The Rest of the Wren Story

In June of 2015, I noticed that one of the yard’s House Wrens had begun feeding a family of Northern Cardinal nestlings. (Read my initial blog post here.)

Nestling May 30

The adult cardinals, especially the male, were also feeding the nestlings.

Nestling May 31

In that early blog post I wrote, “I wonder if this kind of behavior is common. Have the yard’s birds been feeding each other all along?”

Cardinal May 11

In searching for answers to my question, I ran across the Tough Little Birds blog, run by biologist Katie LaBarbera. I contacted her through the blog, and she replied that the behavior was unusual enough to be of interest to other biologists. Before too long we had a short article ready to submit for publication. After peer review and a few revisions, the article was accepted by The Wilson Journal of Ornithology and can be found in the current (September 2016) issue: House Wren (Troglodytes aedon) provisions nestlings of Northern Cardinal (Cardinalis cardinalis).

And now, as Paul Harvey might have said, it’s time to post the rest of the story…

wren-june-4

Back in June of 2015, while I was searching for answers online, the wrens’ brood hatched. For a few days the male wren stayed busy feeding both nests, dividing his time somewhat unequally in favor of the young cardinals. But something changed as the cardinals neared fledging. The last time I saw the cardinal nestlings accept food from the wren was on June 5th, and the last time I saw him approach their nest was on June 6th. (They greeted his visits on the 6th with silence.) On June 7th, the young cardinals left their nest.

cardinal-june-7

The yard stayed in a turmoil on the 7th, loud with the cries of hungry cardinal fledglings and nervous cardinal parents. (The male cardinal was particularly aggressive with larger birds that day, much to the dismay of a hungry brown thrasher.)

cardinal-june-7

cardinal-june-7

The wren, formerly so devoted to the cardinal nestlings, never approached the cardinals after they fledged. Instead he spent the 7th, and the following days, feeding his own nestlings. The young wrens stayed in their nest box until June 16th and 17th, eating spiders and praying mantises and a variety of other insects brought by their parents.

wren-june-10

wren-june-10

wren-june-10

wren-june-11

wren-june-12

The nestlings grew bigger and bolder each day.

wren-june-13

wren-june-13

And their parents worked harder and harder to keep them fed.

wren-june-16

By June 16th they showed signs of leaving.

wren-june-16

wren-june-16

And on June 17th …

wren-june-17

They were out of the nest box, but they were still hungry!

wren-june-17

wren-june-17

wren-june-17

When they left the yard that evening, I felt bereft. As I always do when the yard’s children move on.

wren-june-17

I wished, as I always do, to follow the fledglings. Or at least to know their futures. Did any of them survive? Have they, perhaps, visited the yard again in the weeks and months since?

wren-june-17

Let me know if you see them.

The Nestlings

Wren May 4

A house wren began claiming the yard’s nest boxes in late April. He spent days on end carrying twigs, working on nests in each of the boxes.

Wren May 4

House Wren April 29

He clearly preferred one of the smaller boxes, and built his most elaborate nest in it. When females showed up to inspect the nests, he led them over and over again to his favorite, as if arguing its attributes.

House Wren April 29

The activity around the wren boxes was so entertaining that I almost missed a developing cardinal nest in the overhanging honeysuckle.

Cardinal May 11

Cardinal May 9

Cardinal May 11

The wren watched the cardinals’ progress with obvious interest, but didn’t seem to object.

Cardinal May 11

The cardinals quickly completed their nest, and soon there were eggs.

Cardinal May 19

May 19

Cardinal May 25

May 25

And then…

Nestling June 1

June 1

When the eggs hatched, the house wren’s interest in the honeysuckle nest increased alarmingly. (More than one source reports that house wrens sometimes destroy nearby nests, pecking holes in eggs and even killing nestlings.)

Nestling May 31

But a closer look revealed that the wren wasn’t planning to harm the nest.

Nestling May 30

He was feeding the brood.

Nestling June 1

And so were the cardinals.

Nestling May 31

I’m confused, but the cardinals, the wren, and the nestlings seem content.

Nestling June 1

Nestling May 31

The cardinals bring seeds, while the wren scours the yard for insects.

Wren May 30

And the nestlings greet either meal with enthusiasm.

Nestling May 31

I wonder if this kind of behavior is common. Have the yard’s birds been feeding each other all along?

Wrens May 3

I suppose “wonder” is the key word here, as it usually is in the yard.

Nestling June 1

The Empty Nest

The house wrens’ nestlings fledged this week. They fledged while I was busy doing other things, and I regret missing the moment of their departure. (For more about the house wrens, see herehere, and here.)

