Archive for the 'Bird Behavior' Category

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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Aug 29 2016

Peripatetic

Hope (69/Z) preens at the Tarentum Bridge, 28 Aug 2016 (photo by Anthony Bruno)

Hope (69/Z) preens at the Tarentum Bridge, 28 Aug 2016 (photo by Anthony Bruno)

Peripatetic: adjective [1] traveling from place to place, especially working or based in various places for relatively short periods. (definition from Google search)

Hope (69/Z, black/green) is a peripatetic peregrine falcon.  For five years she called the Tarentum Bridge her home until last spring when she nested at the Cathedral of Learning.

In my experience, peregrines stay put when they’ve claimed a prime territory but Hope does not.  On Friday she flew 15 miles back to Tarentum and set up shop for several days.

She’s so comfortable at Tarentum that, unlike her habits at Pitt, she perches in easy view.

Last weekend Tony Bruno and Steve Gosser stopped by for some great photographs. Above, Tony got a photo of Hope’s bands while she was preening.  Look how close she is!

Below, Steve caught the action when a curious mourning dove came close while Hope was eating. The dove escaped.

Peregrine falcon, Hope, confronts a mourning dove at the Tarentum Bridge, 27 Aug 2016 (photo by Steve Gosser)

Peregrine falcon, Hope, confronts a mourning dove at the Tarentum Bridge, 27 Aug 2016 (photo by Steve Gosser)

Peregrine falcon Hope stirs up a watchful mourning dove at the Tarentum Bridge, 27 Aug 2016 (photo by Steve Gosser)

Peregrine falcon Hope stirs up a watchful mourning dove at the Tarentum Bridge, 27 Aug 2016 (photo by Steve Gosser)

...and the mourning dove escapes at the Tarentum Bridge, 27 Aug 2016 (photo by Steve Gosser)

…and the mourning dove escapes at the Tarentum Bridge, 27 Aug 2016 (photo by Steve Gosser)

 

Apparently three days were long enough at Tarentum because Hope flew back to the Cathedral of Learning yesterday afternoon.  She appeared on the falconcam at 3:30pm, dug a little at the scrape and then perched and preened.

You can see her band colors below.  Her greenish right-leg band and black/green left-leg band are a diagnostic combination.

Hope reappears at Pitt, 28 Aug 2016, 3:30pm (photo from the National Aviary falconcam at Univ of Pittsburgh)

Hope reappears at Pitt, 28 Aug 2016, 3:30pm (photo from the National Aviary falconcam at Univ of Pittsburgh)

 

And here’s her familiar face.

Hope at Pitt, 28 Aug 2016, 3:34pm (photo from the National Aviary falconcam at Univ of Pittsburgh)

Hope at Pitt, 28 Aug 2016, 3:34pm (photo from the National Aviary falconcam at Univ of Pittsburgh)

 

She probably was at the Cathedral of Learning during last night’s terrific thunderstorm, but who knows.

Hope doesn’t perch in sight at Pitt so I’m never sure if this peripatetic bird is actually there.

 

(photos by Anthony Bruno, Steve Gosser and the National Aviary falconcam at Univ. of Pittsburgh)

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Aug 22 2016

Babies, It’s Hot Outside

Screenshot from Science video about zebra finch nest songs (Click on the image to see the video)

Screenshot from Science Magazine video on zebra finch nest songs (Click on the image to see the video)

Bird news from last week, in case you missed it …

Many birds talk to their eggs and there’s evidence that the eggs hear and respond.  For instance, superb fairywrens sing to their eggs and before they hatch the babies sing back!

Now scientists at Deakin University in Australia have discovered that in zebra finches what the eggs hear and how they respond is even more amazing than we knew.

In the last days of incubation, zebra finches (Taeniopygia guttata) sing a special song to their eggs but only when it’s hot outside — greater than 26 degrees C (78.8 degrees F).

The eggs hear the song and it changes their lives.

After they hatch, babies who heard the “hot call” grow more slowly than those who didn’t.  Not only are the “hot call” babies smaller as adults but they’re more successful breeders in a hot climate.  Surprisingly, this effect extends into later generations.

Small bodies cope better with heat than large ones, so signalling for a smaller size is a great adaptation for a warming climate.

But how does the zebra finch song bring about this result?

Click here to watch the video and read about this amazing feat.

 

(screenshot from Science Magazine video about zebra finch vocalization. Click on the screenshot to see the video)

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Aug 18 2016

Backyard Hawk

Red-tailed Hawk on Solomon's deck (photo by Michael Solomon)

Red-tailed Hawk on Solomon’s deck (photo by Michael Solomon)

On Throw Back Thursday:

If there’s a bulky hawk in your backyard that ignores you like this, I bet I can identify it without ever seeing it.  In western Pennsylvania, I’m 90% sure it’s a juvenile red-tailed hawk.

Young red-tailed hawks are so focused that they tune us out.  Read about this backyard bird in the 2009 article:

Single-mindedness

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Aug 14 2016

Update Your Scorecard

Magnum at the Cathedral of Learning nest, 12 August 2016, 5:15pm (photo from the National Aviary falconcam at Univ of Pittsburgh)

Magnum at the Cathedral of Learning nest, 12 August 2016, 5:15pm (photo from the National Aviary falconcam at Univ of Pittsburgh)

Get ready to update your scorecard.  There have been two! changes in female peregrine ownership at the Cathedral of Learning so far this weekend.

