Archive for the 'Bird Behavior' Category

Oct 14 2016

Why Do Peregrines Like Bridges?

Hope (69/Z) at the Tarentum Bridge, July 2012 (photo by Steve Gosser)

Hope (69/Z) at the Tarentum Bridge, July 2012 (photo by Steve Gosser)


Out in the wilderness, peregrine falcons nest on sheer cliffs.  Pittsburgh doesn't have those cliffs but we do have nesting peregrines at two sites on buildings and five on bridges.

It's easy to see that a tall building resembles a cliff ...

Cathedral of Learning (photo by Kate St. John)

... but bridges are open structures without sheer walls.
Tarentum Bridge nestbox project, The Bucket Truck, 27 Feb 2015 (photo by Kate St. John)

Why do peregrines like bridges?

I found the answer in a blog post from The Center for Conservation Biology.  CCB monitors peregrines in Virginia where many falcons prefer bridges at the coast.

As you read the article linked below, watch for a photo of the Benjamin Harrison Lift Bridge where Hope (black/green, 69/Z) pictured above, was banded. She has nested at both kinds of sites in Pittsburgh:  six years at the Tarentum Bridge and now at a building, the Cathedral of Learning.


p.s. The article explains that peregrine nestlings from the Lift Bridge are hacked in the Shenandoah Mountains. Hope was one of those birds.

(photo credits:
Hope at Tarentum by
Steve Gosser
Cathedral of Learning and Tarentum Bridge by Kate St. John
peregrine on nest by Bryan Watts linked from CCB blog

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Oct 09 2016

Favored By Cardinals

Published by under Bird Behavior,Plants

Climbing false buckwheat (photo by Kate St. John)

Climbing false buckwheat (photo by Kate St. John)

This vine looks messy but its seeds are good food for birds and mammals.

Though climbing false buckwheat (Fallopia scandens a.k.a. Polygonum scandens) is related to smartweed and Japanese knotweed, it's a native perennial vine. Unfortunately it looks invasive because its red stems climb over nearby vegetation to get close to the sun.

Its small whitish flowers bloom from August to October but they aren't much to look at.

Climbing false buckwheat (photo from Flora Pittsburghensis)

Climbing false buckwheat (photo from Flora Pittsburghensis)

Last week in Schenley Park I found a chipmunk and four cardinals hiding among the tangled vines, quietly munching false buckwheat seeds.

The seeds are favored by cardinals.


(seed photo by Kate St.John. Flower photo from Flora Pittsburghensis; click on the photo to see the original)

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Oct 03 2016

Pigeons Can Read 4-Letter Words

Pigeons (photo from Wikimedia Commons)

Pigeons (photo from Wikimedia Commons)

A new study of rock pigeons indicates they can read four-letter words ... sort of(*).

Researchers at the University of Otago in New Zealand and Ruhr University in Germany quizzed four pigeons on their orthographic abilities.

According to Science Daily, "In the experiment, pigeons were trained to peck four-letter English words as they came up on a screen, or to instead peck a symbol when a four-letter non-word, such as 'URSP' was displayed. ... The pigeons correctly identified the new words as words at a rate significantly above chance."

Eventually the four birds in the experiment recognized 26 to 58 real words and correctly labelled over 8,000 as non-words.  They're the first non-primate species found to have this ability.

So yes, pigeons know when they're looking at a real 4-letter word but like naïve children they don't know what it means.

Learn more about the study here in Science Daily.


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

(*) The study shows that pigeons can figure out letter-combinations. Pigeons have no reading comprehension so, literally speaking, they cannot read.

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Sep 27 2016

He Eats Needles


Here's a bird you'll never see in Pennsylvania.

The spruce grouse (Falcipennis canadensis) is a resident of the northern forest in Canada, Maine, Minnesota and the northern Rockies.  Though he resembles our state bird, the ruffed grouse, his diet keeps him north of us.

