Archive for the 'Bird Behavior' Category

Oct 21 2014

Tuck Your Wings

Published by under Bird Behavior

Steppe eagle with backpack tracking device (photo by Graham Taylor, Creative Commons license)

Ever since we invented airplanes engineers have wondered how birds can withstand gusty turbulence that our light aircraft cannot.

To find out, researchers from Oxford University’s Department of Zoology fitted a captive steppe eagle (Aquila nipalensis) with a flight data recorder.   Steppe eagles are large, similar to our golden eagle, so the 75g black box was not a burden for ‘Cossack.’

As he flew at Brecon Beacons, Wales researchers filmed Cossack’s maneuvers, then tied the video to the recorded airspeed, acceleration, rotation rate, and GPS location.

Oxford reports, “An analysis of data from 45 flights revealed that in windy conditions the eagle would collapse its wings in response to particularly strong gusts rather than hold them out stiffly as an aircraft would. During these ‘wing tucks’, the bird’s wings were briefly (for around 0.35 seconds) folded beneath its body so that it was effectively ‘falling’. The results suggest that these ‘wing tucks’ may occur up to three times a minute in some conditions.”

Professor Graham Taylor said, “We think that, rather like the suspension on a car, birds use this technique to damp the potentially damaging jolting caused by turbulence.”

Have you seen large birds do this?  I have, but I didn’t realize what it was.  I know, for instance, that turkey vultures hate to flap but I’ve seen them crest a hill and suddenly tuck their wings.  Aha!  They probably encountered turbulence.

See raptors tuck their wings and, in November, golden eagles at the Allegheny Front Hawk Watch.  If you’d like a guided tour to the Allegheny Front sign up for the National Aviary’s November 1 bus trip.

For more on this study see the Journal of the Royal Society Interface.

 

(photo of ‘Cossack’ by Graham Taylor, Creative Commons license.  Click on the image to see the original article and image at Science Daily)

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Oct 17 2014

Who Owns The Sky?

Last week’s sensational bird video showed a red-tailed hawk attacking a personal drone in Cambridge, Massachusetts (above). The drone lost.

Drones are popular because they’re easy to fly and come with onboard videocams.  Open the box, assemble a few pieces, turn on the camera, and fly it up and into … trouble, if you aren’t careful.  Novices don’t realize who owns the sky.

When Amazon Prime announced plans last December to deliver packages using drones it sounded simple but the initial hype failed to mention the regulatory, mechanical and natural hurdles.   Blog posts at Slate and The Atlantic immediately set the record straight.

At Slate Konstantin Kakaes explained how unreliable drones are right now and how much the FAA controls the airspace.  Drone pilots looking for killer video ignore the law to their peril and have been arrested.

The next day Nicholas Lund at Slate and Megan Garber at The Atlantic were quick to mention the bird factor.  Click on The Atlantic link to see five videos of angry bird attacks.

The FAA limits personal drones to a 400-foot ceiling — that’s below the 30th floor of the Cathedral of Learning — but birds of prey limit flying threats to a much lower level than that.  Red-tailed hawks near the Cathedral of Learning are frequently reminded that peregrines own the airspace above the treetops.  Drone pilots could learn a valuable lesson from a bald eagle who strayed into Dorothy’s zone.

Birds have owned the sky for 160 million years.

Take that you pesky airplane!

 

(drone video by Christopher Schmidt on YouTube. Click on Christopher’s link to read more about the hawk video)

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Oct 15 2014

Hybrid Migration

Swainson's Thrush (photo by Matt Reinbold, Bismarck ND, from Wikimedia Commons)

If you’re a Swainson’s thrush of mixed parentage you’ll probably pick a bad migration route.  It’s in your genes.

In eastern North America we see only one subspecies of Swainson’s thrush, the olive-backed (above), but in British Columbia there are two.  The russet-backed subspecies breeds along the Pacific coast and follows the coast to spend the winter in Mexico and Costa Rica.  The olive-backed subspecies breeds in the interior and migrates across the continent and the Gulf of Mexico to winter in South America.

Where their breeding ranges meet the thrushes pair up without regard to these distinctions.  Their hybrid offspring inherit a mixture from their parents, including mixed coloration.

Kira Delmore at the University of British Columbia wondered if the hybridization extended to their migration routes so she tagged hybrid Swainson’s thrushes with light-level geolocators to track their routes.

The data proved that their migration routes are inherited and that those of mixed parentage inherit a blend.  While each parent would have followed the Pacific coast or a safe route across the continent, the hybrids chose novel and dangerous compromises between the two paths.

“Instead of taking well-trodden paths through fertile areas, these birds choose to scale mountains and cross deserts,” said Delmore.

The dangerous routes probably cause more hybrids to die on migration than their pure counterparts, thus keeping the subspecies distinct.  Says Delmore, “The self-destructive behavior of hybrids could be helping to maintain the great diversity of songbirds we enjoy.”

Read more about this study here at Science Daily.

 

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

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Sep 26 2014

Storing Food

 

Fall’s here now. Winter’s coming.  Birds who stay through the winter are already using their best survival strategies.