Wren August 4

During the last two months, our little family of birds have been a constant source of amusement and amazement. At first the male worked alone, a tiny bustle of feather and song. Then his mate arrived, bristling with scolds. Together they transformed the nest box into a vessel seemingly immune to the laws of physics. They stuffed it with so many twigs that it should have burst at the seams or collapsed into a singularity. Instead it rocked gently in the wind as eggs were laid, as the first male lost control of the box and his eggs were destroyed, and as he reclaimed the box and eggs were laid again.

Wren August 14

In early August, the eggs hatched.

Wren August 15

Wren August 14

As the nestlings’ voices grew more and more insistent, the wrens again defied physics. They expended so much energy, feeding their young, that both birds should have grown weak and thin.

Wren August 14

Wren August 14

Among the insects I recognized, there were caterpillars, moths, katydids, and crickets.

Wren August 23

Wren August 23

The yard should have run out of insects, but it didn’t.

Wren August 23

Wren August 24

I don’t know how many nestlings they were feeding. More than the box should have been able to hold, wedged in with all of those twigs.

Wrens August 22

Wrens August 22

Wrens August 22

Wrens August 22

Wrens August 22

Then, around mid-morning on August 26th, I found the box abandoned.

I want to believe that I’ve heard the fledglings, in the days since, begging from deep within the wax myrtle, or from the neighbors’ yards, or across the street. I want to believe I would recognize them if they returned to the yard, which seems unnaturally quiet now.

Perhaps they will return next year, all grown up and beyond recognition. Perhaps they will fill the yard, once more, with songs and scolds. Fill the nest box with twigs and eggs, and, in the process, fill me with more delight than I should be able to hold.

Fall Webworms

Pear Leaf Aug 2

Earlier this month I noticed a few silk-encased leaves on the pear tree. I suspected the webs were the work of Eastern Tent Caterpillars, because I had found a few of these caterpillars under the pear tree last summer.

Last summer’s caterpillars never caused a problem in the tree, but this year the tree sprouted more and more webs.

Pear Leaves August

This afternoon I typed “tent caterpillar” into my web browser and within a few clicks discovered I was on the wrong track. It’s the wrong time of year, and our webs are located at the ends of branches rather than near the trunk. So these are not Eastern Tent Caterpillars. Instead, I believe they are Fall Webworms.

Caterpillars August

(My caterpillar identification process is not very scientific, consisting mostly of browsing the internet and trying find something that looks like my photos. Please comment if you can correct or confirm my identification!)

Caterpillars August

The caterpillars are not doing much damage. There are only six or seven webs, confined to the lowest branches on one side of the tree. The affected leaves are being eaten, but they represent a very small proportion of the tree’s total leaf count.

Caterpillars August

Caterpillars August

Even though our tree is not suffering, several nearby trees are completely shrouded in webs. As I’m reluctant to test the health of our pear tree, I’ve trimmed its most heavily webbed branches and opened the remaining webs as recommended.

Caterpillars August

I don’t know if the House Wrens will eat these caterpillars, or if they’ll leave them for other birds. But if they do eat the Fall Webworms, my work should make feeding their hungry nestlings a little easier.

Wrens August 22

Wren Changes

The house wren spent weeks perfecting his nest. He added twigs until no more twigs would fit, then filled the spaces between twigs with bits of spider web and grass clippings. As he worked, he sang.

Wren June 19

Several female wrens visited during those weeks. They hopped around the yard, inspecting all of the nest boxes and gourds, scolding the male when he got too close. The male wren reacted to these visits with a barrage of high-pitched calls, fluttering from perch to perch as he tried to lead the females to “his” nest.

Finally, one of the females decided to stay. She finished the nest over a period of three or four days, spending longer and longer inside the nest box each day.

Then I woke one morning to a furious battle. A new wren had arrived, and all three birds were fighting. By mid-morning, the new wren had driven the nesting pair away and destroyed their eggs.

Egg July 20

Egg July 20

The new wren visited each of the gourds and nest boxes that day, adding twigs to all of them. More than once I saw him remove twigs from the old nest and carry them to one of his new nests. He seemed particularly fond of the gourds, which the other wren had largely ignored.

I suspect the first wren was a very young male. He put all of his efforts into one nest, while most sources indicate that male wrens typically build several nests at once. He also seemed thoroughly over-excited whenever a female appeared in the yard, smothering them with enthusiasm.

By comparison, the new wren is calm and sedate. His sings less, and his song is softer. He follows females, when they appear, but does not flutter and scold as they investigate his nests. This afternoon one of the females began adding material to the old nest, and he let her work in peace. He watched, singing occasionally, but stayed out of her way.

Wren July 30

I’m fascinated by the new wren’s behavior, which seems like a paradox to me. He arrived in a whirl of aggression, complete with egg destruction, but his activity since has been passive. What triggered his initial invasion? And will he be able to hold the nest he won?

Wren July 30