Monthly Archives: May 2014

How To Build A Robin’s Nest

Mid-May is the height of robin nesting season in Pittsburgh.  The first nestlings have hatched and some are ready to fledge.

On Thursday I saw my first-of-2014 robin fledgling in Schenley Park.  Last month his mother spent 5-7 days building his nest.  This video shows her process in only 8.5 minutes.

While Mr. Robin sings in the background, his mate brings dry grass and drops it into place.  Her project looks sloppy for a while, then she does a cool thing.  She rapidly stamps her feet inside the nest while holding the edges with her wings and tail.  This makes the cup exactly fit her body.  How cool is that!

Halfway through Mr. Robin comes for a brief inspection.  Since he neither builds nor incubates, the nest is of passing interest to him.

When the cup is complete Mrs.Robin lines it with mud, then adds fine bits of dead grass to make the nest soft and lays her eggs.  (The last two steps are not in the video.)

Robins raise two or three broods per year and usually build a new nest for each brood.

What a lot of trips back and forth!

(video on YuoTube by richpin56)

Remarkable Journeys

Swainson's thrush (photo by Steve Gosser)

In the middle of May, Schenley Park’s bird population bursts at the seams as migrants stopover on their way to Canada.  Early this week one of the most numerous visitors was the Swainson’s thrush.

We tend to take their migration for granted, knowing the birds make long journeys from South to North America, but we’re unable to visualize it.  How far do they go?  How long do they live?

Last December in the Columbian highlands a bird banding station captured a previously banded Swainson’s thrush.  Its bands revealed the bird was captured more than five years earlier while on its journey north.

The thrush was banded near Unadilla, Nebraska in May 2008, heading home to breed in central Canada.  At that time it was at least one year old.  In December 2013 it was recaptured near Las Margaritas, Columbia 2,700 miles away, probably at its winter home.  It was more than six years old and had made the journey at least 13 times.

From Canada to Columbia, read about this bird’s journey and see the map at Klamath Call Note.

(photo of a Swainson’s thrush on migration in Pennsylvania by Steve Gosser)

Fun Facts About Cigars With Wings

Chimney swift flying in Austin, Texas (photo by Jim McCullough, Creative Commons license, Wikimedia Commons)
Chimney swift in flight (photo by Jim McCullough via Wikimedia Commons)

14 May 2014

Chimney swifts (Chaetura pelagica) return in April from their winter homes in South America.

In this week’s hot weather they’re zooming high above the rooftops eating insects and courting.  In flight they look like cigars with wings.  Here are some fun facts about them.

  • Chimney swifts are small. Stretch out your fingers as wide as you can. The wingspan of a chimney swift is the distance from the tip of your thumb to the tip of your pinky finger. If you have big hands, your hand is wider than the bird.
  • Chimney swifts “sing” a dry chittering song that is loudest when they’re courting.
  • Though most mating occurs at the nest chimney swifts can mate in flight!
  • Swifts cannot perch horizontally. Their legs+feet are shaped like garden claws so they can only cling upright to the inside of a chimney or hollow tree.
  • They nest in chimneys, constructing a half-moon cup of dead twigs glued with their sticky saliva.
  • To build a nest they grab dead twigs with their feet as they fly past trees, then transfer them to their bills to carry home.  I have never seen a swift gathering or carrying twigs.  It’s something to look forward to.
  • The female lays 4-5 eggs which both parents incubate for 19 days.  Because they delay incubation until the next-to-last egg, most of the eggs hatch on the same day. The young fledge at 28-30 days.
  • Sometimes one or two non-mated swifts will help a pair incubate, brood and feed their young.
  • Chimney swifts can live an amazingly long time, averaging 4.6 to 5.5 years.  Some have lived to be 15.
  • In flight they sometimes look as if their wings are out of synch, one wing up and the other down. This illusion is caused by their very rapid side-to-side turns. 

(photo by Jim McCullough, Creative Commons license on Wikimedia Commons. Click on the image to see the original)

A Last Look?

Olive-sided flycatcher (photo by Dominic Sherony via Wikimedia Commons)

On Sunday afternoon I saw an olive-sided flycatcher above the Sand Dunes Trail at Oak Openings Preserve, Swanton, Ohio.  I mention these specifics because he was only the second olive-sided flycatcher I’ve ever seen.  The first was 11 years ago at Raccoon Creek State Park on May 18, 2003.

Olive-sided flycatchers were always uncommon and now are increasingly rare.   In the past 40 years they’ve declined 3.3% per year, especially in western North America.  Where there used to be 100 individuals there are only 27 now.  They used to nest in Pennsylvania but no more.

Though he isn’t a flashy color he’s the peregrine falcon of flycatchers.  Perched high on a dead snag he scans the air for large flying insects, dives to catch them, and chases them down if they try to escape.  This bird is fast!   I watched him chase down bees or wasps, return to the perch and swallow each catch in a single gulp.  He rarely missed.  Then, just like a bird of prey, he ejected a pellet.

Olive-sided flycatchers breed at coniferous and boreal forest edges in the western U.S. and Canada and spend the winter in northwestern South America.  They happen to prefer burned or logged areas because the openings make for better flycatching.  The bird I found was in a location that had burned several years ago.

Pesticides, loss of bees and wasps, and habitat loss in North and South America have all contributed to the olive-sided flycatcher’s decline.  A reintroduction program like the one that restored the peregrine falcon can’t save this bird.   Instead we have to cooperate to preserve large tracts of his habitat.  Unfortunately, human cooperation on this scale is notoriously difficult to achieve.

