Outside My Window

Yellow-billed cuckoos are usually hard to find.  They skulk in the treetops – like this one is doing – and are found only by the sound of their amazing voices. 

That’s why I was surprised to see three cuckoos in the open recently.  Two were singing and chasing while a third one watched.  Was this territorial behavior?  Courtship?  In July?  I decided to find out.

Yellow-billed cuckoos return to our area in April and May but they tend to nest from late June to July because they wait for an abundance of their favorite foods: caterpillars and cicadas.  In my experience this gives cuckoos extra time to be secretive while other birds are visibly courting and nesting.

Cuckoos may be secretive but they’re more versatile when they nest, choosing among three methods depending their food supply. 

In years of normal or low food abundance, yellow-billed cuckoo pairs go the traditional route of building and using their own nests, but in years of explosive caterpillar or cicada infestations – such as 17-year cicadas – female cuckoos produce extra eggs, and they need to put them somewhere. 

Sometimes they breed co-operatively.  Two females share the same nest with a male and all three of them tend the young.  The males handle overnight incubation so I think the “co-op” guys must struggle to cover 5-11 eggs instead of the usual 2-3.

Alternatively, the females lay eggs in other birds’ nests, choosing those whose eggs are the same blueish-green color as their own.  According to BNA Online, yellow-billed and black-billed cuckoos are “the only known facultative, interspecific brood parasites among altricial birds.”  “Facultative” means that they can but don’t always do this, so cuckoos don’t have the bad reputation the brown-headed cowbird has.

Yellow-billed cuckoos have one more surprise up their sleeves.  When their nestlings are about six days old they become fully feathered in only two hours.  Their feathers literally burst from the feather sheaths.  Imagine Mrs. Robin’s shock when one of her kids goes from bare down to flight feathers so fast.   Surprise!  That one’s a cuckoo.

Now that’s versatile.

(photo by Chuck Tague)

p.s.  Based on the lateness of the cicadas this year, this is probably a low-food-supply year for cuckoos.

It’s not fall but I’ve been seeing a fall phenomenon:  large flocks of grackles.  These are not the huge November flocks that number in the hundreds but they’re larger than family groups.

At dusk they gather at the Monongahela River near Greenfield.  At dawn they fly east over my house making flight calls, a soft chucking sound.

Sometimes they land in my yard, graze on fallen seed, and play in the bird bath.  That’s when I discover the flocks are made up entirely of immature common grackles and starlings.  I can tell by their colors.  The gang wears brown.

Juvenile common grackles have brown feathers, brown eyes, brown legs and brown beaks.  They lack the iridescent feathers of their parents whose yellow eyes and black beaks and legs make them stand out.  Juvenile European starlings are also basic brown without the oily sheen of the adults.  They too have brown beaks and sometimes a dark eye line.

But the juveniles are molting.  I can see new, starry feathers on the starlings and the beginnings of iridescence on the grackles.  Soon the juveniles will resemble the adults.

Who knows when the adults will join these flocks.  In August?  September?  Will I be able to tell the difference when the young resemble their parents?  I don’t know.

For now it’s just a gang of teenagers.

(photo by Chuck Tague)

Golden-winged warblers are declining throughout their range, due in part to competition with blue-winged warblers and in part to habitat loss.

This week The Allegheny Front highlights a study in Pennsylvania which hopes to increase golden-winged warbler breeding habitat and halt their decline. 

Click here to listen to the show.

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(painting by Louis Agassiz Fuertes, from WikiMedia, in the public domain in the U.S.)

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Yellow warblers are in Pennsylvania only 10 weeks and in that time they claim territory, build a nest, lay eggs, incubate, hatch eggs, feed young, guide their young to independence and begin to molt.  And now in mid-July they’re leaving for home.

A yellow warbler’s annual time budget is amazing.  Six months of the year, from October through March, these tiny yellow birds live in Central and South America, as far north as the Yucatan, as far south as Amazonian Brazil, Bolivia and central Peru.  They spend four months of the year migrating – about two months each way – and only about two months on their breeding grounds in North America from Alaska to North Carolina.  No wonder their breeding season is frantic!

The females are the ones on a tight schedule.  The males arrive at the breeding grounds 10 days ahead of the ladies and spend that time staking out their territories.  When the ladies arrive they find a mate within one day of arrival.  Imagine choosing that fast! 

