Archive for the 'Bird Behavior' Category

Aug 18 2015

Small and Belligerent

Male ruby-throated hummingbird in bander's hand (photo by Kate St.John)

Male ruby-throated hummingbird in bander’s hand (bander Bob Mulvihill, photo by Kate St.John)

Now that the breeding season is over and dry weather is suppressing native flowers, ruby-throated hummingbirds are swarming to backyard feeders in Pennsylvania.  All of them are small and feisty, but did you know the males are even smaller and more belligerent than the females?

Ruby-throated hummingbirds are sexually dimorphic in size though they’re all so tiny that only a bander could know.  At banding, birds are weighed and measured and so we’ve learned that male ruby-throats are about 87% the size of females in wing length and weight(*).  Their size is related to their lifestyle.

Female ruby-throated hummingbird in bander's hand (photo by Kate St.John)

Female (or is this an immature?) ruby-throated hummingbird in bander’s hand (bander Bob Mulvihill, photo by Kate St.John)

Male hummingbirds are the original deadbeat dads.  Ruby-throated males rush north in the spring to claim territories with lots of food which they vigorously defend with aerial displays, chasing, and bill-to-bill sword battles.

When a female shows up the male doesn’t welcome her at first (he acts annoyed) but he switches to intensive courtship displays when she perches.  Good hovering technique really impresses her and to do it well he needs lots of energy, smaller wings, and a lighter body than hers — which he has.

As soon as he’s mated with one lady he looks for the next.  He never helps with nesting and young and is so focused on attracting another female and warding off other males that he may forego feeding for much of the day.  Banders have found that adult males lose weight in June and July, though they regain it in August.

By the end of the breeding season there are noticeably fewer adult males than females at bird banding stations.  In a study done at Powdermill Nature Reserve, Bob Mulvihill and Bob Leberman found that the adult sex ratio is most skewed in the fall when there are 4.1 adult females for every 1 adult male.

Their paper(*), published in The Condor in 1992, describes why more adult males die in the summer than at other times of year:

“As a species, the Ruby-throated Hummingbird is near the extreme of small size that is physiologically possible for an endothermic vertebrate. It is conceivable that males approach a critical body mass during the summer.  Below this critical mass they may have to abandon nocturnal homeothermy for hypothermic torpor, and may starve overnight or during periods of inclement weather.”

Male ruby-throated hummingbirds are so small and belligerent that it shortens their lives.

 

(photos taken at the Neighborhood Nestwatch bird banding at Marcy & Dan Cunkelman’s by Kate St. John, 18 July 2015.  Bob Mulvihill is the bander holding the birds.)
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(*) The paper by Robert S. Mulvihill and Robert C. Leberman is entitled A Possible Relationship Between Reversed Sexual Size Dimorphism and Reduced Male Survivorship in the Ruby-throated Hummingbird, published in The Condor 94: 480-489.  It’s available as a PDF here at Sora.  Their work is cited in the ruby-throated hummingbird account at Cornell’s Birds of North America.

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Aug 13 2015

TBT: Talking Turkey

Wild Turkey baby (photo by Tim Vechter)

Throw Back Thursday (TBT):

Speaking of wild turkeys, as I did on Tuesday, here’s more about on their family life and a cute baby picture in this post from August 2008 –>  Talking Turkey.

 

(photo by Tim Vechter)

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Aug 11 2015

Lost Turkeys

Wild turkey calling (photo from Wikimedia Commons)

Wild turkey calling (photo from Wikimedia Commons)

In mid July, Mary Ann Pike had an unusual experience with wild turkeys in her back yard in Washington County, PA.  She wrote:

We have had a flock of turkeys wandering around our property for a week or two. I’ve usually seen 3 hens and 6 chicks, although my daughter says she’s seen twice that many. Last night my husband went out on the porch to start the grill for dinner and his sudden appearance scattered the flock into the woods. Suddenly, the air was filled with this sound:

http://www.dnr.sc.gov/wildlife/turkey/sound/Kee_Kee_Run.mp3

The South Carolina DNR web site refers to it as Kee Kee, the call of lost young turkeys. It was incredibly loud, and it sounded like there were 20 of them in the woods less than 100 feet behind our house, but it was probably only 6 or 8 of them. We have never heard anything like it.

Click on Mary Ann’s link and you’ll hear the sound of lost turkeys.   Did you know their calls change as the birds get older?

Baby turkeys are precocial when they hatch so as a safety mechanism they imprint on the first thing they see — their mother — and listen for her instructions.  As the family forages together they use sound to keep in touch and announce danger.

At first the babies make peeping sounds but by seven weeks of age the peep becomes a whistle which they use to make contact after being scattered by a predator.  Later the whistle drops in pitch (the kee-kee-kee call) and later still they add a yelp (kee-kee-run call).  Adult turkeys drop the kee and merely yelp to assemble the flock.