This was my second look at an olive-sided flycatcher.  Will it be my last?

 

(photo by Dominic Sherony, Creative Commons license on Wikimedia Commons. Click on the image to see the original.)

Start Late, Finish Early

Gulf Tower chicks eat dinner, 6 May 2014 (photo from the National Aviary falconcam at Gulf Tower)

With two Pittsburgh raptor nests on camera we’re able to watch the nest cycle differences between peregrine falcons and bald eagles.  A big difference is timing: Peregrines nest later but they finish earlier.  We’re about to see that unfold.

Back in March it felt like peregrine egg laying was “late” because the Hays bald eagles had been incubating for two and a half weeks before Dori laid her first egg at the Gulf Tower.  In fact Dori was early, even by her own standards.  We just didn’t realize how much earlier bald eagles begin.

On May 6 (above) the peregrine nestlings were still developmentally behind the eaglets.  They weren’t very mobile and were still covered in fluffy white down with no apparent flight or facial feathers. They looked like babies.

On that same day the eaglets had been mobile for two weeks, had already grown some head and body feathers and had started to grow flight feathers.  They already looked like eagles (below).  PixController’s YouTube video of the bald eagles’ growth in April shows how they got to this stage.

Pittsburgh Hays eaglets, 6 May 2014 (photo from the Pittsburgh Hays eaglecam by PixController)

 

Despite their late start the Gulf Tower peregrine chicks are about to surpass the Hays bald eagles.  The table below shows they’ll depart their nest two+ weeks before the eaglets.  The peregrine fledglings will fly right away (departing a cliff nest requires flight) while the eaglets will likely flutter from their tree to lower vegetation or the ground where they may wait 1-3 weeks before flying again.

Keep in mind that fledge dates are just estimates.  Young birds learn to fly on their own schedule.

2014 NESTING LANDMARKS FOR THE GULF TOWER PEREGRINES AND HAYS BALD EAGLES:

____________ 1st Egg Hatch 1st Flight/Nest Departure
Gulf Peregrines 3/10 4/20-4/23 5/28-6/02 (5.5 wks)
Hays Eagles 2/20 3/28-4/02 6/16-6/28 (11-12 wks)

 

 

Start late, finish early.  Peregrines are faster than eagles in everything they do.

 

(photos from the National Aviary falconcam at Gulf Tower and the Pittsburgh Hays eaglecam via PixController)

 

The Biggest Weekend For Birds

Blue-winged warbler (photo by Shawn Collins)

This weekend is a great time to see migrating warblers. So many are on the move that you don’t have to go to a hotspot to see them.  They’re in every tree.

Blue-winged warblers prefer shrubland and old fields but during migration you might find one anywhere, even in Downtown Pittsburgh.

Don’t let his name fool you.  At first glance you may not see blue wings.  Your brain will register “yellow body, white wingbars, black eyeline.”  Are his wings blue?  Not always.  In many light conditions they look gray.  The clincher is his black eye-line — a long black line that connects his eye and beak.

You might find a blue-winged warbler near home right now.

This is the biggest weekend for birds.

 

(photo by Shawn Collins)

Which One Should I Choose?

Two male & one female brown-headed cowbirds (photo from Wikimedia Commons)

8 May 2014

Brown-headed cowbirds (Molothrus ater) are courting now because their victims are nesting.  The males sing a bubbly whistling song to attract a favored female.  After she’s chosen a mate, Mrs. Cowbird lays her eggs in the nests of smaller birds. Her victims raise her chick while their own eggs and nestlings die, partly at the hands of her aggressive cowbird chick.

Cowbirds never build nests nor do they incubate so their pair bond is cemented by courtship songs and postures.  Amazingly, the quality of the male’s song really matters.  That’s how the female decides who to accept and who to ignore.

What happens if a female can’t tell the difference between good and bad songs?  What happens within the flock when one lady doesn’t follow the rules?  Last year scientists learned that a single tone-deaf female can upset cowbird society.

Researchers at the University of Pennsylvania led by Sarah Maguire inactivated the song-control centers of some female cowbirds’ brains so they could no longer distinguish between high and low quality songs.  When placed in a mixed-sex flock these ladies reacted to all songs and did not stay with a chosen male for long.

Since male dominance among cowbirds is based on song quality the best guys usually get the best gals.  However, when a tone-deaf female appeared in the flock she listened to all males equally and the minor males got a boost.  The dominant males courted the altered female more vigorously.  The other ladies were left in the cold.

Which guy will she choose?  One tone-deaf female can mess up an entire social structure.

Read more here in PLOS One.

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

female rattle song

male song whistle, male song bubble

Reminder: BirdSafe, Monday May 12

Wood thrush rescued Downtown, 28 April 2014 (photo by Matt Webb) Join BirdSafe Pittsburgh volunteers this coming Monday May 12 at 5:30am at PPG Plaza.  Learn how to rescue injured migratory birds and tally those killed in Downtown Pittsburgh’s hall of mirrors.

Contact Matt Webb at (412)53-AVIAN (412-532-8426) or birdsafepgh@gmail.com for more information.   Click here to read more.

p.s. In just 3 days last week volunteers found and rescued wood thrushes, an ovenbird, a Kentucky Warbler, and a magnolia warbler.  Every bird counts!