Outside My Window

Sometimes you can’t see a bird’s traits until they’re frozen in a photograph.

Look closely at this American goldfinch browsing on Sam Leinhardt’s zinnias.  Even though only the top of her head is visible you can see both of her eyes. 

Goldfinches are small birds about 4.5 inches long.  At this size they are easy prey for owls, cats and hawks so they have to be wary.  What better way to be prepared than to have peripheral vision above and behind so you can see danger coming, even when your head is down feeding on seeds. 

Many small birds have this trait, but how did they get it?  Indirectly, from the relentless pressure of predators.  Goldfinches who couldn’t see danger coming were easy prey while those with wide peripheral vision survived.  The survivors had “kids” with the same trait.

So, yes, she really does have eyes in the back of her head, just like all her relatives.

(photo by Sam Leinhardt)

Are you seeing a lot of blue jays lately?  I am. 

I used to think blue jays didn’t migrate because their range map shows them as year round in North America.  Because I see them all year, I assumed I was observing the same individuals.

That was until one May morning at Lake Erie when I saw a long line of jays flying northeast along the shore.  Chuck Tague told me they were flying to Canada but the lake was a big barrier.

As we watched, the jays turned north over the lake and hit a wall of air none of us could see.   One by one they battled the invisible barrier.  Finally they broke formation and flew back over land where they regrouped and again proceeded in a line, following the shore.

Other than similar observations at migration hot spots, blue jay migration is subtle if it occurs at all.  Blue jays don’t have to leave home if they can store enough food for the winter.  When they do decide to migrate, they travel during the day in small groups of 10 to 30 birds.  It often doesn’t look like they’re migrating because the jays fly one at a time from tree to tree, a behavior that resembles foraging.

This fall blue jays are leaving Canada in droves because their winter food supply is low – too few acorns, beechnuts and hazelnuts.

I’m sure they’ll enjoy their time Pittsburgh.  We have a bumper crop of acorns.

(photo by Chuck Tague)

Yesterday morning I stepped out on the front porch just after 6:00am to check the weather.  It was my first morning home from Maine and I was a little surprised that I didn’t need a jacket and the sun hadn’t come up yet.  What was I thinking!  Maine is certainly colder and it’s so far east that the sun rises there 45 minutes earlier than it does in Pittsburgh.  I had nearly an hour to wait for dawn.

As I gazed at the waning moon I heard a sound like spring peepers coming from above.  I knew the distinct solo “peeps” were the nocturnal flight calls of migrating thrushes, but which ones?

The pre-dawn sky was clear with a light wind from the north.  The birds kept coming with hardly a pause.  I rushed indoors to get my binoculars but it was too dark to see the birds.  In my excitement I forgot to count the sounds so all I can tell you is that they passed by steadily for 20 minutes.  My guess is there were several hundred of them. 

Later indoors, I checked my birdsong CDs and the Internet for samples of nocturnal flight calls.  I couldn’t find any audio examples – only voice-prints – but I looked through descriptions of various thrushes’ calls and found this at eNature’s Sibley Guide for the Swainson’s thrush:  “Flight call a mostly clear, level, emphatic heep or queev reminiscent of Spring Peeper (treefrog) call.”

So that’s who they were. 

I heard Swainson’s thrushes migrating this morning, too.  I wish I could have seen them.

(photo by Chuck Tague)

From the moment I became a birder there was a section of the field guide that gave me the shivers.  In the Peterson Field Guide to Birds there were four pages labeled Confusing Fall Warblers. 

I studied those pages many times but it was hopeless.  The birds in the pictures were females or juveniles.  Some had wing bars, some did not.  Much as I tried I couldn’t identify those tiny, olive-green and yellow birds. 

For many years I was cowed.  Finally I bought a field guide that didn’t have those pages and solved my problem by avoiding it.

Years later I’m able to identify many fall warblers and I didn’t do it by paying attention to them.  Instead I spent May after May looking at spring warblers.  I got used to identifying the adults, noticing their body shapes, bill sizes and whether they had eye stripes, wings bars or beady eyes. 

Eventually I realized that young warblers have the same traits.  A long, thin-bodied warbler is still long and thin-bodied whether it’s young or old.  An adult warbler who feeds by poking under bark will have babies who do the same.  A warbler with a beady black eye, like this female yellow warbler, has a beady black eye at every age.

I’m still confused by most fall warblers – and a couple of spring ones too – but I enjoy them more since I gave up trying so hard.

(photo of a female yellow warbler by Chuck Tague)

The amazing thing about warblers is how short a time they’re with us. 

These prothonotary warblers were courting and planning a family when Kim Steininger snapped their picture in the Cuyahoga Valley in May.  Now they’ve finished breeding and are leaving for their wintering grounds somewhere between Veracruz and the coast of Venezuela.

So how short a time are prothonotary warblers here?  Their year is almost evenly divided into three-month periods of activity: 

• Northward migration from late February to early May,
• Breeding from May through July,
• Southward migration from August through October and
• On their wintering grounds from November through January. 

If there’s any variation in the schedule it’s an increased time spent migrating and a reduced breeding period.  Despite these time challenges prothonotary warblers in the southern U.S. raise two broods.

Now they’re on the move.  Their southward migration normally peaks in Ohio from August 10th to 20th.  By mid-September they’ll be in Veracruz, Mexico.  Who knows how much farther these two will have to travel to get home.

(photo by Kim Steininger)

If watching birds is called birding, what do you call watching flickers?

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(photo by Cris Hamilton of a very splendid male northern flicker)

The chimney swift flocks have grown again after weeks of reduced numbers. Since the swifts arrived last spring I’ve seen the character of their flocks change four times. 

First, the flocks were made up of spring migrants who chittered and ate on the way to their final destination.

The second phase was courtship in which trios flew synchronously, chittered loudly and completely followed each others’ moves.  Eventually those trios became pairs as the females chose mates.

During the nesting phase the flock was cut in half because one adult of each pair was always in the chimney incubating, brooding or tending the young.  The smaller flock wasn’t nearly as noisy.  No need to shout, the courting is over.

And now the babies are fledging and the flock is double or triple in size and noise. 

It’s fun to watch the fledglings learn to eat on the wing.  They still expect their parents to feed them so they follow them closely and beg a lot but their parents don’t stop.  The adults lead them through clouds of insects and the babies, whose mouths are probably open to beg, are stunned to find insects pop into their mouths.  All they have to do is swallow.

Soon they are swerving and chasing insects on their own.  It won’t be long before they’re as skilled as their parents and become indistinguishable as members of the flock.

(photo by Chuck Tague of a rescued chimney swift just before it fledged)

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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