Archive for the 'Water and Shore' Category

Oct 10 2013

Peregrines As A Fitness Program

Peregrine falcon at Lake Erie, Presque Isle, PA (photo by Steve Gosser)

Here’s my favorite bird patrolling Lake Erie’s shore at Presque Isle State Park, looking for a meal.

And here’s a potential food source — a flock of dunlin.

Dunlin at Lake Erie, Presque Isle, PA (photo by Steve Gosser)

The peregrine is looking for a bird that’s easy to catch.  The dunlin are sitting ducks (er… dunlin) if they stay on the ground so they fly and flock as soon as they see a peregrine.  This interaction has made dunlin more fit in the years since the peregrine population has recovered from the DDT crash.

A 2009 study at the Fraser River delta on the Pacific coast backs this up.  Peregrines never went extinct on the West Coast but they were very scarce in the 1970′s.  During this period wintering flocks of dunlin safely roosted on the sand at high tide and became fat — and a bit slower — in early winter.

The peregrine population began to recover in the 1990′s and soon found tasty dunlin meals as they migrated past the Fraser River delta in fall and spring. The dunlin quickly learned it was unsafe to roost at high tide during the day because peregrines were on patrol.  Instead they began to spend high tide flocking over the open ocean, flying and flying for three to five hours.  With this exertion they became much more fit and are now are measurably thinner in early winter, the time when peregrines are passing by.

Peregrine falcons have provided dunlin with a fitness program.  Be fit or be eaten.

Click here to read more about the Fraser River dunlin study.

 

(photos by Steve Gosser)

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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)

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Sep 20 2013

What’s All the Shouting About?

On vacation in Maine I saw a lot of gulls flying, posturing, and calling.

What was all the shouting about?

This video, filmed at Appledore Island, explains it all.

I wish I’d known this two weeks ago.  ;)

(video from Cornell Lab of Ornithology, featured in their September 2013 eNewsletter)

 

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Sep 16 2013

Little Blues

Published by under Water and Shore

Little blue heron (photo by Shawn Collins)

Just when you thought you’d mastered white wading birds, a wildcard shows up!

It’s the time of year for white little blue herons.  I was reminded of this when I visited Scarborough Marsh last week and encountered great egrets, snowy egrets and little blue herons, all of which were white.  Great and snowy egrets are always white, but little blues are blue … except when they’re young.

Little blue herons (Egretta caerulea) don’t breed in western Pennsylvania but juvenile birds disperse widely — they even fly north! — so it’s possible to find them outside their normal range in August and September.  Because they’re very rare in Pittsburgh I was surprised to find three at Scarborough Marsh but I should have checked the range map.  They breed in southern Maine.

With so many white wading birds how did I figure them out?  Beaks and legs!

  • Great egret:  yellow beak, black legs.  Large.
  • Snowy egret:  black beak with yellow face, black legs with yellow feet
  • Cattle egret:  yellow beak and dull yellow or dark legs. Small with short, chunky neck.
  • Immature little blue heron:  gray beak (tipped in black), yellow legs.
  • Not in Maine and Pennsylvania: the white morph of the Reddish egret: pink-and-black beak and dark legs (see photo at end).

First row of photos: Great egret + Snowy egret.
Second row: Cattle egret + immature Little blue heron.
Comparison of great egret and snowy egret (photos by Shawn Collins)

Comparison of catlle egret and little blue heron (photos by Shawn Collins)

Only the snowy egret has a black beak.   (Notice his fancy yellow feet).

The little blue is the only one with a gray beak(*), a hint that he’ll turn blue.  We won’t see him do this in western Pennsylvania because the juveniles fly south before winter.

When he’s halfway blue he’ll look very motley and match the marsh, like this one Shawn found in Texas.

Immature little blue heron with mottled blue and white (photo by Shawn Collins)

 

When he grows up you’ll never mistake him for an egret.

Little blue heron adult (photo by Shawn Collins)

He’ll be a little blue. ;)

 

(all photos by Shawn Collins)

p.s. (*) Jim Valimont points out that along the southern, Gulf, Caribbean and Pacific coasts the white morph of the Reddish Egret adds to the confusion.  Its beak resembles the immature little blue heron’s except that it’s two-tone pink and black.  It’s not found in Maine and Pennsylvania.

p.p.s  Steve Gosser contributed this photo of a white-morph reddish egret. Compare it to the first photo at top. Confusing? Yes!  But his legs are black and he only visits saltwater.
Reddish egret, white morph (photo by Steve Gosser)

 

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Sep 13 2013

Red Legs

Black guillemot in breeding plumage at Metinic Island, Maine (photo from Wikimedia Commons)

About the size of a pigeon, this northern alcid comes south to Maine for the winter.

I’ve seen black guillemots fishing close to rocky shores.  Some are still in their black-and-white breeding plumage (above). Most have changed to mottled white for winter.

Black guillemot in winter plumage (photo from Wikimedia Commons)

In either case they have bright red legs that match the insides of their mouths.

I can see their red legs through the water.

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

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Sep 02 2013

Resident or Migratory?

Flock of Canada geese on pond in Ottawa, Canada (photo from Wikimedia Commons)

Normally we don’t pay much attention to the immigration status of Canada geese but it’s going to be an important distinction in Pennsylvania when early Canada goose hunting season opens today.