If you hear the kee-kee calls in summer, chances are it’s some lost young turkeys calling their mother.  But be careful if you hear it in Pennsylvania in May or November.  Those months are turkey season when hunters use turkey calls to attract their prey.

 

p.s. Check the PA Game Commission website for exact turkey season dates by region.

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

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Jul 24 2015

Learn About Burrowing Owls

This week a cute video of burrowing owls in Florida went viral on the web and prompted some questions about these adorable raptors.

Where do burrowing owls live?  What do they eat?  Was the Florida video taken in the wild?

Burrowing owls (Athene cunicularia) range from North to South America in dry, open areas with short vegetation and no trees.  In the U.S. they live year-round in Florida, the Southwest and California and breed in the Western dry plains and high plateau.

These owls need wide open spaces but are not picky about humans nearby.  They’ll happily dig or take over an existing burrow in remote locations as well as parks, vacant lots, pastures and campuses (Florida Atlantic University).  So yes, that video in Florida with people in the background was taken in the wild.

Burrowing owls eat insects, rodents, snakes and whatever they can catch, but they are small so they are wary.  They look cute when they stand tall but they’re actually watching for large raptors and mammals that might eat them.

How small are they?  The video above shows a research project last summer at Boise State University in which the students learn to hold, measure and band the owls.  What a privilege to learn about burrowing owls up close!

Don’t miss the end of the video when the owlets are released near their burrow.  Yes, they really are cute.

 

p.s.  Click here if you haven’t seen the Florida video.

(YouTube video from Boise State University, Boise, Idaho)

 

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Jul 17 2015

Repeat Offender

Published by under Bird Behavior

We’ve seen gulls stealing food outdoors but this bird went to the store.

Back in 2007 a herring gull became famous for repeatedly walking into a shop in Aberdeen, Scotland and stealing bags of Doritos from the lowest shelf by the door.

Eventually he became a celebrity on the nightly news and earned the nickname Sam.

When store management told the staff to close the door to stop Sam’s shoplifting, customers donated money to pay for Sam’s habit.

Sam remained a repeat offender.

 

(video from YouTube)

p.s. In Scotland the chips are called “crisps.”

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Jul 13 2015

Father-Daughter Pair in Norfolk

'Dad' and 'tHE Missus', Norfolk, Virginia (photos by Mike Inman, used by permission)

‘Dad’ and his mate ‘HE’ in Norfolk, Virginia, 2015 (photos by Mike Inman used by permission)

In a recent Peregrine FAQ I described how peregrine falcons are not social creatures like we are.  In fact most raptors don’t hang out with their relatives, so that siblings from different years and birds separated by more than one generation can’t know that they’re related.

Since they don’t know their relatives, how do raptors avoid interbreeding?  By traveling.

Young raptors naturally disperse far from home and females typically travel twice as far as males, thereby mixing the gene pool.  Here’s how far some of Pittsburgh’s peregrines traveled from where they were born:

  • Downtown Pittsburgh: Louie dispersed 2.3 miles, Dori traveled 93 miles from Akron, Ohio
  • Cathedral of Learning: E2 dispersed 2.3 miles, Dorothy traveled 450 miles from Milwaukee, Wisconsin
  • Neville Island I-79: Beau dispersed 10.7 miles, Magnum traveled 79 miles from Canton, Ohio

Bald eagles are much more social than peregrines. They fish and roost together in early winter but when it comes time to breed they disperse far and wide.  Close interbreeding among bald eagles is rare.

That’s why it was such a surprise to discover that this year’s pair nesting near Norfolk Botanical Garden is father and daughter.

The male is not banded but he has a unique tiny black dot in his left iris, called an inclusion, that’s visible in good photographs. This identified him as the 25-year-old male that used to nest in the Garden.

His mate is banded with the code “HE,” a band she received six years ago when she was a nestling at Norfolk Botanical Garden.  Yes, she’s his daughter.

Their close relationship was reported this spring by the Center for Conservation Biology (CCB) that monitors bald eagles in Virginia and banded “HE” in 2009.   CCB’s blog article provides details and photos.

It’s unusual for a female to settle so close to her birthplace but this location has had many challenges.  After the old female was killed by an airplane at nearby Norfolk International Airport in 2011, eagles were no longer allowed to nest at the Garden.  The male and all his potential mates were harassed away.  Nine nests were destroyed.  All the females left. The male didn’t nest for three years.  (Click here for the story.)

Unusual as this pairing is, the good news is that he finally found a mate, they found a safe place to nest, and together they fledged one eaglet on May 29.

It all worked out in the end.