In winter our ruffed grouse (Bonasa umbellus) eats buds, twigs, catkins, ferns and fruit -- easy food to find in Pennsylvania.

Not so the spruce grouse.  His winter diet is conifer needles.  They're so hard to digest and he has to eat so many of them to stay alive that his digestive system changes in the fall.  According to Cornell's All About Birds, his "gizzard grows by about 75 percent, and other sections of the digestive tract increase in length by about 40 percent."  Before the snow falls he stocks up on grit so his gizzard can grind up the needles.

In September 2012 Sparky Stensaas found this spruce grouse swallowing road grit and feasting on a tamarack in northern Minnesota.  Tamaracks loose their needles in October so the grouse had to eat them right away.

This bird eats spruce needles, too.  That's why he's a spruce grouse.


Click here to see the video full screen and read Sparky's description of what this grouse was up to.

(video by Sparky Stensaas)

* Tamaracks are larches, deciduous conifers whose needles turn yellow and drop in the fall.

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Sep 23 2016

Birds Take Flight Before Earthquake

Published by under Bird Behavior

Flock takes off (photo by Chuck Tague)

Flock takes off (photo by Chuck Tague)

In case you missed it early this month ...

Oklahoma is a place that rarely had earthquakes until hydraulic fracking brought deep well injection to the state in 2009. Since then fracking disposal has awakened previously unknown fault lines with frequent and usually mild tremblors.

Then on 3 September at 7:02am a magnitude 5.8 earthquake struck Pawnee, 72 miles northeast of Oklahoma City as the crow flies.  And, yes, the crow flew.

The birds in the area somehow knew the earthquake was coming and took flight before it happened.  We know this because they appeared on Oklahoma City's weather radar as an expanding cloud as much as 15 minutes before the quake!

See the radar image here and read more about birds' extra earthquake sensors in the Washington Post.


p.s.  Residents on the ground at Pawnee weren't so lucky. See the damage at Newson6.

(photo by Chuck Tague)

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Sep 19 2016

Bathing On A Leaf

Published by under Bird Behavior

Here's a bird bathing technique I had never seen before ... until yesterday.

Sunday morning Jack and Sue Solomon led a Three Rivers Birding Club outing at Frick Park. We all hoped to see warblers but the birds were sparse and badly backlit in the treetops.

A passing shower halfway through the walk was just what we needed.  When the rain paused, a few birds were at eye level.  One of them was a Kentucky warbler who drew our attention by bathing on top of sumac leaves.

The hummingbird in this video is doing the same thing.  Watch at the 00:37 mark when he uses a leaf like a bathtub.  Who knew!

p.s.  Click here to see what a Kentucky warbler looks like.


(video by RM Videos on YouTube)

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Sep 14 2016

Spread Your Wings

Published by under Bird Behavior

Two double-crested cormorants drying their wings (photo by Steve Gosser)

Two double-crested cormorants drying their wings (photo by Steve Gosser)

Yesterday's blog about double-crested cormorants reminded me there other birds that spread their wings to dry, not fly.  Some of them aren't even wet when they do it.

Cormorants' feathers are wettable but a layer near the skin stays dry so they don't get very cold.  This allows them to live in the North Atlantic and the Aleutians (see species list below) where they sometimes "dry" their wings in fog or rain.

Anhingas (Anhinga anhinga) aren't so lucky.  When they go swimming they get soaked and have to get out of the water to warm up.  This limits their distribution to warm climate zones.

Anhinga sunning at Ding Darling NWR, Florida (photo from Wikimedia Commons)

Anhinga sunning at Ding Darling NWR, Florida (photo by Dick Daniels from Wikimedia Commons)


Turkey vultures (Cathartes aura) are often dry when they spread their wings because they're doing it to warm up.  Overnight their body temperature drops so a good sunning is welcome in the morning.

Turkey vulture sunning at Bluff, Utah (photo from Wikimedia Commons)

Turkey vulture sunning at Bluff, Utah (photo from Wikimedia Commons)

So there's more than one reason to spread your wings.  Read more about it here.


