Our nature writer tracked the birth of seven wrens

Two baby house wrens peer from their nest box/Jim McCormac

Our nature writer tracked the birth of seven wrens

Columbus Dispatch
July 2, 2023

NATURE
Jim McCormac

Early this spring, I hung a small bird box from a pergola rafter ten feet from my kitchen window. I had high hopes that either Carolina chickadees or house wrens (both are cavity-nesters) would appropriate it. Both species are common here, the chickadees year-round and the wrens from mid-April into early October.

Right on cue, a male house wren appeared in the yard around April 20, loudly announcing himself via his rollicking, trilled song. He wasted no time investigating potential nest sites, and my new bird house was one of them.

Males typically precede females by a few days, and almost immediately begin constructing dummy nests. They stuff twigs and other material into cavities that they deem suitable nest sites. When a female appears within his turf, and they bond, she examines the male’s potential home sites and selects one.

At this point, Mrs. Wren takes over the homemaking. He is banished from the premises while she rearranges or discards his contributions, and busily adds new material.

Fortunately for me and my curiosity, she selected the bird box and I had a ringside seat to the whole nesting process. In a few days, she had whipped the nest into shape. This involved the collection of hundreds of twigs and sticks, and grasses, hair and feathers for the soft inner cup.

The typical house wren clutch ranges from four to eight eggs, and the female lays one a day. This took another week. After that, the female settled into incubation duties. The male hovered around the vicinity, often gushing enthusiastic with song, but of little help in this phase other than attacking and driving off squirrels that roamed too near the box.

After almost two weeks, it became clear that the chicks had hatched. Both parents began carting all manner of insects to the nest: lots of spiders, beetles, moths, caterpillars, flies and about anything else they could catch. I’d estimate that over 8,000 meals were delivered to the nestlings.

At first, a wren with food would disappear into the cavity. As the chicks grew and got nearer to the entrance, eventually the parents had only to stick their head inside to deliver meals. An adult’s arrival sparked a cacophony of raspy squeaks from the brood. And what goes in must come out. The adults occasionally emerged with fecal sacs – neat little bundles of baby wren effluvia. These would be flown to distant shrubs or trees and discarded.

At 6:40 am on the morning of June 24, I saw a baby wren stick its head out the hole for the first time. I knew this would be the morning of departure. The parents’ behavior changed markedly, too. The female called continually and stridently, and the male commenced regular bouts of singing, to entice them from the box. After much wide-eyed wonder at the huge new world outside its box, baby #1 launched itself at 6:55. Its flight was surprisingly strong and took it 30 feet to a redbud.

Eleven minutes later, #2 departed to another shrub. The two wrens in the accompanying photo were #3 and #4, and they left at 7:14 and 7:16 a.m. Baby #5 didn’t tarry, emerging three minutes later. Then, nothing. I began to think everyone was out, but 25 minutes later, another baby peeked out. The shrinking violet gawked out the hole for a while, then flew the coop at 7:51 a.m. And yet one more lingered, but it didn’t want to be left alone and shot out the hole a minute later.

Seven wrens! All of them disappeared into the wilds of my backyard, and I wish them the best of luck. They will need it. After feeding locally – and dodging predators – the wrenlets will undertake a lengthy and perilous southward migration that could take them all the way to Mexico.

They’ll make this journey independently, relying on an amazing built-in GPS. If all goes well in the wintering grounds, they’ll fly northward next spring and most likely return to this general area. The parents that spawned them, or one of the offspring, will probably return to my Worthington yard to produce more wrens. And the world can use more house wrens.

Naturalist Jim McCormac writes a column for The Dispatch on the first, third and fifth Sundays of the month. He also writes about nature at www.jimmccormac.blogspot.com.

House Wren production in the yard

 

A House Wren peeks from its nest box. Their abode hangs ten feet from my kitchen window. 

When I placed this box early this spring, I had high hopes that the local wrens would select it. As always, the male returned in mid-April about a week ahead of the female, and busily began ferreting out potential nest cavities. He quickly became - to my eye - especially interested in this box.

Male House Wrens create several dummy nests - aggregations of twigs and other material in potentially suitable cavities. When the female arrives, she sets about investigating these dummy nests, while the male, presumably nervously, looks on. If she likes one, she selects it and then takes over finishing the construction.

Before long, it was clear that the nest box was her choice and she busily set about completing the nest. All manner of vegetable matter was brought in, and once all is done and the wrens are gone, I look forward to seeing inside the box. Apparently, it should be a fairly massive cave-like structure with a den cavity towards the back. The final stages of nest construction are done by the female, as is incubation of the eggs.

After a few weeks of relative calm as the female wren incubated the eggs, the nestling hatched. The onset of this stage was obvious, as both birds began busily harvesting all manner of food items and bringing them in. This one has a spider. Arachnids are a common prey item.

This wren brings the chicks a de-legged daddy longlegs. Other items include moths, caterpillars, beetles, earwigs, and various small insects that I cannot identify. When the pair is on a roll, they're returning with perhaps two meals every five minutes. This continues to this day, but the chicks will soon leave the nest.

What goes in must come out and a wren departs the nest with a fecal sac. They are fastidious about removing these to far-flung places, often apparently sticking them to a branch high in a tree.

It's been about two weeks since the eggs hatched. While I still have not seen any chicks at the nest box entrance, they have clearly moved nearer to the hole. While the adults used to disappear into the box with food, now they just poke their heads inside - the chicks are that close to the entrance. This means that VERY soon they'll make their inaugural flight from the box, and I hope that I am here to see it. If I had to bet, it'll be tomorrow, or at the latest, Thursday.