Blue jays bury acorns, nuthatches hide seeds in bark crevices, but the real champion of food storage is a bird who doesn’t live in Pennsylvania.

Check out this Cornell Lab video from southern California.  I think California is a warm place where a bird couldn’t possibly need a large pantry but acorn woodpeckers never stop.

 

(video from Cornell Lab of Ornithology on YouTube)

p.s. Check the comments for the real reason why this California woodpecker stores so much food.  Thanks to Janet Campagna for her on-the-spot report.

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Sep 24 2014

Local And Vocal

Carolina chickadee (photo by Cris Hamilton)

Chickadees don’t migrate(*) but they’re a big help when you’re looking for migrating songbirds in late September.

Waves of warblers are still passing through Pennsylvania but they’re usually silent and hidden by leaves so you probably won’t see them … unless you listen for chickadees.

Black-capped and Carolina chickadees are vocal experts on the local scene.  They know the best places to find food and where the predators lurk.  And they’re such chatterboxes!  Visiting migrants clue into chickadee locations and often stay with them in mixed flocks.

At this time of year don’t ignore the local, vocal birds.  They may have visitors with them.

 

(photo by Cris Hamilton)

(* Well, I’ve since heard that some chickadees do go places … but others stay behind.)

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Sep 12 2014

How Quickly Can You Pass These Tests?

This is a test.  For the next 3+ minutes wild New Caledonian crows will solve six physics problems in water displacement.

What will raise the floating treat?  If there are two treats which method is fastest?  The challenges are:

  1. Sand versus Water:  Will the crow know that there’s no point in dropping stones onto sand?
  2. Light versus Heavy objects:  Do heavy objects work better than light ones?
  3. Solid versus Hollow objects: Do solid objects work better than hollow ones even though the hollow objects weigh the same?
  4. Narrow water column versus Wide:  Which column takes longer to elevate?
  5. High versus Low water:  Is it faster to get the treat when the water is already close to the top?
  6. U-tube with a hidden connection:  Very hard! Will the crow figure out that one of the wide tubes governs the water level in the narrow one?

In the video the crows solve every problem but behind the scenes they faltered on the U-tube test so the scientists say they flunked it.

How quickly can you solve these physics problems?  Be quick on the U-tube test or else …

This experiment was tried with New Caledonian crows, Eurasian jays, and human children.  Read all about it here in PLOS One.

My favorite quote from the Discussion is: “The results from the current U-tube experiment suggest that New Caledonian crows are comparable to Eurasian jays, but differ from human children.”   ;)

 

(video from PLOS Media on YouTube)

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Sep 01 2014

For All The Working Birds

Harris' Hawk working as a falconer's bird in Spain (photo by Manuel González Olaechea y Franco via Wikimedia Commons)

Some birds work for a living just like we do. This Harris hawk hunts for a falconer in Spain.

This year’s most famous working bird is Rufus the Hawk who patrols Wimbledon to scare away pigeons.  Click here for the beautiful Stella Artois commercial in which he stars.

Today humans get a day off in the U.S.

Happy Labor Day.

 

(Harris Hawk working as a falconer’s bird at Alcalá de Henares, Spain. Photo by Manuel González Olaechea y Franco via Wikimedia Commons. Click on the image to see the original)

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Aug 15 2014

Raging Chickens

Lest we think that peregrines are the only birds that fight, take a look at this slow motion video of dueling sharp-tailed grouse from Cornell Lab of Ornithology.

Though they don’t have meat-tearing beaks and sharp talons these grouse are doing some damage to each other.

You won’t see this in August, even if you’re at the northern grasslands they call home.  Fighting is an activity that sharp-tailed grouse reserve for springtime courtship.  The males gather at the lek (courtship stomping grounds) and mix it up to prove who’s best.

Click here for a larger view of the video.

 

(video from Cornell Lab of Ornithology on YouTube)

 

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Aug 14 2014

TBT: Spunky

House Sparrow at Schenley Plaza (photo by Kate St. John)

Throw Back Thursday (TBT):

By August Pittsburgh’s house sparrow flocks have grown substantially and the birds are bold.  At Schenley Plaza they ask for handouts.

Click here for my encounter with a spunky sparrow in August 2008.   They’re up to the same tricks this week.

 

(photo by Kate St. John)

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Jul 31 2014

TBT: How Cowbirds Know They Are Cowbirds

Immaure brown-headed cowbird (photo from Wikimedia Commons)

On Throw Back Thursday (TBT)…

At this time of year most birds have stopped breeding and are starting to flock for the coming winter.  Many of us have noticed grackle flocks and soon, I’m sure, we’ll see flocks of brown-headed cowbirds.

The fact that young cowbirds flock with each other is a miracle in itself.  Every one of them was dumped as an egg in another species’ nest where they out-competed their foster parents’ young.   Imprinting behavior says they ought to think they’re members of the foster species, but they don’t.

How do cowbirds know they are cowbirds?  Click here to find out in this Throw Back Thursday article.

 

(photo of an immature brown-headed cowbird by Cephas at Wikimedia Commons.  Click on the image to see the original)

 

 

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