(photo of double-crested cormorants by Steve Gosser. Anhinga and turkey vulture photos from Wikimedia Commons. Click on the Wikimedia images to see the originals.)

p.s. Cormorant species list:  In North America the genus Phalacrocorax ("sea raven") has six members, though one is rare.


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Sep 13 2016

Wettable Feathers

For a bird that eats fish for a living, what possible advantage could there be in having feathers that get waterlogged?

Water beads up on the plumage of ducks and loons but the feathers of double-crested cormorants (Phalacrocorax auritus) are "wettable" so they spend more than half their day out of the water loafing, preening and spreading their wings to dry as shown in the video above(*).

This wettability is not caused by a lack of oil on their feathers.  Instead it's the feathers' structure that allows them to get wet.

Combined with their solid, heavy bones, wettable feathers make cormorants less buoyant so it's easier to stay underwater and hunt for fish.

The proof is in the eating.  Ta dah!  He caught a large catfish.

Double-crested cormorantwith catfish, Everglades National Park (photo from Wikimedia Commons)

Double-crested cormorant with fish, Everglades National Park (photo from Wikimedia Commons)


Watch for double-crested cormorant numbers to build in western Pennsylvania this fall as they migrate south for the winter.


p.s. *Note: The bird in the video has a white feather or debris on top of his beak. It's not a field mark.

(video from Cornell Lab of Ornithology, photo by R. Cammauf, National Park Service, via Wikimedia Commons. Click on the image to see the original.)

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Sep 07 2016

Hey, People! Work With Me

Greater honeyguide (photo by Wilferd Duckitt via Wikimedia Commons)

Greater honeyguide (photo by Wilferd Duckitt via Wikimedia Commons)

Domestic birds work for us but here's a wild bird who chooses to work with us.

Greater honeyguides (Indicator indicator) are wild birds in Africa known for leading humans to honey.  They eat bee eggs, larvae and beeswax but often can't get at them because the bees fight them off.  So the birds enlist our help, "Hey, humans! Work with me."

Chattering and fluttering in front of us, honeyguides lead us to the hives where we use smoke to subdue the bees and axes to open the tree trunks where the hives are hidden.  We get the honey.  The honeyguides get the insects and wax.

This active solicitation has gone on for thousands of years.  In July we learned a new twist in the story.

Claire Spottiswoode studied greater honeyguides in Mozambique and found that the solicitation works both ways.  People have a special call that means, "Come, honeyguide! Let's go look for honey together." The birds arrive and lead the way.

The calls vary by region. For instance, there's one sound in Mozambique, another in Tanzania.  Listen to the story on NPR to hear them.

"Hey honeyguide! Come work with me."

How the birds learned our calls is still unknown.


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

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Aug 31 2016

It’s Time To Watch Chimneys

Across North America chimney swifts (Chaetura pelagica) and their look-alike western cousins, Vaux's swifts (Chaetura vauxi), are migrating south for the winter.


Chimney swift trio (photo by Jeff Davis)

Chimney swift trio (photo by Jeff Davis)

Swifts eat flying insects so they migrate during the day when the insects are out.  On hot days they circle high, coursing back and forth in the clouds of bugs.  It doesn't look like organized migration but they're tending ever southward while they eat.

At dusk the swifts gather at big chimneys, circle in a vortex, then pop into the chimneys to roost, as shown in the video.  On cold rainy days they roost during the day to conserve energy when the bugs don't fly.

Vaux's swifts are on their way to Central America but the chimney swifts will go much further, crossing the Gulf of Mexico to spend the winter in Columbia, Peru, Ecuador and western Brazil. I wonder if their over-water migration gave them the species name "pelagica."

For the next several weeks, watch chimneys at dusk to see the swifts.  Click here for suggested sites in Pittsburgh.


(video from Cornell Lab of Ornithology on YouTube, swifts photo by Jeff Davis)

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