Archive for the 'Bird Behavior' Category

Dec 16 2014

Socially Isolated? Age Faster

African grey parrot (photo by Keith Allison from Wikimedia Commons)

Early this month I wrote how lobsters don’t age because they have telomerase that repairs the DNA sequences at the ends of their chromosomes (telomeres).   Most adult organisms don’t have that advantage so every time our cells divide our telomeres get shorter.  This ages our cells and ages us.

African grey parrots are highly social creatures who are often stressed when they live alone.  It turns out that loneliness affects their telomeres.

In a study published last spring in PLOS ONE, scientists at the University of Veterinary Medicine at Vienna, Austria examined blood samples from captive African grey parrots and compared the telomeres of parrots who lived alone versus those who lived with a companion parrot. (*)

Despite being the same age, solo African grey parrots had noticeably shorter telomeres than those who lived with friends.  The solo parrots aged faster than their peers.

Not only did the study illuminate the sadness of single parrots but it suggests that “telomeres may provide a biomarker for assessing exposure to social stress.”

Read more here in Science Daily.

Humans are social creatures, too.  Doctors and nurses know that isolated humans don’t heal as fast or live as long, so when you’re sick it helps to have the care of those who love you … which leads me to an update on my husband’s recovery (see this blog post for news of his accident).

Today it’s been three weeks since Rick was hit by a car in a crosswalk.  He’s making progress though there are setbacks, such as the operation to fix his broken nose.  Fortunately his friends and relatives have rallied to help him (and me).  Rick is a very social creature — more social than I am — so calls and visits from his sister and friends have raised his spirits.

For now my life is circumscribed by his needs and appointments.  I miss birding and hiking alone (I’m not as social as Rick) but I try to go outdoors every day because that’s what keeps me sane.

We are hoping for good long telomeres when this is over.  ;)

 

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

(*) The parrot news release notes that in Austria it’s illegal to keep a parrot in isolation from other parrots, though some people do.

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Dec 15 2014

Can’t Tell Their Sex By Their Color

White-throated sparrow, white-striped color morph (photo from Wikimedia Commons, Creative Commons license)

White-throated sparrow, white-striped color morph (photo from Wikimedia Commons)

Many birds are sexually dimorphic — males are more colorful, the females are drab — but this isn’t true of white-throated sparrows.

White-throated sparrows come in two color morphs: white-striped shown above, tan-striped below.  The crisp white-striped birds aren’t always male, the plain tan-striped birds aren’t always female.  You can’t tell their sex by color.

White-throated sparrow, tan-striped color morph (photo by Henry McLin on Flickr, Creative Commons license)

White-throated sparrow, tan-striped color morph (photo by Henry McLin, Flickr Creative Commons license)

Here they are side-by-side: white-striped on left, tan-striped on right.  Notice that …

White-throated sparrows -- white-striped and tan-striped side-by-side (photos from Wikimedia Commons and Henry McLin, Creative Commons licenses)

  • Head stripes are black-and-white versus brown-and-tan
  • Lores are bright yellow versus dull yellow
  • Malar stripe is weak versus prominent
  • Breast is gray versus brown-and-tan
  • Breast is mostly clear versus very streaky

Not only do they look different but the white-striped birds are aggressive, philandering and don’t take much care of their kids while the tan-striped birds are gentle and very caring of their young.

You would think these differences would force one of the color morphs to disappear from the gene pool but it doesn’t.  The reason is surprising.

When it comes to picking mates, these birds always mix it up.  White-striped (aggressive) males mate with tan-striped (care-giving) females and the tan-striped (gentle) males mate with white-striped (philandering) females. Thus the color morphs and personalities persist.

Learn more about their amazing social behavior in this article by GrrlScientist in The Guardian, May 2011.

And when you see white-throated sparrows you’ll know you can’t tell their sex by their color but the drab ones are always good parents.

 

(photos: White morph white-throated sparrow from Wikimedia Commons, Creative Commons license.  Tan morph by Henry McLin on Flickr, Creative Commons license.  Click on each photo to see its original)

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Nov 26 2014

On Keeping Peacocks

Published by under Bird Behavior

Peacock, Pavo cristatus, in Venezuela (photo in the public domain by Wilfredor via Wikimedia Commons)

Recently I read Flannery O’Connor’s (1925-1964) essay about peacocks, “The King of the Birds.”  She wrote it when she had 40 peafowl though she admitted she’d stopped counting and really had no idea how many there were.

Apparently peafowl are addictive.  You can’t keep only one — a single bird is lonely — so you start with a pair (male and female) but these two make more and if you haven’t planned for offloading the peachicks you end up with ummmmm … “40.”

Though not affectionate Indian blue peafowl (Pavo cristatus) are breathtaking to watch.  During the breeding season the males display majestically for almost any reason.  (They also fight.)  The only creatures indifferent to their beautiful tails are the peahens.  “Ho Hum,” she says.  “I’ve seen that before.”

Those who keep peafowl know they need space — lots of space — because they’re loud and because they roam.  They’ll eat anything, especially the neighbors’ flowers, fruits and vegetables.  In spring and summer the males shout like this.  If you’re not a peacock addict, the sound can get on your nerves.

Though peafowl spend all day on the ground, they roost in tall trees at night just like wild turkeys.  When peacocks run away from home, they hang out with wild turkeys.

Imagine finding peacocks in the woods!

 

(photo in the public domain via Wikimedia Commons. Click on the image to see the original)

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Nov 21 2014

Birds That Count

Published by under Bird Behavior

NYT ScienceTake screenshot: How Birds Count

We know that crows and parrots can count … but robins?

Alexis Garland at Victoria University of Wellington ran tests using a special bird feeder to see if wild New Zealand robins can count.

Click on the ScienceTake screenshot to see them do it.

 

 

(screenshot from New York Times video, ScienceTake: How Birds Count.)

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Nov 04 2014

How Starlings Stick Together

Watch this video of a starling flock evading a peregrine falcon in Torino, Italy and you’ll see some truly amazing coordinated flying.

How do starlings wheel and turn in such tight balls?  How do they compress and expand without hitting each other?  The mystery has puzzled humans since the first time we saw it and recent explanations that each bird keyed only on his nearest wing-neighbors did not seem to answer the problem.

Now a study published in July in the Proceedings of the National Academy of Sciences explains their behavior in an elegant model.

Using agent based modeling of self-propelled particles researchers from the University of Warwick’s Department of Physics created a simulation that behaves just like a starling flock attacked by a hawk.

Their video below plays the simulation twice.  Isn’t it uncanny how much this matches what the flock is doing above?

Changing patterns of light and dark within the flock are the key to each bird’s movement.  They all want to be near each other but they need to see what they’re doing.  The team writes, “We show that large flocks self-organize to the maximum density at which a typical individual still can see out of the flock in many directions.”

Lead researcher Daniel Pearce explains the model’s rules: “Each bird is represented by a particle which each have an identical set of rules to follow (and likelihood of making a mistake). In this case the rules are (a) follow your nearest neighbour and (b) move towards the areas of the projection containing the most information. When lots of these particles are introduced, the result is a collective motion much like that of a real flock of birds.”

What is “information” in this context?  The technical answer is “the birds fly toward the resolved vector sum of all the domain boundaries.”  Hmmmm!

Click here to read more in Science Daily.

 

(peregrine-starling video by “greenkert” on YouTube. Simulation video by Daniel Pearce on YouTube.  Information from University of Warwick, Revealed: The mystery behind starling flocks” in ScienceDaily)

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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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