggers similar to long-distance shorebirds.  Some of their triggers are so accurate that individuals begin northward migration on the same day every year.
  • Though wood thrushes tend to have a favorite departure date they don’t take the same route every year.  The route depends on weather and fitness.
  • First year birds tend to leave the wintering grounds later than those who’ve made the trip before.

So I’ll bet those early wood thrushes are the older, experienced birds who left Central America around April 10.  Two weeks and more than 2,000 miles later they arrived in my neighborhood on the day the rest of the flock left the wintering grounds.

Awesome!

 

For more on these studies, click here for background on the 2010 report and here for their 2012 findings.

(photo by Steve Gosser)

One response so far

May 07 2013

Important Rest Stops

Published by under Migration

Bay-breasted Warbler (photo by Chuck Tague)

Birders flock to Magee Marsh, Ohio in May because the birds do, too.  For us it’s exciting to see them so close. For them it’s an important rest stop on their long journey from Central or South America to Canada.

Songbirds migrate overnight and stop before dawn to rest for the day. They may be leisurely in the fall but they make the journey faster in spring.  This bay-breasted warbler travels from Panama or northern South America to Canada, a journey of at least 2,400 miles, and he does it in as little as 17 days.  His longest leg is more than 500 miles non-stop across the Gulf of Mexico.

Rest stops are key.

Imagine you’re driving each night on a long distance journey.  From experience, or because you’re traveling in a group (i.e. flock), you’ve picked the rest stops in advance.  You’re on a tight schedule and you’re not going to stop often.  A few of the rest stops are the last food and fuel for hundreds of miles.  No problem.  You’ve been there before and you know those places are good.

But what if you arrive one night and a crucial rest stop is gone… destroyed?  No gasoline, no food and you’re nearly out of both.   You have no idea where to find a substitute and you’re already tired.  If you’re a bird, this emergency can kill you.

That’s why the warblers at Magee Marsh don’t seem to care about people. They’re hungry and they don’t have much time.  They’re fueling up so they can leave tonight for Canada.

And that’s why the National Audubon Society, the American Bird Conservancy, the Nature Conservancy, and the Western Hemisphere Shorebird Reserve Network  are all working to preserve stopover sites for migratory birds.

 

(photo by Chuck Tague)

One response so far

« Prev - Next »

Bird Stories from OnQ