 

(photos of the NBG pair courtesy of Mike Inman, inmansimages.com)

p.s. As part of their monitoring efforts CCB recently identified a female bald eagle with an unusual story. Click here to read about ‘Dolly’, born at the Birmingham (Alabama) Zoo to injured, unreleasable parents, she now nests along the James River in Virginia.

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Jun 26 2015

Not Exactly Squirrel Proof

Published by under Bird Behavior,Mammals

Red-bellied woodpecker and chipmunk at squirrel-proof bird feeder (photo by Jonathan Nadle)

Red-bellied woodpecker and chipmunk dining at a squirrel proof feeder (photo by Jonathan Nadle)

Jonathan Nadle’s neighbor has a squirrel proof bird feeder but it doesn’t keep out all the squirrels.

A small member of the Sciuridae (squirrel) family squeezes though the mesh and helps himself to seeds.

A lot of birds won’t visit while the chipmunk’s there — did you know chipmunks eat bird eggs? — but the red-bellied woodpecker has nothing to fear. His long sharp bill is a formidable weapon.

Red-bellied woodpecker and chipmunk coexist at the squirrel-proof bird feeder (photo by Jonathan Nadle)

(photo by Jonathan Nadle)

“Squirrel proof” might not work for chipmunks but at least it keeps out Pennsylvania’s largest member of the squirrel family –> groundhogs.

 

(photos by Jonathan Nadle)

p.s. Gray squirrels are in the Sciurinae (tree-based) subfamily. Groundhogs and chipmunks are both in the Xerinae (ground-based) subfamily and members of the Marmotini tribe (marmots!).

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Jun 19 2015

Recognize Individual Song Sparrows

Song sparrow at Schenley Plaza, 2013 (photo by Peter Bell)

Song sparrow at Schenley Plaza (photo by Peter Bell)

Believe it or not with practice you can recognize individual song sparrows by voice.

I learned this when I read about the pioneering work of Margaret Morse Nice in Columbus, Ohio.  In 1928 she began an eight year study of song sparrows at her home along the Olentangy River.  Her Studies in the life history of the Song Sparrow changed the course of American ornithology.

Margaret Morse Nice banded the song sparrows and made meticulous observations of their behavior.  She listened carefully to their songs and wrote down the variations including the phrases they borrowed from neighbors.

Her research spawned many studies of song development. We now know that: Songbirds learn their songs by listening when they are adolescents, practicing phrases, and eventually mastering their species song.  Each bird then improvises to make the song his own.  The males work hard to be skilled and unique singers because the females are attracted by the best courtship songs.

I wondered if I could recognize an individual’s song so I started at home.

My backyard is the territory of a male song sparrow whose tune I hear every morning.  Eventually I learned his morning song(*). If I could write musical notation I’d put it here.

From my front porch I can hear “my” song sparrow and my neighbor’s front yard sparrow counter-singing to maintain their territories.  I know those two don’t sound the same.

I can’t identify more than one tune yet but I can recognize “my” song sparrow in the morning now.

Try it and see.

 

(photo by Peter Bell)

(*) Dr. Tony Bledsoe says that each song sparrow may have up to five distinct songs.  So though I’ve learned the “Good morning” tune I’ve got a lot more learning to do!

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Jun 18 2015

TBT: Food For Thought

Gray squirrel (photo by Chuck Tague)

Gray squirrel (photo by Chuck Tague)

Why are songbirds angry at squirrels?

On Throw Back Thursday (TBT), here’s some Food For Thought from June 2008.

 

(photo by Chuck Tague)

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Jun 05 2015

How To Find A Raptor

Red-tailed hawk mobbed by crows (photo by Dori via Wikimedia Commons)

Red-tailed hawk chased by crows (photo by Dori via Wikimedia Commons)

Are you looking for a hawk, an owl, or a fledgling raptor?  Have you seen a juvenile peregrine fly around the corner but now that you’ve made that walk (or run!) you can’t find him?

Stop, listen, and watch for other birds.  They’ll tell you where he is.

Small birds sound the alarm when a bird of prey is near.  In the breeding season they surround and mob the raptor if they think they can get away with it.  They’re trying to drive the raptor away from their nests.

Robins are my favorite hawk-alarms because they’re so loud and persistent.  Other species join them and they all get louder and louder.  When the crows show up it becomes a chase.

So if you need to find a raptor (at a Fledge Watch, for instance) listen for the smaller birds, look where they’re looking and you may find the raptor — though perhaps not the one you’re looking for.

 

(photo by Dori via Wikimedia Commons. Click on the image to see the original)

p.s. American robins’s eyes look sideways, not straight on like ours, so you’ll have to pick one side of the head and follow the sight-line from there.  Confusing!

p.p.s.  Mark your calendars for Downtown Pittsburgh Fledge Watch, June 13-20, daylight hours.  Announcements and instructions will roll out in the next several days.  Stay tuned at Outside My Window. Check the Events page for updates.

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