I think they have no time to be picky.  The females do all the early work alone.  They build the nest, lay the eggs and do all the incubation.  By the time the females have been on their breeding grounds for 24 days they have nestlings begging for food.  Both parents feed the babies and in 8-10 more days the young have fledged. 

Cowbirds cause delays.  If a cowbird lays an egg in a yellow warbler’s nest, the female warbler recognizes the problem and builds a new nest on top of the old one, burying the cowbird egg so that she can start over.  Other than that she’s in a rush. 

Right now she and her mate are getting the kids ready and packing to leave (figuratively speaking).  Yellow warbler fall migration peaks around July 31 at Presque Isle State Park, even earlier at Powdermill. 

This is a bird in a hurry to get home.

(photo by Chuck Tague)

Look closely under this mother’s breast feathers and you’ll see two babies, one of whom is yawning.

This common nighthawk is nesting on a roof and was found by Paul Leverington who owns a roofing business in Euclid, Ohio.  He’s also a fine photographer. 

Last month I wrote about the decline of common nighthawks, so I know how lucky Paul was to see one nesting.  A rare sight indeed!

(photo by Paul Leverington)

Poor Mama Bluebird!  Which mouth should she feed?  No matter which one she picks the other two will still be begging.

Despite appearances, having three fledged babies is a great sign of success.  As I’ve learned from watching robin nests it’s a huge challenge to get a baby bird to this stage.

People who tend bluebird boxes know exactly what I mean.  At the start of the season there’s the threat of cold, wet weather that suppresses their food supply (insects) and causes the babies to starve.  Then there are blowflies and other nasty parasites who kill the young.  Snakes, raccoons and cats take their toll, and bluebirds, like tree swallows, face competition for nest sites.  Since they’re the least aggressive of the cavity nesters, bluebirds take it on the chin.  The worst are the house sparrows who claim all the nest sites in their territory and kill bluebird adults and young, even in boxes the sparrows don’t intend to use.

Fortunately for bluebirds, people watch out for them and help by removing whatever threats we can.  It’s a symbiotic relationship in which bluebirds nest successfully and we get the enjoyment of watching a very sweet and beautiful bird. 

If your neighborhood doesn’t have open fields to support nesting bluebirds, you can now watch them nesting online.  Check out the PA Game Commission’s bluebird nest box camera at their Harrisburg Headquarters.  You won’t see this fledgling activity but you’ll get a glimpse inside the box. 

So congratulations, Mama Bluebird!  Soon your babies will be on their own.  Whew!

(photo by Kim Steininger)

True to their name, tree swallows nest in hollow trees – or in the next best thing, bluebird boxes.

When they arrive in early spring, their first and most important activity is to find a nest hole.  Suitable nest sites are scarce, so tree swallows are aggressive about claiming them and will fight – even kill – another tree swallow of the same sex who dares to claim their nest hole.  At this stage it can get gruesome.  If a site has nestlings and the male dies, the new male may kill the widow’s young.  Females have been known to kill the young of others to make the site become available.  So much drama!

But there are other challengers who want nest holes.  House wrens, house sparrows and northern flickers will destroy tree swallow eggs and nestlings if they can.  Eastern bluebirds also want nest holes but they get along with tree swallows if two boxes are provided near each other, one for each species. 

Aside from nest site competition, tree swallows are very social creatures and tend to nest near each other if enough sites exist.  Once a site is selected the female builds a nest inside it and adorns it with feathers.  Even if she arrived weeks earlier, she waits to lay her eggs in May so the babies will hatch around June 1.  Both parents feed the young, making 10-20 trips per hour to keep those yellow mouths filled! 

Now it’s July and all the tree swallows are about to fledge.  Next month they’ll be on the move in large flocks, headed for Florida and the Gulf of Mexico. 

Watch them while you can.

(photo by Kim Steininger)

Last week I discovered an American robin nest outside my study window. 

As I sit here and type, Mother Robin is making food deliveries to her tiny babies who are slightly older than the chicks pictured here.  This is probably her second brood this season.  If her first nest was very early or if it failed, this could be her third.

Now she pauses to brood her babies.  As she sits on the nest she makes a high-pitched “eeeeeeeeep” sound.  It’s a sound I wouldn’t associate with robins if I hadn’t seen one making it.  Is she calling her mate? 

Her chicks are silent, a good defense against predators at this age.  Even so, Mother Robin is wary.  My cat sits at the window as I blog and the robin is alert to Emmy’s pointy ears.  I don’t think Emmy’s noticed the robin’s nest because it’s far away and hidden by leaves.  (I use binoculars to see the babies.)  My cat is much more absorbed by the house sparrows sitting on the wire shouting at her. 