Friday evening “NR” saw a black/red banded female at the nest and posted a comment that Magnum was back on August 12 at 5:15pm — that’s 17:15 time code on the camera.  The photo above clearly shows Magnum’s bands.

Then Saturday night, August 13 at 6:52pm, members of Pittsburgh Falconuts saw Hope on camera calling loudly.  Terzo was nearby but he waited almost four minutes to join her.  Though her black/green bands are hard to read here, we know it’s Hope based on multiple snapshots.  She visited the nest again alone in the 8 o’clock hour.

Hope returns to the nest, 13 August 2016 at 6:52 pm (photo from the National Aviary snapshot camera at Univ of Pittsburgh)

Hope returns to the nest, 13 August 2016 at 6:52 pm (photo from the National Aviary snapshot camera at Univ of Pittsburgh)

 

So here’s the state of play at the Cathedral of Learning pre-dawn on August 14.  I’m writing this before they wake up and change things again!

  • 30 Nov 2015: Hope arrives at the Cathedral of Learning
  • 8 April 2016 (same day):  Hope retains site after unbanded immature female visits the nest.
  • 23 April 2016 (same day): Hope retains site after a banded adult female (black/red) visits the nest.
  • 22 June 2016:  Magnum (black/red 62/H) claims the Cathedral of Learning.
  • 24 June 2016: Hope regains the site.
  • 2 August 2016: Unbanded young female claims the Cathedral of Learning.
  • 6 August 2016: Hope regains the site.
  • 12 August 2016:  Magnum (black/red 62/H) claims the Cathedral of Learning.
  • 13 August 2016: Hope regains the site.

As of this writing I have no idea where Magnum is but she knows her way around.  She’s been to the Cathedral of Learning before, possibly on April 23 and certainly on June 22.  Her home base has been the Neville Island I-79 Bridge, to which she returned after her last visit.

I don’t know how long Hope will stay this time.  Don’t even ask!

As I said on August 6, no humans ever see how these turnovers occur.  As far as I can tell no peregrines get hurt.

Thank you to NR and to all of you who check the Cathedral of Learning falconcam for peregrine activity.  Without your help we’d never know how interesting this summer has been.

 

(photo from the National Aviary falconcam at Univ of Pittsburgh)

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Aug 08 2016

Asleep In Flight

Published by under Bird Behavior

Great frigatebird carrying sleep monitoring equipment (photo by Bryson Voiron from Nature Communications article)

Great frigatebird with sleep monitoring equipment (photo by Bryson Voiron from Nature Communications article)

On transoceanic airplane trips the passengers try to sleep in flight but the pilots stay awake. (Thank heaven!)  Many birds, including swifts, sandpipers and songbirds, fly non-stop over the ocean for so long that scientists guessed the birds would have to sleep along the way.  But how? Wouldn’t they crash?

As part of their daily lives, great frigatebirds (Fregata minor) fly non-stop for weeks, eating flying fish and ocean-surface food in trips that can span two months and 22,000 miles.  These large birds live over the ocean but not on it because their feathers aren’t waterproof.

Great frigatebirds have got to sleep some time so researchers led by Niels C. Rattenborg of the Max Planck Institute fitted more than a dozen females with instruments to measure sleep and flight time.  The great frigatebird, above, has a sleep-measuring headset and a GPS backpack.

The results of the sleep study were surprising.

Scientists knew that, on land, birds can sleep with only half the brain while the other half stays alert for danger. They found that great frigatebirds half-sleep in the air, too, but sometimes both hemispheres sleep at once for more than two minutes.  They do it while circling on an updraft.

Another surprise was how little the birds slept, clocking only 42 minutes/day in the air compared to 12 hours/day on land.  If they were humans they’d be seriously sleep deprived.

Amazingly the frigatebirds’ performance was not affected by lack of sleep and when they got home they caught up on sleep in their first days on shore.  How many of us wish we could live like that!

Find out more here at Gizmodo or in the report here in Nature Communications.

 

(photo of great frigatebird with sleep measuring equipment by Bryson Voiron from  “Evidence that birds sleep in flight,” Nature Communications)

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Aug 05 2016

His Feathers Sing

The male club-winged manakin (Machaeropterus deliciosus) uses dance and sound to attract the ladies but he doesn’t open his mouth.  He uses his wings!

Watch and listen as he bows and flares.  The loud buzzy noise is made by his secondaries.  Cornell Lab writes:

The secondary wing feathers of the male Club-Winged Manakin, a bird from South America, are large and rigid. He strikes them together at about 107 times per second to create a buzzing sound, which is used during courtship displays.

Ornithologists have known for a long time that the males’ secondary feathers are deformed.  This 1871 drawing shows the difference between the males’ deformed and the females’ normal feathers.

Modification of Manakin Pipra deliciosa = Machaeropterus deliciosus wings for sound production, from Darwin's - The Descent of Man

Modification of Manakin Pipra deliciosa = Machaeropterus deliciosus wings for sound production, from Darwin’s – The Descent of Man

 

Now that we have high definition video we can see why they’re like that.  He makes his feathers sing.

 

p.s.  Click here for the location of secondary wing feathers.

(video from Cornell Lab of Ornithology on YouTube. Illustration from Wikimedia Commons; click on the image to see the original.)

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