Outside My Window

Do owls hoot more when the moon is full?

Eurasian eagle owls do.  Maybe great horned owls do too.

In 2009 biologists conducted a study in Spain to find out if moonlight influenced Eurasian eagle owl vocalizations. They radio-tagged 26 breeding eagle owls and tracked them continuously during all phases of the moon.

When the scientists analyzed the data they found that the amount of hooting was directly correlated to the amount of moonlight.  On new moon nights the owls hardly hooted, but as the moon got brighter they had more to say and they said it from higher perches where their white throat patches gleamed in the moonlight as they spoke.

The white throat patch is important.

Like our great horned owls (Bubo virginianus), Eurasian eagle owls (Bubo bubo) have white throat feathers that are only visible when they hoot.  (The owl in this picture is hooting even though we can’t hear him.)  In bright moonlight the white throat patch is apparently a visual cue that backs up the sound.  Perhaps it helps the mate or rival find the bird that’s vocalizing.

Tonight the moon is full.   Will our great horned owls be talking?   Listen…

(photo by Adam Kumiszcza from Wikimedia Commons. Click on the photo to see the original)

January 20 – February 11 is the time for Pennsylvania’s Winter Raptor Survey (WRS) when volunteers drive prescribed routes and tally the number of raptors they see.

Many volunteers post their counts on PABIRDS where we learn that our most numerous winter raptors are red-tailed hawks.  (No surprise there!)

The reports include weather and snow cover conditions because this affects the number of raptors seen.  This year few routes have snow.

In a snowy year rough-legged hawks move south in Pennsylvania.  They breed in Alaska and Canada and winter in the Lower 48.  They’re found hunting in open meadows and brushy areas for mice, voles and rabbits.  But only where there’s snow cover.  If there’s snow, the rough-legs are here.  If not, they stay up north.

Two years ago we had a lot of snow — so much that it was hard to drive the routes.  (Remember the two feet of snow February 5-9, 2010?)   This year it’s easy to drive but the birding isn’t as good.

I’m not asking for a return to the snow of 2010 but snow in moderation would be nice, if only for rough-legged hawks.

Steve Gosser was lucky to see this one at Pymatuning on January 14.

(photo by Steve Gosser)

If you want to see bald eagles in Pennsylvania, winter’s a great time to do it.

Bald eagles eat fish so they always live near open water.  When the lakes freeze they move to the rivers.  When the rivers freeze they congregate near the open tailwaters at dams.

And thus was born the Annual Eagle Watch at Kinzua Dam in Warren County, PA.

This year’s event at the Big Bend Recreation Area will be held on Saturday, February 4 from 8:00am to 2:00pm.   View the eagles through spotting scopes at three observation areas:  Big Bend Visitor Center (warm up indoors with hot chocolate!), Riverside Watchable Wildlife Trail and Viewing Platform, and on the dam.  Those over 18 must show a photo ID to walk out on the dam.

In addition to eagle watching David Donachy of the PA Game Commission will present a program on the success of Pennsylvania’s bald eagle restoration, and Kinzua Cachers will hold a geomeet to find several temporary caches in the area.

The event is free, sponsored by US Army Corps of Engineers, the Pennsylvania Game Commission, Penn Soil Resource Conservation and Development Council, Kinzua Cachers, and the Allegheny Outdoor Club.

While you’re up at Kinzua Dam you’re just 10 minutes from downtown Warren where WQED-FM’s morning host Jim Cunningham recommends the Plaza Restaurant.  Staying overnight?  You can get a discount at the Warren Hampton Inn if you tell them you’re coming for the Eagle Watch.

Click here for more information, or call Steve Lauser, U.S. Army Corps of Engineers, at (814)726-0661 or Bill Massa, Allegheny Outdoor Club, at (814)723-2568.

Keep your eyes open for eagles as you drive upstate.  Eagle sightings are more common than ever before.  Here are some recent sightings in Pennsylvania.

(photo by Steve Gosser, near Crooked Creek dam in Armstrong County)

Winter’s back!  After a week of highs in the 40′s and 50′s, this morning dawned at 18 degrees F with winds gusting to 32mph and a wind chill of 1 degree.  Brrrr!

But… with winter’s return there’s a report on PABIRDS of a snowy owl in Somerset County.