I hope all goes well for this robin family.  There are crows, grackles and blue jays on my street who would love to raid her nest.  Good luck, babies.

(photo by Chuck Tague)

For me the common nighthawk is an iconic species.  Its diving courtship display so fascinated me as a ten-year-old that I developed a lifelong interest in birds.

Nighthawks used to be easy to find in my Pittsburgh neighborhood in summertime. I live across the street from a floodlit ballpark where I could watch them hawking insects at dusk in the bright ballpark lights.

But not anymore.  Common nighthawks have declined precipitously in Pittsburgh and the eastern United States, so much so that some states list them as an endangered species.

Common nighthawks are not hawks but nightjars, relatives of the whip-poor-will, whose diet consists solely of flying insects including mosquitoes, moths and flying ants.  They’re incapable of torpor and must eat hundreds of insects per night so they require warm weather and plentiful bugs. 

Nighthawks range widely in the Western Hemisphere migrating from Argentina to Canada.  They used to arrive in Pittsburgh around May 5 and leave by September 5.  During fall migration hundreds of birds would pass through at dusk for two weeks starting at the end of August. 

Surprisingly, common nighthawks have not been well studied, though new efforts are underway.  What is known is that in the northeastern U.S. they used to nest in natural areas.  Then in the 1890s they began to nest almost exclusively on gravel rooftops in cities and towns.  In the 1990s people replaced gravel roofs with rubber roofs and nesting opportunities disappeared.  Meanwhile something must have gone wrong at their wintering grounds or in migration (probably pesticides) because year after year fewer migrants leave in the fall and even fewer return in the spring.

Ten years ago there were several nesting pairs in my neighborhood but last summer there was only a lone individual calling for a mate who never came.  This year he called for two weeks and was gone.  I don’t think I’ll ever again see them nest in my neighborhood.

Considering their rapid decline, I may live to see common nighthawks go extinct east of the Mississippi just as peregrine falcons did when I was young.

With human help peregrines came back.  Can we save the nighthawk?

(photo from WikiMedia taken by Daniel Berganza near Miami, Florida.  Click the photo to see the original.)

If you’ve never seen one I’m sure you’re wondering… what the heck is this? 

It’s a Baltimore oriole’s nest, a bag of birds. 

If you look closely at the top of the nest you can see the tail and wing of the adult male.  His head and feet are inside the bag but his tail doesn’t fit.

Despite the leaf cover, these bags are noticable in western Pennsylvania right now because the baby birds are making a lot of noise inside.

Baltimore orioles are nothing if not noisy.  Only eight weeks ago the males came back to Pennsylvania, singing and chattering and claiming territory.  Soon the ladies arrived and the males displayed their beautiful orange feathers and made a lot of noise to attract their attention.  The females are impressed by this – and they’re noisy in return.  After they’ve chosen a mate, Baltimore oriole pairs stay in constant audio contact. 

Shortly after pairing up, the female Baltimore oriole builds her nest at the tip of a drooping tree branch.  It takes 5-8 days of weaving plant fibers, string, grape bark, grasses and pieces of old oriole nests to make this bag.  She doesn’t engage in skillful weaving but her random method works nonetheless. 

When she’s completed a hanging structure she lines it with feathers, soft grasses, wool, willow and dandelion fluff.  Her mate sings while she builds and she replies.  She then lays 4-6 eggs and incubates them alone for 12-14 days.  Her mate’s contribution is to sing nearby.  Lots of noise.

When the eggs hatch both parents feed the babies.  After about a week the nestlings take over in the noise department and become very vocal inside the bag.  I found three oriole nests at Schenley Park last week just by following the babies’ sound.  It’s usually a disadvantage for baby birds to give away their location but Baltimore orioles have always been noisy and it doesn’t seem to have to damaged their chance at survival.

As the nestlings get noisier their father sings less.  In 12-14 days they fledge and both parents feed them for about a week.  Then mom begins to molt and travels more widely.  Dad coaches the fledglings for a couple of weeks, then the youngsters disperse.  He stays on territory until he’s finished molting and leaves our area in late summer.

It all happens very fast.  From late April to mid-July there’s a lot of activity and then it’s over.  

Now’s the time to look for a noisy bag o’ birds.

(photo by Chuck Tague)