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.  Here in Pennsylvania the birds so did well that there are nearly 280,000 resident maxima Canada geese, almost double the management goal of 150,000.

How do you determine the citizenship status of a Canada goose?   By time of year and location.  Only Pennsylvania residents are here in September.  Migratory geese won’t be leaving Canada until the lakes begin to freeze in October and even then the South James Bay population visits the northwest corner of the state (Lake Erie to Pymatuning) and the Atlantic population stays well east of the Appalachians and south of I-80.  In most of Pennsylvania, Canada geese are residents.

Why don’t our resident geese migrate?

Geese travel in family groups which collect at staging areas to join larger flocks.  The young geese learn the migratory paths from their parents.  If their parents don’t migrate the whole family stays put.  The reintroduced geese had no one to teach them to migrate so they and their descendants live here year round.

The resident geese know our habits and will gather in the no-hunt zones this month.  You may see more of them on our city rivers and in county parks in the days ahead.

Meanwhile, remember that fall is here and with it comes hunting season.  Wear blaze orange, especially if you visit State Gamelands where it’s required even if you’re not hunting.

 

(photo of Canada geese in Ottawa, Ontario from Wikimedia Commons.  These geese are migratory.  Click on the image to see the original)

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Aug 21 2013

Rescued!

Great egret trapped in high-strength fishing line (photo by John Beatty)

When fishermen and trappers abandon their lines in the water, they hurt unintended victims.  One careless individual nearly killed a great egret in York County, Pennsylvania.

Thanks to John Beatty, Ann Pettigrew, TriState Bird Rescue and a whole host of caring volunteers the bird was saved.  Here’s the story in John Beatty’s words:

On August 8th 2013 at William Kain Park I noticed an Egret was trailing behind some high-strength fishing line with a hook attached inside of the corner of its mouth. It was later discovered that this line was left behind by someone attempting to catch Snapping Turtles in the lake. I called the Fish & Game Commission and they dispatched out an officer but before he arrived a couple of local York County Parks employees happened to stop by as well. With a coordinated effort they were able to corral this bird into the woods, capture and retrieve it. By another coincidence there happened to be a veterinarian (Ann Pettigrew) of the Leader Heights Animal Hospital out taking photographs and she offered her help to bring the bird back to her office. The hook was removed from the bird’s throat and after being treated and nursed back to health it was released on August 18th. It was very nice that they invited me to come and take photos at the release of the bird.

Above, the egret struggles to remove the line but the hook is lodged in his throat.  In fact it has gone through and is protruding from his neck.

Below, county park naturalists Fran Velazquez and Kelsey Frey slogged through mud, water and thorns to catch the bird.  Wrapped in a towel, they are holding its beak (through the towel).  You can see its black feet near Kelsey’s gloved left hand.

GREG_rescue_9464685065_c040a60d68_c_rsz_johnbeattyGreat egret captured to rescue it from fishing line (photo by John Beatty)

 

At Leader Heights Animal Hospital, Dr. Ann Pettigrew removed the hook and heavy-duty string and treated the bird. Then she took it to Tri-State Bird Rescue for rehab.  In only ten days it was healthy and ready for release.

On August 18 everyone turned out to see the bird fly free.  Here Teresa Deckard of Bird Refuge of York County opens the box.

Great egret released (photo by John Beatty)

That’s one happy egret!

Thanks to all the good people who made this happy ending possible.

Don’t miss John Beatty’s beautiful photos of this egret’s rescue and release.  Click here or on any of the photos to see the entire story.

(all photos by John Beatty)

 

p.s. In the Comments I have transcribed Ann Pettigrew’s PABIRDS report of this egret’s rescue on August 8.

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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)

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Jun 17 2013

Doppler Effect

American avocet in flight (photo by Ingrid Taylar on Wikimedia Commons)

We all recognize the Doppler effect when an ambulance siren rises in pitch as it speeds toward us, then drops as it recedes. (Click here for a car horn example.)

Here’s a bird that uses that sound effect.

American avocets have many techniques for protecting their nests from predators.  They pretend to incubate a fake nest, then walk a few steps and pretend again.  They distract the predator by walking toward him in a teetering tightrope walk with wings outspread.  And they mob aerial predators before they can reach the nests.

But the most amazing technique is reserved for ground predators.  When avocets swoop to chase them away they shout at them, modulating their pitch to resemble the Doppler effect.  This is done so convincingly that the predator thinks the bird is approaching much faster than it actually is.  Run away!

Tex Sordahl discovered this while studying American avocets and black-necked stilts in the 1970s and ’80s.  Both use the Doppler sound effect.  I’m sure he got a dose of it during his study.

 

(photo by Ingrid Taylar via Wikimedia Commons.  Click on the image to see the original.)

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Mar 30 2013

Hunchbacked

Male common merganser in flight (photo by Steve Gosser)

Most birds fly with flat backs and heads up but some have this rounded hunchbacked look.

Here a common merganser flies with dipped neck and tail.  Loons always show this profile.

This shape is a good field mark.  Can you name other birds that fly like this?

(photo by Steve Gosser)

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