This winter “snowies” are coming south in big numbers.  From New Jersey to Oregon, from Ohio to Oklahoma more of them are visiting this year than anyone expected.  In November Jesse Ellis created this collaborative Google map of snowy owl sightings, showing the beginning of the owl invasion.  (It was last updated in December, then moved to eBird where the number of pushpins isn’t as limited.)

Wisconsin has seen a lot of snowy owls.  By December 10 birders had already counted 80 in a state that usually sees 10 in an entire winter.  This influx did not go unnoticed by other birds of prey.  On November 21, Luke Kvapil was about to photograph an owl perched at Milwaukee’s harbor when a peregrine falcon flew in and took a swipe at the bird.  Click here and scroll down to see the peregrine harassing the snowy.

As of this writing there’s no information on the location of the Somerset County snowy owl, but several intrepid birders are looking for it.

Intrepid is the word!  If it’s winter in Pittsburgh, Somerset County is the arctic.

Perhaps that’s why the snowy owl is there.

(photo by Kim Steininger)

The names of these owls used to be the reverse of each other.

The eastern screech-owl on the left used to have the scientific name Otus asio.  In 2004 the American Ornithologists’ Union renamed him to Megascops asio, but his old name is still found on the web.

The long-eared owl on the right is still named Asio otus.

For reasons of symmetry, I wish the AOU hadn’t renamed the screech-owl.

“Otus Asio, Asio Otus” was rather fun.

(both photos are from Wikimedia Commons.  Click here to see the original of the eastern screech-owl.  Click here to see the original of the long-eared owl.)

Good morning, “Hunter!”

That’s the nickname Bill Powers gave to this eastern screech-owl roosting in an owl box in his Murrysville backyard.

Bill is founder and CEO of PixController, a company that specializes in wildlife streaming webcams.  PixController set up the National Aviary penguin cam, the Gulf Tower and Pitt peregrine streaming cams, and the famous Lily The Bear cam which will be live again soon.

To demonstrate PixController’s expertise — and for fun — Bill has four streaming cameras set up at home.  Three are at ground-based feeding stations.  The fourth is in this owl box.

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In October Bill noticed an eastern screech-owl roosting in his only owl box so he set up four more boxes in hopes of attracting a nesting pair in the spring.  At first the owl preferred box #1 but he didn’t roost there every day, though he sometimes left food for later consumption.  One day while the owl was away a squirrel built a nest over the owl’s cache and the owl never used that box again.

Now what?  Bill waited and watched until he knew which of the other boxes the owl like best.  Here’s how he figured it out:

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After Hunter chose a new box, Bill installed the streaming webcam with an infrared light so we can see the owl even when the box is dark inside.  That’s why Hunter looks white in the webcam snapshots.

In today’s photo (at top), Hunter is facing the hole with his head bowed a little while he sleeps.  We see the top of his head and his back.  Reddish sunlight is brightening the box hole and two cracks at the front corners of the box.  Today Hunter brought a dark-colored mouse-y snack with him which he cached on the right.

Here are more pictures of Hunter sleeping, looking up and flying out.

You can watch Hunter live today (December 18) by clicking here or on the first photo above.  If you miss him today and he’s not there when you look for him, check back the next day.  Hunter doesn’t use this box every time.  He has other places to roost, but he’ll be back.

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(photos by Bill Powers and PixController Wildlife Camera #4)

p.s. Click here to see all four PixController cameras on one page.

Coming next Wednesday on PBS Nature is a raptor story nest-watchers can relate to.

Jungle Eagle follows filmmaker Fergus Beeley as he monitors a harpy eagle nest in Venezuela’s Orinoco River valley.  Over a period of nine months he shows us the life of an eaglet and his family, from newly hatched chick to young adulthood.  The story is dramatic.  The lifestyle of these eagles makes it dangerous.

Harpy eagles live in the South American rainforest and are the largest eagle in the western hemisphere.  They dwell at the top of the canopy and eat monkeys and sloths from the trees. They kill by surprise.

The adults are top predators but the young are vulnerable.  When the chick is small his mother must guard him.  Even the monkeys that become his food could eat him.

Fergus Beeley shows this by filming from a tree stand and using a nestcam.  Peregrine nest watchers will see parallels between the harpy eagles and our favorite raptor:

• The mother bird guards the chick and won’t leave him while he’s small.
• She calls her mate to bring food.  “Come NOW!”
• When he delivers a meal, she snatches it and barely says thank you.
• Though a powerful raptor, she is very tender with her chick.
• The baby grows into a fully feathered teenager who begs from his parents.

Inevitably there are nestcam problems, but they’re more dangerous to fix than anything we ever encounter.  Peregrines fiercely defend their nests and harpy eagles do, too.  But harpy eagles are huge and they’re skilled at killing primates.  And what are humans?  Large primates!

In the end the eaglet reaches adulthood and starts to hunt on his own.  As adults, harpy eagles are powerful, self sufficient birds.  The real danger they face is extinction because people cut down the rainforest these birds require for life.

Watch Jungle Eagle on PBS Nature on Wednesday, November 9 to see beautiful footage of our hemisphere’s most powerful bird.  On WQED the show is at 8:00pm EST.

(photo of a harpy eagle from PBS Nature)

Last month Cris Hamilton visited Conneaut Harbor, Ohio to photograph visiting gulls and terns at the Lake Erie shore.

While there she saw two immature bald eagles chasing each other.  One had a fish.  The other wanted it.

Ooops!

I wonder if the fish fell in the lake and survived this ordeal.

Click on Cris’ photo to see her Conneaut Harbor album.

(photo by Cris Hamilton)

Yesterday at the lake at Moraine State Park I saw some blue jays across the cove.  I didn’t pay much attention until I heard an unusual noise coming from their direction.  Was there a green heron over there?

I checked with my binoculars.  No green heron.  Just three blue jays and an immature sharp-shinned hawk. 

The jays were having fun.  The hawk was not.

The blue jays loafed in the trees and waited for the hawk to attack.  The sharpie swooped but the jays always evaded him.  One jay in particular taunted the hawk by flying close and allowing the hawk to chase him.  This must have given the jay an adrenaline rush because the sharpie was faster and sometimes nearly tagged the jay.  At those exciting moments the jay made a green heron noise.

This game went on for 20 minutes.  The hawk could not win.  He was exactly the same size as the blue jays and his speed and anger were no match for their cunning brains.  The sharpie burned a lot of energy but he was not going to quit.

It ended when the “green heron” jay got bored and flew away.

At last the sharp-shinned hawk could focus on finding a meal of an appropriate size.

(Immature sharp-shinned hawk and blue jay; both photos by Marcy Cunkelman)

According to migration statistics from Hawkcount.org, the bulk of broad-winged hawk migration passed through Pennsylvania in mid-September with one last pulse last Tuesday.

Most of them followed Kittatinny Ridge, the easternmost spine of the Appalachian Mountains where Hawk Mountain Sanctuary is located.  Here are the three highest broad-winged counts at Hawk Mountain this month:

• Sept 13 — 1,572
• Sept 17 — 2,813
• Sept 19 — 1,701

You might think this means that hawks travel in flocks but they don’t.  Instead they watch each other for flight cues.  If one hawk finds a thermal with good lift, others fly over and rise on it as well.  Soon they form a “kettle” of hawks stirring round and round in the rising air.  As each one  reaches sufficient altitude it sets its wings and glides southward to find the next thermal.

After the broad-wings leave Pennsylvania they make their way to the Texas Gulf Coast and follow the eastern edge of the Gulf of Mexico on their way to their wintering grounds in South America.  By the time they pass Veracruz, Mexico, all the broad-wings of North America are concentrated in a narrow corridor.  Their numbers at Veracruz are astonishing, as shown in their three highest counts this month and in the video above.

• Sept 23 — 136,376
• Sept 24 — 128,272
• Sept 22 –  68,724

I tried to imagine 136,000 hawks in my Pittsburgh neighborhood and my first thought was, “There isn’t enough food here for 136,000 hawks!”  But there is — for a short time — in Veracruz.

Broad-winged hawks eat small mammals, reptiles, amphibians, large insects and songbirds.  Right now they’re traveling with millions of dragonflies and songbirds who are also on migration.

That’s why they migrate in September.  That’s why there’s a spectacle of broad-winged hawks.

(video from Veracruz Hawkwatch on YouTube)